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Thread: Seating depth...and such

  1. #1
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    Smile Seating depth...and such

    A subject of depth...pun intended.

    I got a new rifle last week. Oh, not a new one, just somebody's old hand-me-down, and after a good clean up and examination, (It was really pretty clean) I set about to find the chamber dimensions and where the lands could be reached with several different bullets.

    I record the serial number of the rifle and the weight and type of one particular bullet on my data sheet. One bullet per sheet which has a place for five different loads. This is usually all with one powder, but may be different. I used my Stoney Point seating depth gauge and modified case for the caliber (in this case, 338 WM) and push this particular bullet (a Nosler 225 grain partition) all the way into the chamber until it contacts the lands and stops. I then lock down the tool, extract the bullet and measure the length. I usually do this with a few bullets from the same box to get a good reading.

    Then I record this dimension on the data sheet for this bullet under the title "Contact Length". This is the Cartridge Over All Length (COAL) with this bullet against the lands of this particular rifle. Then when I want to load and seat .020" off the lands I just seat it .020" shorter than the "Contact Length". I do these steps with all bullets of the caliber that I intend to use, or what is on my bench at the time. Each time I try a new bullet in this rifle, I measure again and start a new sheet. This keeps things straight and I don't loose my notes this way.

    I develop data with each particular rifle and each brand of bullets (even of the same weight) with this technique because different bullets have different noses. With this systematic approach I'm able to determine with actual shooting test which seating depth I used and which the rifle prefers. Which of course is the real purpose. This can certainly be done without the Stoney Point system but it is much easier with it.

    Now it must be noted that each individual bullet from the same box will have a slightly different nose length and this measurement will vary. The seating stem of the die however will contact the bullet much the same way the rifling does, below the nose at some point, so even though the COAL will vary by a few thousandths, the actual distance from the lands will be the same for each round loaded with the same die setting. There also is available an additional tool for the Stoney Point system to allow contact with the ogive of the bullet and may make this measurement easier for some. I have found that a few thousandths variation in length does not affect much of anything, accuracy or pressure, as long as you're not in full contact with the lands.

    I then load ten rounds of each powder charge weight of the selected powder. In this case it was the 225 partition and RL-15 powder with FED 210M primers. On this first data sheet I loaded five different loads in one grain increments. I used RL-15 since this was a carbine length barrel and I was looking for low Standard deviations (SD) as indications of consistant powder burn. Now if your good in math you may have determined that I have loaded fifty rounds. I think that was last Thursday nite. Shooting took place on Friday and Saturday between rain showers.

    These loads were fired and chronographed in two different rifles, five rounds each of each load, and each load of five was custom tailored to each rifle, at .020" off the lands. Rifle "A" the new carbine 19.3" barrel and rifle "B" an old proven 22.5" barreled rifle of the same make. There was a lot of cleaning in between the shooting. As it turned out, the carbine turned in high SD's and the longer rifle had low numbers so I think I'll try 215M (magnum primers) and do it all again. Maybe RL-15 needs more barrel or more spark, we'll see.

    All these loads were in new Winchester brass which was neck sized with Imperial dry neck lube (graphite) then trimmed to .010" shorter than max length and deburred. I do not cut primer pockets to uniform depth or uniform the flash holes in brass until it is fired once. That will be done for the next firing. This fired brass is then measured at the webb to determine case expansion, and this measurement is also recorded for each load for each gun on the respective data sheet. I also have a place to record factory ammo case expansion and velocity, etc. but rarely buy factory ammo. This brass is also kept seperated (in small zip lock bags) until all measurements are taken and new primers are seated. This helps to determine if a load was excessive, seating new primers with little or no resistance means the pocket is stretched, a sign of excess pressure.

    Now it seems I must do all this again this week end. This time just 25 rounds of the same charge schedule as before but with the hotter 215 primers. I don't know why I thought 210's would work. I won't test with the older rifle since I have that exact same data recorded already, with 215 and now 210 primers.

    I'm sure glad I don't play golf! This is what I do, load, shoot, load, shoot, load.... Thanks for watchin'.

    Murphy
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  2. #2

    Default Determining seating depth

    Murphy,

    For a couple of years now, I've been going through a very similar routine to determine, what you call, "contact length". I also generally reduce that maximum by .020" to get my cartridge OAL when I start working up loads.

    I'm not familair with the gadget you're using to determine contact length. I've been using a very inexpensive little set-up from Midway, called the Frankfort Arsenal Cartridge Overall Length Guage (regularly $14.79, commonly on sale for $11 to $12). Instead of the cleaning rod that FA recommends using, I use a wood dowel of appropriate size. Cheap, easy, don't know what I ever did without it. You can certainly learn a lot about bullet shapes and SAAMI OAL specs.

    Also: gotta be careful that the sweet load you work up fits the magazine. With some of those new fangled, long-for-caliber bullets, you can't run 'em through the magazine if they're only .020" shy of contact length.

    Regards.

  3. #3
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    Default Standard Deviation

    So, for those of us saving our nickels to get a chronograph, what do you consider to be "high standard deviations" in velocity?

    Is it a relative measure for any given rifle/powder/primer (e.g.: I get higher deviation with powder x than powder y), or is there a rule of thumb that tells you when you've got a good thing going (e.g.: This first powder/primer combo has standard deviations under x% - no sense experimenting further)?

  4. #4
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    Cool Standard SD...

    8X57,

    I'm glad you asked that. You see, I didn't just post that to impress anyone with my loading talents, just for information and to stimulate this new Handloading forum.

    A good question. Standard Deviation is a number which represents the predictability of the next shot. The next shot will be within the SD value of the mean (average velocity). So... the lower the better. Remember this is not the same as extreme spread.

    Now for any given caliber, a low SD will vary greatly. A 30-378 or a 7mm RUM may only muster a 25 for the lowest SD and a 6PPC rarely ever is over 4 fps.

    With what I suppose is considered standard hunting calibers, 30-06, 338 WM, etc. I want single digits, less than 10. I'll take anything in the teens if thats all I can get, but won't use a load that is greater than 20.

    Those cartridges that are called "overbore" or what I call low expansion ratio calibers, will be worse. Extreme spread and of course SD will be higher than any "standard" Caliber. This low expansion ratio means that the ration of bore volume compared to powder volume is low. Too much powder and no room to burn it. Powder burn is inconsistant when large volumes of powder are used and this brings wide variation in the exit velocity of each shot. It is difficult to ignite huge loads of powder, thus the need for the hotter spark of the magnum primer. Fed. 215 is generally considered the hottest spark.

    There is no confirmed correlation between low SD's and accuracy but it has shown to play a part, and the most accurate of calibers always have low SD's. A major concern for me is that with wide variations in velocity there is also wide variations in pressure. That isn't good when I'm trying to find the peak pressure and only one round of ten shows excessive pressure and nine donot.

    Certain types of powder will show higher SD's. Generally the slower burners will be higher. Of course they are also used in higher volume, which doesn't help. Also the ball types of propellant typically show wide velocity variations and SD numbers. This due in part to their being more difficult to ignite.

    I will cut to the chase here. I've been doing this for a long time. I have burned (in cartridge cases) a ton of powder. I use what has, for many years worked the best for me. I also use the new stuff in volume enough to determine if it is better, or worse than the old. I keep good notes. I've been using a chronograph since the 70's when I made my first one. I am an engineer, a scientist, I document my work. For a number of years, Norma powder was way ahead of everything else. The RL-series of powders are made in the same plant and parallel the Norma powders. The newest Hodgdon extreme powders are the best I've ever used. Absolutely nothing will compare with them in what I have termed "standard calibers". The overbore, Ultras and Wby calibers on the 378 case (30-378, 338-378) don't really have a good enough, slow enough powder available to give the results I seek. RL-25 is too fast for some of these yet is still the best to be had for consistant velocity. I think to be fair, the big cases must be judged with a different standard.

    A chronograph is a tool and, as for me, I have used it extensively. It will tell me I'm approaching peak pressure before the brass ever will. One of the bits of data I collect is the amount of change in velocity (delta V) per unit (grain) of powder. If I load 5 different loads with the same powder type, same case, same primer and same bullet, (this is the way I do it) then charge each of five (or ten) cases with 56.0 grains, then the next five 57.0 grains then the next 58.0...etc. Then when cronographing them I see; (This is from one of my chronograph tapes.)

    56.0 grains velocity=2680 fps, SD=17
    57.0 grains velocity=2722 fps, SD=11
    58.0 grains velocity=2758 fps, SD=08
    59.0 grains velocity=2783 fps, SD=16
    60.0 grains velocity=2797 fps, SD=21
    (This is the mean velocity for 5 shots)

    56-57 grains velocity gain=42 fps
    57-58 grains velocity gain=36 fps
    58-59 grains velocity gain=25 fps
    59-60 grains velocity gain=14 fps.

    While I'm gaining about 40 fps per grain I'm good. As the velocity gain drops off the pressure is still going up, this is called the knee of the curve (plotting delta V). This occured, with this load, at 58-59 grains. The last good load was 58.0 grains, it had a 36 fps gain and an SD of 08. The thermo-dynamics of this combo are happy. Now lets see if the barrel is happy, shoot for group. It almost always is better accuracy than any "unhappy load". I will likely go back and load 56.5, 57.5, 58.5 and try these in the same way. Maybe the 57.5 or the 58.5 load will be better, we'll see. And, often I will try 55.0 and 55.5 to verify my trend. Now it's time to try another powder with this same case/bullet/primer combo. It never ends!

    Just another blather on loading. Brought to you for your enjoyment by this friendly neighborhood Handloading Forum.

    Good shootin'.

    Murphy
    Last edited by Murphy; 09-07-2006 at 12:48.
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  5. #5

    Default

    Hello Murphy,

    I hope you don't take this the wrong way, but I read this thread twice, and still can't figure out the purpose of your "testing". Maybe you are a professional consultant to some SAAMI affiliate?

    Anyway, what I took from your posts was that you are researching standard deviation of the velocity of an exact powder charge in two rifles of the same caliber, but with different barrel lengths.

    This could lead to a pretty interesting discussion. I don't really see your purpose or goal for the data gathering. Are you a PE or Ballistician type tech guy doing paid research? I'm fairly new around here, so I don't know.

    What has crossed my mind relative to your discussion here are these points:
    -Does velocity deviation of a powder charge really matter?
    -Is the data "valid" without barrel consistency?
    -Does in-depth or extensive "testing" for sweet-spot loads with magnum cartridges burning 60+ grains of powder do anything more than lead to barrel errosion?

    I submit, with respect, that consistent velocity of a given powder charge is secondary to the accuracy of the load and bullet. Additionally, unless the barrels are Pefectly Identical which is almost an impossiblity unless they were taken from one piece of steel that was rifled and then cut into two blanks, the results will have to be suspect. Further, unless the conditions including temp and humidity are identical, the info is suspect. There are just so many variables to control that, aside from curiosity, I can't see validity to the data.

    Benchrest shooters predominantly esteem small case, mild cartridges like the .22 and 6mm PPC and BR. Even so, competitive benchresters will retire a barrel once it has had about 700 rounds fired through it. Maybe the barrel is still "okay". Compared to a H&H magnum based ctg or larger 404 Jeffrey based chambered barrel those benchrest guys are seeing no erosion or damage. Yet, to get the best results they do discard barrels before they show diminished accuracy. Accuracy is what they are all about.

    It is now almost commonplace for rifle handloading afficionados to talk and write articles about their Herculean and holy grail efforts to get "the right load" for their gun. Is there such a thing?

    You wrote about testing 3 powders loading 10 rounds in one-tenth grain increments and firing half in one gun, half in the other. Then you were going to repeat the test with magnum primers. Are we really talking about shooting 300 rounds of .338's through each rifle, just to find a low standard deviation powder charge?

    It seems to me that each bullet down the tube actually changes the barrel dynamic to a very small degree. As each bullet deposits more copper or moly on the lands and grooves it narrows the diameter of the barrel and increases pressure potential, but also might reduce the friction subsequent bullets encounter. Anyway you look at it, each shot produces a new set of variables.

    I was out laying in the local gravel pit, sighting in my rechambered .338-300 at 100 paces a few days back. I got the scope on track and fired my 5 upper limit loads. I reasoned, "I am going to load heavy for woods use in my area so let's start there". I was fighting a very heavy trigger, and laying in the gravel using a bipod with only 5 rounds, but 4 of the 5 were touching each other with the other close by. I was usinga round aiming dot. Square would have been better. An 7" bipod is not on par with a concrete slab bench top and Protektor bags, but it sufficed.

    I figured to try 1 grain spread increments. I never fired the other ctgs. After adjusting my trigger, I need to confirm my zero; but I figure with 4 of 5 rounds touching, I am close enough. With a more reasonable trigger pull, things ought to improve.

    How many heavy charges of XMR4350 can I put through my rifle before I see errosion and damage? I don't know. I do know that getting "lucky" with the first 5 tested means I will get that much more service out of the rifle before I have to rebarrel. I would bet that many guys do more damage to their barrels trying to find the "sweet spot". About the time they find it, it is time to rebarrel.

    Most guys are looking for a "magic load". They have never experienced using superb scope mounting systems like Badger Ordnance or 30mm tubed scopes. Guys will buy a super custom gun with a $500 barrel and then mount their scope in an STD type system. No wonder they are looking for the holy grail, their scope mount is junk!

    Benchresters are all sorts of things regarding their handloading techniques. Yet some report that powder variations of .1 grain have little effect on accuracy. Some are so obsessive-compulsive they will split a grain of spherical powder to get the scale "just right".

    Each to his own. Most of shooting is between the ears anyway. If you have confidence in your gear, you make your shot; whether once in the field or 50X a day from the line.

  6. #6
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    Default Experiment or Experience?

    Lester,

    No. I don't take offense to your post, if that's what you meant. It's very informative and brings up somevery good points.

    Since you organized your points so well I can take this, a paragraph at a time and answer/explain what it was about.

    I have been a paid ballistics consultant, but that is my purpose for all this.

    Someone had asked for a definition of SD, so I went there. I have recently obtained a new 19.3" bbl carbine in 338 Mag. Several times on this forum I have been asked how much velocity loss would there be if I cut the barrel of my XYZ rifle to 18" or 20" or 21",etc. Or shoud I buy a certain short barreled rifle. There is no way in hell to know the velocity or even make a good guess about it unless you actually chronograph several such candidates.

    Unlike some people I don't just repeat what I read in a magazine, I actually do it and then speak/write about. (Experience)

    I had intended to post data of both rifles shot side by side with exact loads for comparasion only, but that went south. As you have said no two rifles are ever alike even exact duplicate rifles, and that is certainly true.

    A funny and irritating thing happened a while back. I had obtained a rifle to send to a smith to have rebarreled. It was a 28" barrel on a Mauser action of very good quality and an HS Precision stock. Why 28" I don't know, but it was . I fired 400 rounds through that rifle and every one through my Chronograph. I cut and crowned the barrel an inch at a time back to 18". This was an all winter project. Without going into the details of the "test" lets just say, I had a pretty good idea about velocity for that caliber and loss per inch, for that caliber after I was done. Some one on this forum asked how much velocity loss for ABC caliber if I cut to XX". I mentioned my experiment and some one else said xx fps per inch from a guess or parroting a magazine writer an that became the "standard" that was repeated by everyone else who posted. It was in total contradiction to my experiment.

    The purpose of my "work" is research for a book. Have you ever opened a loading manual for you favorite caliber and found you exact brand of rifle with your exact barrel length? Not there is it? I use hunting rifles with standard barrel lengths.

    Your questions.

    Velocity deviation does matter. You may get a load that is accurate with wide SD but the same load in the same rifle will be better when the SD is lower. Always has been in over 400 rifles and geez..guess how many rounds.

    Is data valid without barrel consistancy? I'm not sure of you question. Is it that your belief that the barrel changes after each shot so much as to make each shot a new load? The barrel doesn't change in one shot or a few or even a hundred, after it is "broken in". Some folks who only shoot a few rounds a year through a rifle couldn't possibly kown that a few hundred rounds won't matter at all in a modern rifle. I finally sold after ten years a rifle M38 Husky in 6.5x55. It had over 3500 rounds through it. It had been scoped before I bought it or I would never have tapped it, but it would shoot half inch groups when I got it and it shot 1/2" groups when I sold it for $250. It was made in the early 1940's and it was used when I got it. I have fired more 6.5x55 Swede ammo than all the folks at Sierra, Speer, Nosler, and Hornady put together. Nobody cares.

    Certainly something could be said for a barrel accumulating fouling and change it's dynamics but we have good cleaning supplies. A good barrel will hold it's sheen for a number of shots.

    Does shooting lead to barrel errosion? Yes. But A rifle that is shot and cleaned and cared for properly will last for over 5000 rounds and more. I fired my last "clean" 600 yard target, before I quit Hi-Power, from a rifle that I had put just short of 4000 rounds through. The group was a mere 9" but as I recall I came in 19th place in that match. Yes my short line was good too.

    This nine inch group is very good for any shooter, prone, with aperture sights, no by-pod, no sand bags, no windflags, no kids around, just me and my rifle. Springfield M1A, Gale McMillan barrel. (Gale McMillan is the guy who says barrel break in is just wearing out the barrel.)

    Barrel wear extoiled in magazines and on the webb is as ancient as black powder and corrosive primers. Few people understand it today. It's true we used to rebarrel the match rifles every year after only about 1800 rounds, but that was an opportunity window because the next interval would be 3600 rounds after the next shooting season. Now I don't think that was necessary. I had a rifle for sale here on this forum, an individual agreed to take it then backed out because, I think, some one here said it had been shot out. Mule muffins!

    ...consistent velocity of a given powder charge is secondary to the accuracy of the load and bullet. You mean the accuracy and the bullet is more important? Yes, a bullet is the most important part, it does the work, be it target or beast, it is my contention that velocity and velocity variations are paramount to good accuracy in the first place. It all boils down to the barrel and the bullet.

    There is usually only one velocity/pressure for a particular bullet to go down a particular barrel and exit undisturbed. I say usually because, within the capability of the rifle for that caliber, the two or three other velocities are beyond reach in that barrel due to pressure limitations. A typical hummer velocity might be 2740 fps and the next harmonically ballanced velocity might be 3211 fps. It's hard to get that second velocity from a 24" barrel in a 308 Win.

    Is there such a thing as the right load? No, so why don't you shoot a different powder and bullet in your 338-300? Of course there is. Is there another way to find it? Yes you can even stumble over it in the dark. I don't do this against all internal belief. I do this because I'm a technical mind and I like the complexities of it and I like guns and I like to shoot. Most people who own guns that visit this forum are just looking for a "hunting rifle and one hunting load" They are not experimenters and even if handloaders they just want to find the one most accurate load for their rifle, sight it in and forget it. They don't have the time, money or inclination to persue the answer to the depth that I do and yet, I enjoy it. So, I think that I have information and useful data for some of them. Apparently I am wrong.
    The more I interact with this forum the more I think a book of this type would not sell at all.

    I resist any comparison of myself to benchrest shooters. The only thing we agree on is powder volume not powder weight is the key. Fill this case to the same point everytime. (BR shooters don't weigh their powder, they weigh their cases.)

    Also I used one grain increments not 1/10th grain increments, as is the norm for hunting rifle cases.

    I think I can see how you and others see no reason to do this, also they don't want to buy a handloading manual to find a starting point, but they ask questions of total strangers about such important subjects as how much powder and what powder do I use in this case. How did you arrive at the load for your 338-300? Did it come to you in a vision? Was it just a guess?

    You mentioned guys looking for the magic load and using inferior equipment. I think from what I've seen at the local range, they have no ability to shoot a 1" group with even the finest of equipment and ammunition. Furthermore, field shooting ability is far more important than an accurate rifle or a good load when in the hunting fields. This all goes back to the mindset and confidence in ones equipment. If you believe it's good you will shoot it well. The human element is an undeniable aspect of success.

    This has been very good to go back over this and reevaluate, thanks very much for your input. No offense taken or intended. I appreciate your input.

    I'm going out to shoot.

    Murphy
    Last edited by Murphy; 09-11-2006 at 13:55.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



  7. #7

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    Thanks for your reply.

    I understand that 7.62x51 cartridges and other hi-power ctgs will not erode a barrel as promptly as will a magnum ctg. The difference is maybe 75 grains of powder in the magnum versus 45 or 50 in the 30 cal hi-power ctg. Additionally, errosion will be a function of barrel bore diameter. 75 grains in a 458 Winchester is not going to errode the way a max dose of powder will in a .264 Win Mag.

    I have about 10 manuals going back to the first one I bought in `76.
    The bullet companies will not supply starting data for cartridges not in their books; standard, wildcat or foreign.

    Since you asked, I corresponded with another guy who does some wildcatting and outlined my proposal; that data for a wildcat can be interpolated, and got some confirmation that the larger diameter bullet can take more powder if cases and bullet weights are the same. I was told I was on the right track. After reaming my .338 Win Mag chamber to .338-300, I test fired my median load (65 gr xmr4350) in the .338-300 case. It was very mild.

    I noted that the .300 Win Mag necked up to .338 is about the same as the .300 Wby mag to .340. The only difference is the neck diameter all other dimensions are constant. So I found the bullet weights I had and the powders I had and noted the extra powder in the .340 ranged from 16% for 250 gr bullet to 12% for 200 grn. I did not have IMR 4831 and there was no data for 250 gr bullets with xmr4350. So I extrapolated and felt safe with 76 grains as a upper limit, test fired the ctg using a hornady bullet and got no pressure signs. Firing these at my gravelpit range, they grouped well, showed no pressure signs, and the load is under the max percentage I identified.

    You are right about velocity variation. Everything we try to do if we produce accurate ammunition is geared toward elimination of variables.

    The benchrest guys (I'm not one) order two barrels if they are working into a new cartridge. One for load testing and the other for match use. They HOPE the same barrel from the same maker will place their bullet in the same or better grouping than the barrel they wore out finding The Load.

    Shooting is not my life. I have a .308 varmint special that I built from a used remington PSS barrel, an old Rem 700 SA action, and a PSS stock from Brownells. Shooting off a bunny bag with a sock full of sand at Dietz gun range, after I changed from Leupold mark4 rings to Badger Ordnance rings, I shot 8 to 10 5 shot groups under .42" as measured with a Mitutoyo dial caliper. best group was .334 on a hot windy day. I fired about 4 five shot groups under .75 that day at 200 yards. The bullet diameter was Not subtracted from the group sizes I'm reporting, as is common practice for benchresters, btw.

    I loaded 45 grains of IMR 4064 with a Federal match primer and a 168 Sierra MatchKing using a RCBS competition die set. The brass was Win or R-P, it was not my Lapua brass.

    So, maybe I got lucky? Finding out about Badger bases and rings was the main trick. Having a Leupold Mark4 6x scope with a target dot reticle can't hurt, but I found if I could hold the exact same spot, time after time, and get that "just right" trigger break, the bullet goes to almost the same spot. Maybe if I tried a 24x competition scope I could do even better at 200 yards?

    I have a Badger mount and rings on my .338-300. I think most of the accuracy I get stems from the rifle and not the cartridge. I think the barrel is not as critical at close distances under 300 yards as is the scope and mount system.

    I really believe more damage is done by shooting hundreds of loads looking for The Load, at least in Magnum rifles. I've read Gale McMillan's (may he RIP) comments on break in, and Daniel Lilja's articles about his barrels. I have also read comments that .300 Win Mags are usually about shot-out somewhere around 1000 rounds. Maybe that's only apparent to LongRange and Competitive shooters?

    I haven't shot my hodgepodge PSS since coming to Alaska. Too far to a real range and too many other "important" things to do when we go to town. It is fun to spend the afternoon at the range, taking time for the barrel to cool down, cleaning rituals every 5 or 10 firings, waiting for the wind to abate or be where it was when the last shot was taken.

    I think the proof of the pudding is in getting all 5 or 10 shots in the same hole. That is where The Load might make a difference. Then again, how many guys do all their practicing at the bench, and then can't hold well enough using a sling to put 5 shots in a 3" circle at 100 yds? 5 shots in 3moa is just fine for moose hunting, isn't it? So why burn up that magnum barrel at all? Better to burn ammo in practice using the sling and taking standing shots.

    What kind of groups are you getting from those loads?

    Thanks for your time in considering these rambling thoughts.

  8. #8
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    Default Velocity and SD...

    Lester,

    Sure, the more powder that is burned and as well the pressure and temperature of the burn determines the rate of erosion. But I think it greatly over exaggerated. Expansion ration is perhaps the greater factor, (Large volume cases with small caliber bullets.) since about everything now is about the same pressure and temperature. Some powders make this worse and others make it better.

    I found an article on the home page of 24 hr campfire about accuracy and I'll leave with a quote from that. My routine has pretty well been like this for about twenty years.

    Quote:from 24hour campfire article by John Haviland.

    Jeremy Millard, an engineer at Hornady, is a thousand-yard bench-rest shooter. Millard said that developing an accurate long-range load for a rifle requires lots of experimenting. "A load that shoots accurately at a hundred yards might not even be on the paper at a thousand yards," he said, "so you have to try different things to get your rifle to shoot its best."

    When Millard is looking for that just-right load, he tests two or three powders with Hornady bullets in ten-shot strings. Ideally, he is looking for extreme spreads in velocity of twenty feet per second or less and standard deviations in the single digits. "If I can get velocity spreads down fairly low, that's one less accuracy variable I have to worry about," he said.

    A load that shoots bullets at constant velocities should shoot accurately from a properly tuned rifle. "You may have to tweak the powder charge to bring the velocity up or down maybe a hundred feet per second to tune the load to match the barrel's harmonics," Millard said. "Finding that sweet spot can really tighten your groups."

    When Millard is looking for that just-right load, he tests two or three powders with Hornady bullets in ten-shot strings. Ideally, he is looking for extreme spreads in velocity of twenty feet per second or less and standard deviations in the single digits. "If I can get velocity spreads down fairly low, that's one less accuracy variable I have to worry about," he said.
    A load that shoots bullets at constant velocities should shoot accurately from a properly tuned rifle. "You may have to tweak the powder charge to bring the velocity up or down maybe a hundred feet per second to tune the load to match the barrel's harmonics," Millard said. "Finding that sweet spot can really tighten your groups.
    Last edited by Murphy; 10-05-2006 at 18:29.
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  9. #9

    Default

    Hi Murphy,

    Sierra Bullets likely still has the Competition section in their manual. They make The Best mass-produced target bullets. Doubtful that the guy at Hornady is shooting Sierras. That section is a great place to start looking for longrange or competitive loads. Their bullets are worth starting with too.

    I recall an article in Precision Shooting about 7 years back, when I bought it regularly, how an 86 year old guy from Wa/Or won the big Pa 1,000 yard shoot with a 10 shot group under 3.7 inches. Of course, he was shooting some kind of unlimited class rifle; a barreled action in a "stock" that weighs 30 lbs or more. He was shooting a 300 Winchester or 30/378, I think.

    I would like to have a chronograph; but not too much since I never acquired one. The recording chronys with printer or computer interface are, I'm sure very versatile.

    About 20 years ago I found a copy of Warren Page's The Accurate Rifle at a resale shop for .50 cents. Page was always fun to read in Field and Stream. When I got interested in accurizing my Varmint Special I found the book even more interesting. There are a couple more recent books that discuss accurate rifles, precision reloading, and technique. Sinclair Intl has a good in-house publication on the subject too. Boyd Mace wrote a book about Varmint Shooting and Glen ? wrote the current overview book on benchrest shooting, much like Pages book.

    I was reading comments by barrelmaker Boots Obermeyer last night. He is/was a pretty competitive shooter and knows his stuff. He was talking about the myriad factors that contribute to accuracy, and commented about the newer powders used in High-Power guns that deliver more velocity burning the barrels out sooner than they used to see.

    Interestingly, another comment I saw mentioned that Moly coated bullets cause extreme oxidation regardless of cleaning methods in under 200 rounds fired. Evidently the corrosion occurs UNDER the moly, and the coating bonds to the steel when fired.


    I would say that the successful 1000 yd shooter would be better off knowing how to dope the wind and to have a scope with reliable movements and repeats if he could choose where to have his strong suit. We are talking about 17 to 20 lb rifles in the lightest class (I expect), 30 inch barrels, heavy Stolle actions, heavy rings, massive scopes. Sure, having uniform powder results has to help, but is the variation critical?

    Obermeyer discussed Varget in particular as not being the "end all" powder.

    How much effect do primers, brass, bullet base and uniformity of barrel diameter have on your results? If we could find 2 identical brass cartridges, and count each spherical granule of powder and be sure of perfectly identical primer ignition, we could isolate factors and investigate.

    Unless you are using Lapua brass, which is The Best There Is, you run variation risk. Maybe you sort by weight and water capacity, but maybe the wall thickness is not constant?

    Ultimately, are we concerned with proving a rifle accurate or tweaking its ammunition to the Nth degree? What is "accurate enough"? Jeff Cooper addressed this very topic in Mel Tappans Survival Letter in 1977.

    Maybe that benchrester needs extra barrels from the same rifling machine operators run of the same day and hour, so he can burn out a barrel or two searching for the extra .005 that gets him into the finals. But, what about a rifle that's carried afield?

    What difference does it make if a guy has the finest ammunition, but doesn't know how to use a shooting sling and never practices offhand techniques. Do local ranges allow standing, sitting and prone position shooting for the general public? Most likely not because of liability insurance and accident risk.

    Cooper said a guy that can place 3 shots in one inch at 100 yds in less than 5 seconds was a real Rifleman. Trigger control, steady hold, and reflexive action when sights align is easy to theorize, very hard to do. Like piano playing is just striking the right key at the right time.

    Obermeyer commented that Barnes X bullets were very good because they had thick and uniform bullet jackets. Most custom makers (back then) used Sierra or J4 bullet jackets.

    Theoretically, I know that a -0- deviation in velocity is likely better. But how much better? Is constant velocity as critical as the other elements that combine to correctly place the shot?

    Maybe if you were testing from a test platform, unlimited class barreled receiver in a 40 pound mounting platform, using air-gauged barrels uniform to .0003 over the whole length; you would isolate your variables "better"? I don't know.

    Can a 1000 yard accuracy load be "inaccurate" at shorter ranges? I don't know.

    If you were testing for bullet placement accuracy at moderate range, I guess you could spend $5 or $7K for a Chandler or Accuracy Intl rifle and be sure you had all the variables of the rifle covered, but I bet they would caution on expected barrel life, at least for .300 magnum and for sure for .338 Lapua. As Obermeyer said, more velocity, more powder; barrels wear out faster.

  10. #10

    Default Muzzle velocity & verticle spread

    An additional important reason to minimize velocity spread and SD (standard deviation) in long range shooting is to minimize the verticle spread caused by the differing muzzle velocities. Not so important out to 3-400 yards, but significant at 600 yards on out for either hunting or benchrest shooting. How could one ever expect to shoot small groups at 1000 yards with high SD and high extreme muzzle velocity spread loads? I don't shoot competitively, but I will take some long shots while hunting and I also consider it important to minimize SD and muzzle velocity spread to help avoid high/low hits at long range. There's no way around this issue other than a chronograph, reloading, shooting, more reloading, and more shooting until you find a good load configuration. My two cents...

  11. #11

    Default Murphy's info

    I have been pulling triggers for 50 years. Loading my own ammo for 32 years. I have 2 of Bob Hagles old books and love them. I also know talent when I see it and I know when someone is dedicated to something. I have been reading this forum for about a year and my 2 married daughters now read it. So Mr. Murphy I am going to buy your book. I look forward to reading it. Hurry up ! Life is short. You can always write another one. I want it signed also and try to keep it under 150.00 bucks so my wife does not think I am nuts. Thanks for sharing the great info ! By the way, do you know a guy named Chuck Taylor ?
    Last edited by Murphy; 10-05-2006 at 23:06.

  12. #12
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    Default I'll Hurry..

    338 Mag,

    Thanks for the kind words. I'm working diligently, ok, maybe not but I am working on it.

    Chuck is the man!! An incredible human and shotists! I am not in his league. He is major all the way. I've attended his course, I think I came in 29th in a class of 30. We are of the same era and duty but he's a super hero, over achiever type. A pretty impressive guy for an Army puke.


    I am a shooter. I enjoy guns and shooting. Everyday of my life, in my thoughts, in my plans, in my very existance, are guns and shooting. I am dedicated to the craft, to the art of the gun.

    Americans have made this country great. Americans from all walks of life, from all cultures, from all countries. It is from their toils we have risen. We have a heritage steeped in the skills, the fortitude and the perseverence of our ancestry. An integral part of that are the tools used to build this nation. One cannot look into this turbulent past and consider the gun inconsequential. The gun is and will be a significant and necessary part of those endeavors through which a people build a nation, second only to the very spirit of those in the midst.


    I appreciate your comments. Thank you very much.

    P.S.
    I didn't really edit your post just accidently hit the wrong button.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



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