RCBS competition die not consistent?


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Old 07-24-2012, 08:56 AM   #1
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Default RCBS competition die not consistent?

I'm loading 50 grain Speer TNT's into .222. All cases are trimmed to within 0.001 and yet my rcbs competition die (the one with the micrometer on it) is producing COAL which varies by up to 0.010 on about 1/3 of the completed round. Any ideas? It's a pain to load them up then have to use a kinetic bullet puller to get the bullet out and reseat to correct coal. Thanks.



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Old 07-24-2012, 11:31 AM   #2
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If you were to seat them .005 deaper would you still be in spec on the good ones? Would that pull in the 'flyers' to an acceptable length? I know that wouldn't really solve the problem. Sounds like something might be loose.



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Old 07-24-2012, 02:07 PM   #3
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This is happening because the ogive of the bullets you are using is not consistent. There is nothing wrong with the dies. I have this happen with bulk .223 FMJ bullets when I load up plinking ammo for my AR's all the time. I'm not getting .010 difference, but usually around .003 to .005 is somewhat normal. Winchester FMJ's are the worst. This last batch of Lake City 55 grain FMJ's have been the best, with as little as .002 variance.

I wouldn't worry about it. One thing I always do is clean the tip of the bullet seater plug with a paper clip, and a Q-Tip saturated with alcohol. Stuff can get packed up in it like paper lint from the boxes, etc. OAL differences of just .010 isn't going to effect anything unless you're seating at or near the lands. Even then take an average and seat .010 to .015 below that. You won't get much group dispersion or velocity change with that little variance. The only way around this is to seat deliberately long, then bring in each round individually to correct OAL. That would be a royal PITA.

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Old 07-24-2012, 11:06 PM   #4
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Many thanks for your thoughts guys. Will do a clean but suspect the ogive is the issue. It's a brand new die so guess there could be stuff up it. I guess I can always use the consistent rounds for when it matters and the ugly sisters for practice.
FYI I found an extra 70 fps just switching to cci -br4's from standard cci small rifle primers and groups tightened to .2.
The difference between no internal case prep whatsoever and a case which is primer uniformed and internally deburred is 180 fps with exactly the same charge of RL-7. Consistency went from a 80 fps spread on the no prep's to 20fps for the full prep'd cases over 10 shots. Think I'm getting there!

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Old 07-25-2012, 02:48 AM   #5
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Are you measuring off the tip of the bullet or the Ogive? Tip measurements are never consistent even with top quality bullets. If you want accurate OAL/COAL measure off the Ogive.

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Old 07-25-2012, 08:08 PM   #6
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Quote:
Originally Posted by steve4102
Are you measuring off the tip of the bullet or the Ogive? Tip measurements are never consistent even with top quality bullets. If you want accurate OAL/COAL measure off the Ogive.
And how do I do that as I am indeed measuring from the bullet tip?
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Old 07-25-2012, 10:19 PM   #7
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Quote:
Originally Posted by stephencollins View Post
And how do I do that as I am indeed measuring from the bullet tip?
http://www.sinclairintl.com/.aspx/pid=34014/Product/Sinclair-Insert-Style-Bullet-Comparator

These work well for that.



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