Results 1 to 16 of 16

Thread: question for Murphy or other knowlegable reloaders

  1. #1
    Member
    Join Date
    Apr 2006
    Location
    Wasilla
    Posts
    108

    Default question for Murphy or other knowlegable reloaders

    Was sizing some brass for my 300 weatherby tonight and started looking for load data to work up a load for it. I checked both the Nosler and Hornady manuals. One listed a load for IMR 7828 as starting at 80.5 gr with 84.5 being max the other listed 81.9 as the max load. This same thing was happening for more than one powder that I looked at. What gives????? Which data do you believe???? This data was for 180 grain bullets.
    Last edited by grousehunter; 07-17-2009 at 18:59. Reason: Additional info

  2. #2
    Member marshall's Avatar
    Join Date
    Nov 2007
    Location
    Near Phoenix, AZ
    Posts
    1,814

    Default

    Different bullet manufacturers have different bearing surfaces and jacket material. Those differences alone can cause different pressures and therefor different max loads.

    Charges are not just generic for a bullet weight. Sometimes a close look at the published data will reveal that the manufacturers are using different length barrels in their testing. Different cases and or primers will cause different data too.

    Always pay close attention to the descriptions and compare data then choose a load that is less than max for your testing to begin.

    Professor Murphy can shed more light on this subject when he shows up.

    Cheers

  3. #3
    Moderator
    Join Date
    Jan 2005
    Location
    Midwest
    Posts
    4,431

    Default

    Ditto, Marshall. I would only add that each company uses a different rifle with a different chamber, etc. as well as different powder lots. Also different pressure reading equipment may account for the difference. I don't believe any of the loads listed will destroy a rifle but may give a tight bolt lift and shorten brass life. You need to be 5% below max to start and go up one grain at a time. If you have a chronograph and a 26" barrel, stop at 3250 fps, that is likely safe.

    I have loaded the 300 WBy with 82.0 grains of IMR 7828 as a standard load in several rifles but that was with only one lot of IMR 7828 in one 8# jug. Your mileage may vary.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



  4. #4
    Member
    Join Date
    Apr 2006
    Location
    SwampView AK, Overlooking Mt. Mckinley and Points Beyond.
    Posts
    8,810

    Default Speculation...............................

    I would tend to use the data from the maker of the Bullet I intend to use. Hornady for Hornady and Nosler for Nosler.

    I figger bullets are different, not only as to bearing surfaces, but also hardness. Some don't have as much give as those of other brands.

    Older Nosler Data, that derived long ago, MAY have been when using the OLD Nosler (Partitions) bullets that were machined, so they could be harder than the ones manufactured today.

    Well, I hope that's not Toooo Creative, because it makes sense TO ME.

    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

  5. #5

    Default

    Quote Originally Posted by grousehunter View Post
    Was sizing some brass for my 300 weatherby tonight and started looking for load data to work up a load for it. I checked both the Nosler and Hornady manuals. One listed a load for IMR 7828 as starting at 80.5 gr with 84.5 being max the other listed 81.9 as the max load. This same thing was happening for more than one powder that I looked at. What gives????? Which data do you believe???? This data was for 180 grain bullets.
    I find that very easy to believe. Check the brands of cases and primers they're using. I'll almost guarantee that they're different. It's easy to affect "max" load that much with a change in either.

    Worse yet, your gun is likely to be different than the one used in testing, just like the others have pointed out.

  6. #6

    Default

    Good topic here.

    I found a similar situation with Nosler and Hadgdon data that I posted in another thread

    If you visit the Nosler and Hodgdon sites and check the data for 300 RUM/200 gr AB using IMR 7828, you will find a huge differenc in their data.

    Hodgdon max -82.0gr/2857 fps
    Nosler max - 87.5 gr/3102 fps

    The Hodgdom max is lower than the Nosler starting load of 83.5.

    What do I conclude form cases like this? I treat loading manual data as a guide. If I have no experience with a particular bullet/powder combination I do a lot of research and try to get as much data and info as I can. Be conservative and carefully work up. I use what I consdier as the tangible pressure signs of bolt lift, primer and brass condition. There is a lot of disagreement on this subject, but I personally dont *rely* on a chrony as a pressure indicator for a lot of reasons, not the least of which is that their output will vary significantly from unit to unit.

    Bottom line... unless you have actual pressure reading equipement, you and all the rest of us are just guessing using the limited information we have as to where the pressure thresholds are.

    Take care,

    -MR

  7. #7
    Sponsor ADfields's Avatar
    Join Date
    Nov 2008
    Location
    Missing Palmer AK in Phonix AZ.
    Posts
    6,416

    Default

    As everyone has said the little stuff makes a big difference in pressure testing even air temp and barometer readings largely affect test outcomes. This is why they build a safety factor into the data they publish and since not all publishers use the same safety margins even if their tests gave them the same raw data what goes in the book will still differ. So if it looks like a guessing game that’s because it largely is, they test to find what is too much, and then take an educated guess at what would be safe if everything went wrong and print loads from that in mind.

    If one follows the "start low and work up" rule, minds the particulars of bullet, primer, and case then any published data should be safe to work from. Going too low on some powders can also give an over pressure and for this reason it’s best to ‘stay between the lines’ or keep within the published data you are working from. It’s not always possible to find data for an exact bullet or something and then we as reloaders must be extra cautious as we work something up from data that is as close as we can find.

    To me this is the stuff that makes it fun to be a reloader, anyone can pull a lever and assemble rounds but there if far more to it than just assembling rounds.
    Andy
    On the web= C-lazy-F.co
    Email= Andy@C-lazy-F.co
    Call/Text 602-315-2406
    Phoenix Arizona

  8. #8
    Member shphtr's Avatar
    Join Date
    Apr 2006
    Location
    Chugiak
    Posts
    1,376

    Default

    Start low and work up is always good advice. Regarding the new Nosler Manuel - they only offer one set of "guidelines" for reloading a particular bullet weight. Currently they offer multiple bullets several of which differ widely in construction. As a consequence I view their recommended "max" loads as somewhat soft given that the max. recommended limit has to serve several bullets and therefore the limit given is prob for the lowest limit for the multiple different bullets they give recommendations for. This is an intuitive interruption on my part and I have no evidence to substantiate this conclusion.

  9. #9
    Member
    Join Date
    Apr 2006
    Location
    SwampView AK, Overlooking Mt. Mckinley and Points Beyond.
    Posts
    8,810

    Default

    Quote Originally Posted by MontanaRifleman View Post
    Good topic here.

    I found a similar situation with Nosler and Hadgdon data that I posted in another thread

    If you visit the Nosler and Hodgdon sites and check the data for 300 RUM/200 gr AB using IMR 7828, you will find a huge differenc in their data.

    Hodgdon max -82.0gr/2857 fps
    Nosler max - 87.5 gr/3102 fps

    The Hodgdom max is lower than the Nosler starting load of 83.5.

    What do I conclude form cases like this? I treat loading manual data as a guide. If I have no experience with a particular bullet/powder combination I do a lot of research and try to get as much data and info as I can. Be conservative and carefully work up. I use what I consdier as the tangible pressure signs of bolt lift, primer and brass condition. There is a lot of disagreement on this subject, but I personally dont *rely* on a chrony as a pressure indicator for a lot of reasons, not the least of which is that their output will vary significantly from unit to unit.

    Bottom line... unless you have actual pressure reading equipement, you and all the rest of us are just guessing using the limited information we have as to where the pressure thresholds are.

    Take care,

    -MR
    How much variation in “unit to unit” chronograph output are you talking about, or consider significant?

    IIRC, a 30-06 180 Grain Factory Load, and most handload data says the max is around 2700 fps.

    So, if you got, say 3100 fps from a handload WITHOUT Pressure Signs, would you consider it safe? Or, to put it another way, don’t you consider Velocity to, at least, some degree?

    It seems to me that “velocity” even obtained with an imperfect chronograph, is a figure that is ‘tangible” and useful, to determine a SAFE load. ( If you get WAY more than everybody else, (Factory, Handload Data) shouldn’t you consider THAT a Pressure Sign, too? )

    Other pressure signs may not show, may not be judged the same way by different people, and will be different in each gun.

    How can you call that tangible? It is only recognizable, and it only means TOO MUCH. How much pressure does a tight bolt indicate? Or a flat primer? Or swelled brass? Or all of them? Or a combination of them? You have no figure, other than velocity.

    Velocity isn’t an indication of actual pressure, but if it is ballpark, it is an indication of pressure that is very likely to be SAFE, in most guns.

    Isn’t there, at least some point, where you really use BOTH, pressure signs, AND velocity?

    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

  10. #10

    Default

    Quote Originally Posted by Smitty of the North View Post
    How much variation in “unit to unit” chronograph output are you talking about, or consider significant?

    IIRC, a 30-06 180 Grain Factory Load, and most handload data says the max is around 2700 fps.

    So, if you got, say 3100 fps from a handload WITHOUT Pressure Signs, would you consider it safe? Or, to put it another way, don’t you consider Velocity to, at least, some degree?

    It seems to me that “velocity” even obtained with an imperfect chronograph, is a figure that is ‘tangible” and useful, to determine a SAFE load. ( If you get WAY more than everybody else, (Factory, Handload Data) shouldn’t you consider THAT a Pressure Sign, too? )

    Other pressure signs may not show, may not be judged the same way by different people, and will be different in each gun.

    How can you call that tangible? It is only recognizable, and it only means TOO MUCH. How much pressure does a tight bolt indicate? Or a flat primer? Or swelled brass? Or all of them? Or a combination of them? You have no figure, other than velocity.

    Velocity isn’t an indication of actual pressure, but if it is ballpark, it is an indication of pressure that is very likely to be SAFE, in most guns.

    Isn’t there, at least some point, where you really use BOTH, pressure signs, AND velocity?

    Smitty of the North
    First off, I dont have and never will have a 30.06 Next, If my chrony was showing 3100 fps for a 30.06 load with a 1800 bullet I know it would be broke

    I have read numerous reports that chronys can be off up to 3-5%. 3% of 3000 fps = 90 fps. If one was really going to use velocity as an indicator of pressure limits then one should probally throw that factor into the mix just to be "safe" and back off 90 pfs as your limit... wouldn't you think so???

    And.... just whose data are you going to use? In many case, if you go from one manufacturer to the other (like the previous example), their data will vary and in many cases it might vary over 100 fps and "x" gr of powder for the same cartridge. Which is right? Which will you subjectively choose?

    Manufacturer's data is derived from shooting through their test barrels. Do you know the chamber and throat dimensions for their test barrel? Do you use the same brass? Do you size your brass the same way and to the exact same dimensions? Do you use the same neck tension? Do you crimp your loads? Do you ever use a differnt primer than specified by the published data? Do you ever use a different COAL?

    One of the big reasons I handload is to be able to taylor a particucar round to "my" rifle, which means I may try different primers, brass, COAL's, neck tension, etc. All these variations can and will affect the presure/velocity ratio.

    If all rifles shot all brass/primer/powder/bullet combinations the exact same way and all published data were the same, and chrony's were guarenteed +/- 1%, then I would look a lot more closely at the chrony velocity as an indicator of pressure. Until then I will use What I think is the *most" tangible evidence of pressure... the ones I can see and feel. It's not a perfect way to determine pressure, but IMHO it's the best way if you dont have pressure equipment.

    -MR

  11. #11
    Moderator
    Join Date
    Jan 2005
    Location
    Midwest
    Posts
    4,431

    Default

    I think I'll agree with Smitty on this, if I undrstand his position correctly, but MR has some good points too. And shphtr's advice is start low and work up, is aways sound but there are lower limits too, as Andy said..

    I don't think most handloaders ever learn to read brass pressure signs accurately. I'm not sure I can either but brass is not always cooperating.

    A chronagraph is pressure indicating device.

    All the factors must be the same before you can say your load is the same as the one in the book.

    Bullet make, model, and lot #.
    Powder make, model and lot #.
    Brass make, model and lot #.
    Primer make, model and lot #.
    Same rifle with same chamber NOT just same make, model, etc.
    Then the atmospheric conditions and possibly the sign of the moon.

    The loading manual is accurate indication of what happened when the controlled lab shot that combination of components in their rifle, nothing more. In other words it is a guide or at best a small bit of history.

    You must conduct your own lab experiment if you don't have the same lot#s, etc.

    It is like flying a plane. It is certified to do certain things when you do certain things, with this weight distributed on board, etc. When you fly it with hole in the skin or 500 pounds of ice on the leading edge, or with a different propeller, you are flying an experimental aircraft, until that configration is certified in another lab. Some aircraft are not certified to fly with floats and those that are will have a different set of rules when on floats. Loading your own recipe with no data refference is very similar, but keep in mind, we do have test pilots among us.

    After shooting a few hundred rounds of different loads, in ol' Betsy, through a chronograph, you start to get a feel for what is a mild load and what is not. A true fact of pressure and cartridge brass is that it doesn't show pressure differences as small as about 10,000 psi. If that is an accurate number you could easily be 10 K over max with a normal load. Sure ol' Betsy will take it......today.

    A chronograph would be handy as a pressure indicator and if you see a 100 fps jump in veloccity from the norm in a load of the same weight, I'd say it is too hot. But there is more than that.

    If you shoot every load through (five of each) at, say, one grain increases you'll know what to expect for the next increase. (this isn't linear but there is a pattern). You will see a measured increase per grain of powder. When the increase per grain drops to half the peak, then you are over the optimum pressure burn for that propellant, then you are over pressure.

    If we plotted this with the velocity increases vertical, the peaks would form an arc, the base would be the initial velocity. The velocity increase per grain would be more for each powder increase (if you start below a normal load) until it peaks then would be less as we over charge. When it is back down to 50 % of the peak, back off to the next full grain, then work up and down with that at 1/2 grain jumps, not to exceed that last load. If that doesn't make sense, sorry. Oh, I do think good chronagrpahs are much more accurate than 1 %.

    It is like cutting a board with a saw to fit a certain notch, with no way to measure it (we don't have a lab). You cut and try to fit. Each time getting closer but careful not to cut too short. You wouldn't just cut it in half with the first saw cut, you would ease into it, gracefully.

    I think when several of us have done this reloading thing safely and sensibly for so long, we develop a feel for it and even though we can't just throw a dart at the powder shelf to pick a powder, we develop a good touch for what powder to use for each caliber. Along those lines, when we've used everybodys' bullets, we find the characteristics of each and know you can't use the same powder charge for the A-frame as for the Partition. You can't use the same powder charge for the InterBonds as for the Barnes TSX, etc, Ad Nauseum.

    It is really difficult to spread this experience through any writing but l I'm full of analogies this morning...well full of sumpin.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



  12. #12

    Default

    http://www.centerfirecentral.com/articles/pressure.htm

    This may be usefull as you work up loads

  13. #13
    Member
    Join Date
    Apr 2006
    Location
    SwampView AK, Overlooking Mt. Mckinley and Points Beyond.
    Posts
    8,810

    Default

    Quote Originally Posted by MontanaRifleman View Post
    First off, I dont have and never will have a 30.06 Next, If my chrony was showing 3100 fps for a 30.06 load with a 1800 bullet I know it would be broke

    I have read numerous reports that chronys can be off up to 3-5%. 3% of 3000 fps = 90 fps. If one was really going to use velocity as an indicator of pressure limits then one should probally throw that factor into the mix just to be "safe" and back off 90 pfs as your limit... wouldn't you think so???

    And.... just whose data are you going to use? In many case, if you go from one manufacturer to the other (like the previous example), their data will vary and in many cases it might vary over 100 fps and "x" gr of powder for the same cartridge. Which is right? Which will you subjectively choose?

    Manufacturer's data is derived from shooting through their test barrels. Do you know the chamber and throat dimensions for their test barrel? Do you use the same brass? Do you size your brass the same way and to the exact same dimensions? Do you use the same neck tension? Do you crimp your loads? Do you ever use a differnt primer than specified by the published data? Do you ever use a different COAL?

    One of the big reasons I handload is to be able to taylor a particucar round to "my" rifle, which means I may try different primers, brass, COAL's, neck tension, etc. All these variations can and will affect the presure/velocity ratio.

    If all rifles shot all brass/primer/powder/bullet combinations the exact same way and all published data were the same, and chrony's were guarenteed +/- 1%, then I would look a lot more closely at the chrony velocity as an indicator of pressure. Until then I will use What I think is the *most" tangible evidence of pressure... the ones I can see and feel. It's not a perfect way to determine pressure, but IMHO it's the best way if you dont have pressure equipment.

    -MR
    I think that 3100 fps with a 180 grain bullet in a 30-06 is possible, but not without unsafe pressures, with or without, pressure signs. ???????

    I’ve no objection to adding chronograph issues, real or perceived, into the mix.

    I would pay closest attention to the data that is the closest match to the components, I’m using, but consider it all, and find a starting point.

    I would consider the velocities obtainable with the particular cartridge, and when I reach them, according to my Chronograph, reckon that I’m ( pretty close ) to the Max Safe pressure for the cartridge.

    I don’t think that “all rifles” HAVE to shoot “all brass/primer/powder/bullet combinations the exact same way” and all published data be the same, for it to be meaningful. I’ve handloaded WITHOUT using a Chronograph too. And, of course, I watch for pressure signs too. Don't we all?

    I agree there are a LOT of variables, but the DATA tells us the PERFORMANCE we can expect from a particular cartridge. I figger they’re gonna wring out, about as much as they can get, SAFELY.

    I wanted you to say that YOU DO, consider velocity, and wouldn’t go far beyond the performance the cartridge is designed for just because of an Absence of Pressure Signs, like the ones you mention.

    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

  14. #14
    Member marshall's Avatar
    Join Date
    Nov 2007
    Location
    Near Phoenix, AZ
    Posts
    1,814

    Default

    This post swayed away from the original question a bit. So based on that consider reading the information in the link below.

    http://www.frfrogspad.com/loaddev.htm

    Based on some info that Murphy passed along in a post a little over a year ago I researched sine waves and barrel accuracy achieved along multiply points of velocity in a barrel prior to achieving max loads. I feel this article hits just that in step 1 and step 2 that may explain this better than I.

    For example, when loading I achieve average, good and great groups as I work incrementally towards max load. As I continue until max pressure shows up I sometimes have two loads that are great and one is generally 125-175fps faster than the other. That would be my load of choice and bullet seating depth changes would be my next area to tweak.

    The chronograph is a great tool when developing loads. If you develop a base line, (velocity divided by charge) you can plot performance and know what each increase in powder will achieve until you approach max load. As you get there performance starts to deteriorate before max pressure arrives, this is when it becomes time to be more careful. I generally increase in .7gr increments and drip to .3gr increments as max load approaches.

    In my .375 I have a few good loads with a couple of powder, primer, bullet combination's using 260gr Accubonds and 270gr TSX's. I have not been able to develop a 300gr load that shoots faster than 2520fps with accepable accuracy of the slow load. Testing with RL-17 is coming soon, that may be the answer if claims of increased velocity over H4350 with similar charges is true. If true I may hit the next accuracy point along the sine wave.

  15. #15
    Member 1Cor15:19's Avatar
    Join Date
    May 2009
    Location
    Dillingham, AK
    Posts
    2,482

    Default

    Quote Originally Posted by MontanaRifleman View Post

    I have read numerous reports that chronys can be off up to 3-5%. 3% of 3000 fps = 90 fps. If one was really going to use velocity as an indicator of pressure limits then one should probally throw that factor into the mix just to be "safe" and back off 90 pfs as your limit... wouldn't you think so???

    -MR
    I am not aware of a means to calibrate or verify the accuracy of a chronograph, but I am all ears if you have some information in that regard. I have used an Oehler 35P for many years now and while I can't testify to its accuracy I can say that the proof screens register remarkably similar velocity (normally withing 5-8 fps) and I have used it to "test" other cheaper chronographs. I do not recall a chronograph that has registered even 2% variation with the Oehler. I use a chronograph with every bench fired shot and have gravitated towards a Competition Electronics model because of convenience and ease of set up. It has always displayed velocity within 1% of the Oehler and so I never had a reason to not trust its readings. I am reluctant to trust any single reading that is off by more than 2 standard deviations, but using several 5 or 10 shot strings I believe that I have an accurate understanding of real world velocity. If you are concerned that you're chronograph is prone to error from 3-5% I would invest in another, perhaps several, and compare them to find a model you can trust to reliably report your cartridge's velocity.


    A chronograph that has a 5% error might explain some of your velocity advantage in the 300 WSM though .

  16. #16
    Member marshall's Avatar
    Join Date
    Nov 2007
    Location
    Near Phoenix, AZ
    Posts
    1,814

    Default

    Quote Originally Posted by 1Cor15:19 View Post
    A chronograph that has a 5% error might explain some of your velocity advantage in the 300 WSM though .

    Roger that!

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •