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New bullets = case gauge problem


tedahlenius85

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Switched to a different 9mm bullet and started loading. After making about 30 rounds I case gauged them with bad results. About 25% didn't pass the gauge. The bullet is a 145gr flat point . 356, 1.105 oal.

Didn't have any problems at all with the 10 thousand rounds of Frontier .355 147's RN.

I took a sharpie and thought I'd see were it failed.

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Is this related to OAL, crimp, or is it simply a bullet problem, inconsistency maybe?

Edited by tedahlenius85
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It's related to the exact part of the bullet that starts to grind up against the freebore of the chamber. Put one of those next to one of your 147 grain round-noses. The flat-point is, for lack of a better word, cylinder-shaped for longer than the RN is.

It's a bullet shape/OAL issue. Different profiles of bullet often require different OALs.

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I've tested it first in my barrel to get a OAL that worked for the new bullet. I had 1.125 for the RN, and 1.105 for this FP. I don't think I can load them shorter. My friend loads the same bullet at 1.110 without any problems.

I mean the bullet just passes through the case gauge by it self, but when it's loaded to a case it grinds on the ledge of the flatpoint. How so?

I'm thinking maybe the bullet isn't seating straight, a little canted bullet would grind on one side right?

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You'll have to back it down to 1.100", and try that - should pass The Plunk Test

in Your barrel - your friends barrel is different - unrelated to yours. :cheers:

Just make up ten or so, and I'll bet they all go ... Most of your rounds,

(80%) will make it thru at 1.105", but not all of them - so, you have to

back it down a bit.

Drop your powder charge 0.4 gr and work back up once you have an OAL

that works 100%, using a chrono, of course. :cheers:

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I can load Bayou 115gr RN to 1.14" in my 1911s. Acme 115gr RN can't go beyond 1.125". The shape is everything. I think I backed the Acme bullets off to 1.11" for my H&K P2000. H&Ks are, apparently, notoriously short-throated.

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The ones that doesn't fit the gauge don't fit the barrel either.

I think it's a problem with how some of the bullets are seating in the case. They are slightly canted to one side.. So that side of the bullet grinds to the barrel, and in the opposite side the top of the brass is grinding against.

Does that make sense?

If so, what do I do?

My friend is using the same bullets and his bullets doesn't seem to fail at all in my gauge, and he loads them a bit longer even. The bullet sits straight for him.

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Are you using a RN or SWC seating die?

If RN, try the SWC.

I shoot conical nose flat point .40 bullets and they seat much straighter using the SWC die than they do with the RN die.

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Are you using a RN or SWC seating die?

If RN, try the SWC.

I shoot conical nose flat point .40 bullets and they seat much straighter using the SWC die than they do with the RN die.

I'm using the SWC die. First thing I changed when switching from RN.

I'm gonna try swapping it back to RN and see if that makes it better for me.

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I was going to say that sounds like a seating die issue. Also, too much bell, possibly. .. possibly.

I subtract .015 from whatever my barrel plunks at. So if it plunked at 1.105, I'd run at 1.090. I've gone down to 1.100 w 147's RN and TG with no issue, so maybe there's a place to start, esp. if you're running FP.

Lastly, I learned real quick that the tolerances of CZ'S is so abstract, you can't compare to others.

Good luck, bud.

Edited by TJART
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