Author Topic: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?  (Read 17647 times)

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ARTINCT

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Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« on: December 04, 2009, 10:14:51 am »
Hi Guys:

Pretty simple question....

How much taper crimp should I have adjusted in for .45 ACP in a light Bullseye Load.

I am loading with 4.1g of Hodgdon's CLAYs in Winchester brass with the large flash holes.

The bullet is a home cast .452 Star Lubrisized Hensley & Gibbs 200g Semi Wad Cutter Bevel Base from a #68 mold.

Currently, my taper crimp is set up to apply .470 to .471 taper crimp with .021 - .025 of the bullet shoulder above or exposed from the brass.  Variance of the shoulder probably due to brass length + or -

Now I have not done any testing with variance in taper crimp.  I do not experience any bullet movement
due to recoil with the current amount of taper crimp from recoil of the slide.  All works fine and am getting 100% feeding in both my .45 ACP pistols.

So if I start a taper crimp test process with my ransom rest... where should I start with the "most amount" of crimp and what should the increment of crimp be?

For example: start at .465" and increment by .002...  .467  .469  .471

Just so you know... my bullets are a 20:1 lead tin alloy with a BHN of 10.
All are sorted by weight within .2 grains.  I kind of worry that too much of a crimp will
deform the bullet.

So any input you may have regarding the taper crimp amount with a light bullseye load would be
greatly appreciated.

Thanks So Much,
Art in CT
« Last Edit: December 04, 2009, 10:17:12 am by ARTINCT »
Art In Connecticut

CDRT

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Re: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« Reply #1 on: December 10, 2009, 11:18:33 pm »
I'm loading a 200 grain SWC from Bullet Works in Breckenridge (which is the same as your bullet) with 3.5 grains of Bullseye.  I taper crimp mine so the diameter is .472 and they work just fine.  I've been using that amount of crimp for a very long time and have never had any problems.
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NYKenn

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Re: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« Reply #2 on: December 10, 2009, 11:21:33 pm »
Differant brand but same specs as CDRT.

Works and shoots well. Very well. Better than me.
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NYKenn

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Re: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« Reply #3 on: December 10, 2009, 11:23:53 pm »
There is a copy of a Gil Hebard spec sheet uploaded by RBWillNJ in the topic  Star on Ebay.
Bruce commented on the suggested taper. He can propably provide some insight too.

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rbwillnj

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Re: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« Reply #4 on: December 11, 2009, 10:12:38 am »
I taper crimp my 45 ACP rounds to .469 at the case mouth.   My bullet is a cast lead semi-wadcutter sized to .452 in a Star lubesizer, and I use mostly Federal, and sometimes Winchester cases.

Now I have never tested to see if a tighter crimp would give better results, but I get consistant sub 2" groups at 50 yards with my load, so I'd rather spend my time shooting.

The Gill Hebard sheet recommends .460 to .463 and that seems really extreme.   I have never tried it, but I think it would take a lot of force to get that sort of crimp using hard cast bullets.  Maybe Hebard was using swagged bullets.
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Star73

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Re: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« Reply #5 on: December 11, 2009, 11:03:07 am »
I think the .463 is from work done by John Giles. He reportedly did extensive testing to determine the best taper crimp. Gil, Jim Clark, & Giles were preety from the same "class".

The last 2-3 yrs I have opened the crimp up to the same area as Bruce. I did it based on the appearance of bullets pulled for one reason or another. I didn't like the amt of damage and am trying to minimize it.

BUT; I just had my loads tested and the groups were terrible. We think the problem is bullet wt variation. The tester, an experienced shooter & smith recommends Giles crimp .465+ or -In the past I had cast myself & didn't have the problem of wt variation or poor group.

If this is confusing to you...it is to me also!?

Ron

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Re: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« Reply #6 on: December 11, 2009, 01:19:28 pm »
Ron

This is where you have to start out with process of elimination, especially if you change something.
Bullet weight, powder weight, crimp, etc. etc. I know I check random weight for each box of bullets I open to reload to see variance. Powder on the Star seems to remain remarkably consistent, as do dies.

A few years ago, my groups (Bullseye) started to open up to the point my consistent scores were starting to drop. Started with weights, etc. progressed to the gun. Turned out the barrel crown was the problem.

Of course it is never the last item ever considered. The shooter!

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starman

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Re: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« Reply #7 on: December 11, 2009, 02:47:24 pm »
.472 at case mouth with win brass 3.5 Bull 185 SWC H&G and that is with range lead it is a Clark 45 long slide my biggest problem is with the target they all go into the same hole at 25 yards that is why I always take my Clark 38 long slide but most of the time I end up with the same problem

daveb

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Re: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« Reply #8 on: December 11, 2009, 08:14:19 pm »
Taper crimping does help hold a bullet in place to some degree but its purpose is to help prevent the case mouth from catching on the hood of the barrel. Magazines that can feed empty cases are wonderful. Years ago magazine lips and followers that were set up for short, shouldered cast bullets were tougher to come by. It was common to see a hand raised at a match and a fellah holding up one hand while the other held a stopped gun with a case mouth ripped by the barrel's hood due to the cartridge leaping too high trying to enter the chamber. Had it leaped higher it would have been a stove pipe.

Quality mold makers and bullet manufacturers don't like diminishing a bullet's bearing surface any more than necessary. I haven't talked to Gil for years now, and I wonder why he still prints that. Whether revolver or semi auto square edges have a tough time passing each other they like to catch. Having the shoulder of the bullet slightly above the case mouth is another part of this same idea, to prevent catching.

The real answer if you have a properly throated gun and good magazines is to close the bell, make that black line go away and you're done. Its not a number really. Its watching the gap between the bullet and case mouth disappear. It will dwindle to a black line and then disappear. The case mouth is now laid back down against the bullet. simple as that

Quick burning propellants like Bullseye, N310, and such are not as responsive to a taper crimp as H-110 with a jacketed bullet and a roll, factory or whatever the latest flavor of strong hold that bullet against recoil or misfeeding type crimp.

mackamanf

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Re: Question: Amount of Taper Crimp for .45 ACP Bullseye Load?
« Reply #9 on: December 28, 2009, 01:51:06 am »
I did fairly extensive testing with a Ransom Rest a few years ago on this very question as I like to know the answers.  In my testing I found that accuracy would begin to fall off below .465" and over .473" taper crimp, so I use the middle of these numbers at .469" 

One factor to be aware of is that brass will spring back slightly when crimped from the initial forming of the crimp die.  Pure lead is a dead metal and has no spring.  Alloyed lead to harden it will have a very small amount of spring back, but far less than the brass.  Therefore, when we taper crimp, we are actually springing the brass AWAY from the bullet slightly.  The increase in bullet pull is primarily due to the taper itself and the purpose is to prevent the lead bullet from receding into the case upon recoil from firing previously loaded rounds.

Fred M.