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Thread: RCBS Precision Mic

  1. #1
    Moderator stid2677's Avatar
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    Default RCBS Precision Mic

    I received a RCBS Precision Mic for my 325WSM. This is one of the best tools for reloading I've found. Within minutes I was able to measure the headspace on both my WSMs and check my brass that was ready to reload. I can now make my brass last longer by preventing overworking it. Also makes setting up your dies a snap. Great product.

    I also bought a new box of factory ammo for my 270WSM, the extractor was having a hard time locking on to them. I measured them in the tool and found them .006 shorter than SAAMI specs.

    1. Measures shoulder to base of shell
    2. Measures the freebore of your rifle
    3. Measures ogive of seated bullets.

    Using these 3 measurements, a handloader can manufacture a more precise round for any given rifle.


    http://www.midwayusa.com/viewproduct...tnumber=428614

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    Default Good Info

    Thanks for posting Stid, I was looking into this so now I can ask you more,

    Does that one caliber specific mic work for your 270wsm also or did you have to get one for that caliber also? It looks like 325 specific on the website?

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    It will measure everything but distance to ogive of seated bullets. The 325WSM, 300WSM and 270WSM all share the same case.

    Steve

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    Default gettin redundant?

    So I just bought a Hornady Straight OAL Gauge a few days ago, does a Headspace gauge addition cover the same or close to the Precision Mic you are now using or would I be getting redundant to get both?

    It looks really good like it covers the OAL question i had as well as headspace question as well as other questions I'll have soon?

    Is the Headspace gauge all I need, along with the OAL gauge or should I just find the precision mic for other measurements I'll eventually wish I could get?

    Also what does Ogive mean? Distance from lands?

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    Moderator stid2677's Avatar
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    Ogive is the radius of the curve of the portion of a bullet forward of the point of largest diameter.

    As I understand it where the bullet touches the lands when extended until contact is made.

    If I'm incorrect I'm sure someone will speak up.

    For me I like using the Hornaday OAL gauge, better than the RCBS BULLET Method. The Hornaday OAL gauge uses the bullet you are reloading and is easier to use, I also get more accurate reading with the Hornaday. They just don't make one for 325WSM

    Measuring OAL from an ogive reference is more accurate to me as opposed to measuring from the tip to the base.

    The BULLET that comes with the set can be used to setup your dies.

    I really like being able to measure shoulder push back very accurately.

    I would size and attempt to chamber and keep repeating until the brass chambered Okay.
    With this tool you know your rifles headspace and can size .001 to .002 under so your reloads chamber with some field crud.

    I'm no expert, still learning myself. I was able to answer many questions about headspace and case size very easily with this tool and found it well worth the money. I'm confidant that I will produce higher quality ammunition with this tool.

    Steve

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    Ogive is the curvature of the bullet nose.

    I HAD the Stoney Point, now Hornady, tools, All of them, and I was unable to get a consistent OAL from the OAL setup, so I GAVE them away, and Good Riddance.

    The Stoney Point tool is designed to measure any cartridge, if you have the correct bushings, but the RCBS Precision Mic, is specific as to each cartridge.

    I have an RCBS Precision Mic. for the 7mm RM, but I retired the rifle, and no longer load for it. I would say that it was not absolutely necessary, but it did work OK. And, for me anyway, it is far superior to the Stoney Point thingys.

    I have considered getting another for my 7x57. I have other ways to establish the OAL to the lands, that are simple, practical, and accurate, so I dunno, if I will ????

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    Quote Originally Posted by stid2677 View Post
    For me I like using the Hornaday OAL gauge, better than the RCBS BULLET Method. The Hornaday OAL gauge uses the bullet you are reloading and is easier to use, I also get more accurate reading with the Hornaday. They just don't make one for 325WSM

    Measuring OAL from an ogive reference is more accurate to me as opposed to measuring from the tip to the base.

    The BULLET that comes with the set can be used to setup your dies.

    I really like being able to measure shoulder push back very accurately.

    I would size and attempt to chamber and keep repeating until the brass chambered Okay.
    With this tool you know your rifles headspace and can size .001 to .002 under so your reloads chamber with some field crud.

    I'm no expert, still learning myself. I was able to answer many questions about headspace and case size very easily with this tool and found it well worth the money. I'm confidant that I will produce higher quality ammunition with this tool.

    Steve
    stid2677:
    Whatever works best for you is the way to go. You might change your mind too.

    The OAL to the lands never changes except as the throat in your barrel wears. No matter which bullet is used, it contacts the lands at the same diameter. There is a difference in OAL to the TIP, with different bullets, because the contact can be at a different place on different bullets. BUT, you can use ANY bullet to establish the length.

    IME, the RCBS tool establishes the length to the lands contact, MUCH more accurately, and consistently, than is possible with the Hornady, because there aren't as many variables to deal with.

    You can better measure "shoulder push back" with an empty handgun cartridge case, or something similar. (Than with the Hornady)

    One of the Sinclair Hex Nut type Comparators will measure bullet length or OAL to the Ogive better.

    And, of course, you can set your seating die from any cartridge you've established length for, no matter how it was done.

    The principal of the Stony Point/Hornady tools is sound, but IME, they don't work as well as the RCBS Mic, for getting a consistent reading, AND neither one of them is essential.

    I would hate to do without the Sinclair Nut, though.

    Smitty of the North
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    Default

    Thanks Smitty.

    I will refine my technique, I was having a difficult time with the tip of the device getting stuck in the lands.

    Thanks for the tips.

    Steve

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    Default Precision Mic

    A friend needed some 300 Win Mag reloaded. They were from two different rifles. Using the Precision Mic we were able to separate the cases as to which rifle they came from. One of the rifles was in Valdez so we fired the one that we had here in Fairbanks. This gave us a sample case and identified which weapon cases with that measurement came from. We were able to load the cases and get them to the right weapon with out pushing the shoulders back. We sent the ones out of town with the warning to check all cases for feeding. We were very conservative on our load data.

    I measured the case from my 300 Win and all three rifles had different chambers so to speak. I was surprised at the differences in the chambers. Precision Mic are pricey but for belted magnums they are the cats meow. IMHO


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    Default Comparator works how ?

    Smitty, I'm looking at what Sinclair says about this stuff in the short description of the tool and I get the Precision Mic pretty well but can't figure out how the Comparator works at all. Can you describe it ?

    Maybe also your simple, practical and accurate "other ways" to get OAL,

    I tried a few I had read about with not much confidence in my results so am trying to get this dialed in now with the right tools

    Thanks

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    Quote Originally Posted by kodiakrain View Post
    Smitty, I'm looking at what Sinclair says about this stuff in the short description of the tool and I get the Precision Mic pretty well but can't figure out how the Comparator works at all. Can you describe it ?

    Maybe also your simple, practical and accurate "other ways" to get OAL,

    I tried a few I had read about with not much confidence in my results so am trying to get this dialed in now with the right tools

    Thanks
    The Sinclair Hex Style Bullet Comparator that I like, is like a Hex Nut complete with the hole in the middle, but no threads.

    The flats have holes that are drilled out to the bore diameter of various calibers, 6 per NUT, if you will. To have all the calibers in common use, you would need to buy Both NUTs. There are 2 of them, but I have only one.

    You can use it to measure seating depth of a loaded round, or the length of a bullet, all by it's lonesome.

    If I wanna measure a 7mm Mauser round, for example, and record the OAL from the major diameter of the bullet to the case head, I put the bullet end in the hole on the flat that is marked "7" for 7mm, and measure from the opposite flat, to the case head with my Caliper, and I have a length.

    The same applies to bullet length, (from the major diameter), (.276, I think) except you are measuring to the bullet end.

    There are other tools, with comparators that fasten to a caliper, including the Hornady version. I just like the Sinclair Hex Nut best.

    As to my "simple, practical and accurate "other ways" to get OAL", I'm almost sorry I mentioned it, because they're not that easy to explain, accurately.

    There are various ways to determine the OAL to the lands in your particular rifle, without using a tool such as the Hornady monstrosity, the Sinclair bullet depth Tool, etc.

    You can seat a bullet long and chamber it, and the bullet seats against the lands, and can be measured, IF IT DIDN'T MOVE on ya. Most people have some way of making the bullet loose enough to move in the neck when the round is chambered, and tight enough so it won't stick in the barrel and lenghen when you take it out. I size a small portion of the neck. Some people split a sized case neck.

    Reportedly, some smoke the bullet or use a Sharpie on it, trying different seating depths until they can barely see marks from the lands on the bullet

    I posted this method a short time ago, and Iím pretty sure that others use it too, or I wouldnít have heard of it, or used it.

    ďA SIMPLE way, Iíve been using of late is to put a bullet in the chamber, and hold it there. (With a Pencil, if you have a Bolt Action rifle.

    Put a wooden dowel down the barrel to touch the bullet, and mark the dowel at the end of the barrel with a knife. Then take the bullet out, and close the bolt and push the dowel against the bolt, and mark it again.

    The Max OAL for (a cartridge with) this bullet is the distance between the marks. You can measure that with a Dial CaliperĒ.

    Whew!!!
    Smitty of the North
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    Wow, Smitty I think that is the longest post I have seen you make, you must hate typing as much as I do.

    I use a different but similar method. I remove the bolt and place a bullet in the chamber, then I rotate the rifle to point barrel down so that the bullet seats against the lands. I then fallow it with a cut off chunk of 3/8" bolt which has had the head cut off and both ends filed square. I then use the depth measuring bit on my calipers to get the depth measured from the back of the action at the forward edge of the notch for the bolt handle. I then take the bullet out of the rifle measure its length and add it to the previously measured distance and call that measurement A.

    Then I insert a fired and not resized case, and push it into the chamber as far as it will go. I fallow it with the same modified 3/8" bolt and measure the depth to the same point on the action. I call this measurement B.

    I then find cartridge overall length at lands = A-B.

    I will have to try the Smitty way and compare results. I suspect the way I do it is slightly more accurate but it does seem more time consuming, and frankly when most folks load 30 plus thousandths off the lands either way should be plenty accurate.


    Has anyone attempted to make there own Stony Point type gage. I have considered getting a 1/8" pipe nipple filing down the end and retreading to 3/8 fine thread, drilling out the inside to 1/4", and cross drilling and tapping for a set screw. I am not sure there is enough diameter in a 30-06 size case head to tap it for 3/8" fine thread though, I also worry about keeping the threads lined up well enough to keep the whole works in line. And yes I know they are not that expensive but it is winter time so I have time on my hands and I am cheap.

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    Default Got it

    Nice Job Smitty, I think I got it

    With all these options (as well as the Hornady OAL gauge i just spent $30 some bucks for ??) it will be interesting to see what I come up with

    How's this idea for you.... If my Best OAL .02 off lands is longer than the Mag length.....

    Have a "custom loaded for most accurate length" round in the chamber for hunting, and shorter ones that fit the Mag as the next four after the first round? Anybody do that?

    One shot as best is what we're all shooting for anyway right?

    "Can you tell I'm having fun with Reloading Yet?

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    Quote Originally Posted by bandhmo View Post
    Wow, Smitty I think that is the longest post I have seen you make, you must hate typing as much as I do.

    I use a different but similar method. I remove the bolt and place a bullet in the chamber, then I rotate the rifle to point barrel down so that the bullet seats against the lands. I then fallow it with a cut off chunk of 3/8" bolt which has had the head cut off and both ends filed square. I then use the depth measuring bit on my calipers to get the depth measured from the back of the action at the forward edge of the notch for the bolt handle. I then take the bullet out of the rifle measure its length and add it to the previously measured distance and call that measurement A.

    Then I insert a fired and not resized case, and push it into the chamber as far as it will go. I fallow it with the same modified 3/8" bolt and measure the depth to the same point on the action. I call this measurement B.

    I then find cartridge overall length at lands = A-B.

    I will have to try the Smitty way and compare results. I suspect the way I do it is slightly more accurate but it does seem more time consuming, and frankly when most folks load 30 plus thousandths off the lands either way should be plenty accurate.
    Hea'VEEE, That sounds a whole lot like the way the "Sinclair Bullet Seating Depth Tool" works. Check it out in their catalog. They say that it is more accurate than the Hornady Lock-N-Load tool, but harder to use. I have one, and I certainly agree with both of those claims.

    The "Smitty way"????, with the wooden dowel is not original with me, but I like it. It's simpler than the Sinclair B S T, but I don't think it's as accurate.

    Smitty of the North
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    Quote Originally Posted by kodiakrain View Post
    Nice Job Smitty, I think I got it

    With all these options (as well as the Hornady OAL gauge i just spent $30 some bucks for ??) it will be interesting to see what I come up with

    How's this idea for you.... If my Best OAL .02 off lands is longer than the Mag length.....

    Have a "custom loaded for most accurate length" round in the chamber for hunting, and shorter ones that fit the Mag as the next four after the first round? Anybody do that?

    One shot as best is what we're all shooting for anyway right?

    "Can you tell I'm having fun with Reloading Yet?
    IF, the "most accurate length" is that much more accurate, I suppose the idea could have some merit, but I doubt that would be the case. I would work on a load with an OAL that feeds through your magazine. (You could still experiment with seating depth, within that limit.) ???

    I don't think that .002 off the lands is necessarily the most accurate length. Also, I think you will have trouble knowing for sure that you are .002 off the lands, because it's hard to measure that close. Your .002 may actually be .005, or .006, for example, EITHER WAY.

    You could stick a bullet when you extract a loaded round from the chamber, when you think you're off the lands, but you AREN'T, especially one that has a long ogive, like a VLD type.

    I use .030 and I might go with .020 but not much closer with a jacketed bullet. Cast Bullets are another matter. I've still got a long ways to go as far as finding accurate loads, but I've come to the firm conclusion that there is a lot of BS written about that stuff.

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    Quote Originally Posted by NorthCountry View Post
    A friend needed some 300 Win Mag reloaded. They were from two different rifles. Using the Precision Mic we were able to separate the cases as to which rifle they came from. One of the rifles was in Valdez so we fired the one that we had here in Fairbanks. This gave us a sample case and identified which weapon cases with that measurement came from. We were able to load the cases and get them to the right weapon with out pushing the shoulders back. We sent the ones out of town with the warning to check all cases for feeding. We were very conservative on our load data.

    I measured the case from my 300 Win and all three rifles had different chambers so to speak. I was surprised at the differences in the chambers. Precision Mic are pricey but for belted magnums they are the cats meow. IMHO
    NC:
    I read your post last night and I've been thinking abut it ever since.

    It just so happens that I have THREE 7x57s to load for.

    In which case an RCBS Precision Mic, might provide me with some useful information.

    Thanks
    Smitty of the North
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    Default Stretching OAL affects pressure?

    So pulling back to reality a bit and staying inside my Magazine length I still have a bit of room to lengthen the OAL,from the book lengths

    I was reading a thread from '06 last night and if I read it right Murphy is making reference to "things that can affect pressure, as in Increase Pressure
    and one of them is

    If you set the bullet to a longer OAL

    Did i read that right (sorry I have no idea where it was maybe I can find it later, pg 50 or so of Hdldg forum) but is this a factor I should consider when for example

    a Hornady BTSP #2735 140 gr bullet can be seated out to 2.785OAL by the book (Lyman 49th -270wsm) yet, I have room to go out to 2.9 in my magazine, how much is this going to affect the powder charge numbers

    something to consider in maxing OAL and how does it factor in?

    I may be hung up on the OAL a bit but it seems a lot of the experienced guys put effort into it and the idea of "bullet jump" to the lands vs "meeting the lands" just .03 or .05 out seems like it would really make a difference

    Thanks Again ahead of time

    Oh Yeah, Murphy did you ever write that book? Yet?

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    Moderator stid2677's Avatar
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    Al,

    Think of bullet jump like this. When you drive your car up to a curb stop and let the tire just touch it. Then try to drive over it. You will notice that it takes a lot more power to drive over the curb. However, with just a small running start it takes much less power to drive over it.

    So if you are right at max .020 off the lands and then move closer to .002, you could overpressure.

    Barnes bullets like a lot of jump. On my Remington with a short magazine. I have found that Barnes TSXs tend to be more accurate seated as long as my magazine will allow.


    Steve

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    Default OK, good description

    Oh so he was probably referring to overpressure from "too much lengthening" Yeah, I get that picture well. I'm nowhere near that and don't plan on even trying for .02 off just seeing that number around.

    When I get home and messing around in the shop again I'll ask more.

    My recent loads (not fired yet) i went out to Mag max length (this was a bit beyond the book OAL for the bullet)and feel good about them. Will try this Hornady OAL gauge and these other ideas for information sake as to where the lands are but that is really interesting that you have found a bullet that likes a bit of a jump. When I get the lands length I'll probably stay within the book for OAL (after a few experiments) but wondering why they have that number (COAL) in the book for every bullet type if every rifle is different for length possibilities?

    Good description of the jump word it didn't really click to me that there would be such a thing allowed in chamber construction but I'm still just thinking it through and no time at the range to play right now, Thanks

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    Obviously, you can tune your load for OAL. I've not done much of that, myself.

    When you seat the bullet in, or out, farther, you change the case capacity, so that can have an effect, on the total picture.

    Seating the bullet against the lands, can cause more presure, than off the lands. Whether it's "overpressure" or not depends on the powder charge and other things.

    The Quickload program I messed around with for awhile, estimated additional pressure of 8,000 psi when the jacketed bullet was against the lands. (For what that is worth) ?????

    I think the reason some people advocate seating against the lands, or very close to them, is that the bullet MIGHT be better aligned, which can make for better accuracy. That is probably the case, at least SOME of the time. I don't do that, myself, for reasons I've already mentioned.

    When you shoot cast bullets in a rifle, I figger that it helps a LOT of the time. I've done it with cast bullets when it's a reduced load.

    Smitty of the North
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