Bullet Set Back.??

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toad
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Bullet Set Back.??

Post by toad »

While reading about the 6.5 mm Carcano I noticed the Italians had come up with an interesting way to prevent bullet set back. The case had a step in it that the bullet would rest on.
I've been concerned about set back when I reloaded; use the right bullet crimping dies, use bullets with cannelures, push test the reloaded round, gauge check them, etc. Now I'm wondering about maybe the "case could be prepped some how :?: Perhaps cannelure the case to make a shelf at the right point :?:
A number of rifle loads have the base of the bullet below the neck so you couldn't use a "shelf" on them. :?:
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JustinR
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Re: Bullet Set Back.??

Post by JustinR »

If you could do it, it would likely have to be done every loading, as the brass would expand and flow a bit each time it was fired. I'm not sure I'd want to work my case necks that much, because you'd have to trim the inside of the case neck while compressing it tighter than the normal neck expander diameter, or slightly crimp the neck at the right spot, which could be hit or miss.

Then, if you switch bullet brand, type, or weight, the "shelf" would likely have to be in a different spot.

After having so much trouble with crimping with Hornady dies, I've switched to Lee Factory crimp dies, and been very happy with the consistent results. My 300 blackout subsonic loads are within an inch at 50 yards when I got a chance to try them the other day.
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toad
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Re: Bullet Set Back.??

Post by toad »

Back in ye olde days I got my best results with the Lee and the Dillon crimping dies mostly for .45 acp.
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First Shirt
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Re: Bullet Set Back.??

Post by First Shirt »

Mike Dillon had an excellent point when he asked "Why do we seat the bullet and crimp it in the same operation?"

Just about everything I reload, I seat the bullet and then crimp it in a separate step. Makes adjustments a lot less fiddly.
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PawPaw
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Re: Bullet Set Back.??

Post by PawPaw »

I likewise seat and crimp separately.

But, I don't worry so much about setback. It happens, sure, but I'm not convinced it's a problem except in very limited circumstances where you're already pushing the pressure envelope of a cartridge. Capstick talked about it in his stories about Africa and said that he'd seen disastrous results with dangerous game cartridges where the cartridge had been on the bottom of a magazine and the magazine "tooped-up" before the last cartridge was chambered. At that point, the bottom cartridge might have been subjected to recoil for eight or ten shots and the bullet would sink into the case. Hot sun and high pressure and problems were noted.

I've seen setback on .45 ACP ammo when the same bullet was repeatedly chambered. I've fired that ammo with no problem, but the .45 ACP is a fairly low-pressure round.

For the common handloader, bullet set-back isn't a problem if neck tension is sufficient. We should, of course, be careful in our processes. Pay more than casual attention to your ammo and reject anything that looks out of the ordinary.
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toad
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Re: Bullet Set Back.??

Post by toad »

I remember pulling a bullet on a PMC .45 acp round. It was a pain to get it pulled. Inside the case I saw three evenly spaced same size black patches. I think it was tar and I assume it was machine applied. I never could figure out a way that I trusted to do the same thing using some kind of adhesive that would set up, retain the bullet, but not so secure as to cause a kaboom. :?:
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Frankingun
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Re: Bullet Set Back.??

Post by Frankingun »

toad wrote:I remember pulling a bullet on a PMC .45 acp round. It was a pain to get it pulled. Inside the case I saw three evenly spaced same size black patches. I think it was tar and I assume it was machine applied. I never could figure out a way that I trusted to do the same thing using some kind of adhesive that would set up, retain the bullet, but not so secure as to cause a kaboom. :?:
My guess is that stuff helps hold the bullet in place while it's on the way to the crimping station.
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Vonz90
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Re: Bullet Set Back.??

Post by Vonz90 »

I don't crimp bullets I'm reloading for use in a bolt gun. It reduces accuracy for no real advantage.

Nothing wrong with it in principle (and I crimp some calibres) but it is not generally required.
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First Shirt
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Re: Bullet Set Back.??

Post by First Shirt »

Actually, I think my accuracy is better with crimped loads, because the pressures are more consistent.
(Of course, this could be a case of "I may be wrong, but I'm not uncertain. ")
But there ain't many troubles that a man caint fix, with seven hundred dollars and a thirty ought six."
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Whirlibird
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Re: Bullet Set Back.??

Post by Whirlibird »

The black stuff is basically tar, used to waterproof the cartridge. Not to prevent setback.

Used to be, manufacturers said three times chambered and done. Because after that, the bullets were loosening and setting back in autoloading handguns.

A test some years back using . 38 special, the bullet was tested at various depths. When seated .030" deep, the pressures had effectively doubled.

Now imagine what that .40 or .357 Sig is doing.
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