Case length

[Jim_Fleming]

armyrat:

What happens is that the recoil of the firearm actually pulls the brass off of the bullet.

For example: Since the brass of a .357 Magnum case is somewhat lighter than the bullet, it's easier for the brass to be moved backwards during the recoil than it is for the bullet. Yes the bullet is for a fact subjected to the exact same recoil, but inertia comes into play here.

Think of a stalled car... When someone is trying to move that car by hand you know that it takes much more effort to start the car moving than it does to keep the car moving.

Same thing with the casing of the cartridge versus the bullet, it's easier to start the case moving than it is to get the bullet to start moving.

Jim

[Echo]

But hot pistol rounds should be nicely crimped - maybe even heavily crimped. That ol debbil inertia...
Rilfles typically are heavier, so there is more mass to absorb the recoil, thus less chance for bullet expulsion.

[Jim_Fleming]

Echo, thank you for saying so... I guess after re-reading my post I did for a fact forget to say that rounds of that nature need to be crimped...

Thanks again, Sir.

Jim

[armyrat1970]

armyrat:

What happens is that the recoil of the firearm actually pulls the brass off of the bullet.

For example: Since the brass of a .357 Magnum case is somewhat lighter than the bullet, it's easier for the brass to be moved backwards during the recoil than it is for the bullet. Yes the bullet is for a fact subjected to the exact same recoil, but inertia comes into play here.

Think of a stalled car... When someone is trying to move that car by hand you know that it takes much more effort to start the car moving than it does to keep the car moving.

Same thing with the casing of the cartridge versus the bullet, it's easier to start the case moving than it is to get the bullet to start moving.

Jim

Jim thank you. Understand. Does this theory hold true for cast boolits as you have no crimp groove? At least not the ones I cast. I can apply a crimp in the lube grooves if needed. But I think they would still have some slack. Would proper neck tension itself be enough to stop the cast bullet from pulling out of the case from inertia. My Lee dies apply a roll crimp. I may possibly have to get the Lee Factory Crimp Die to apply a crimp on the bearing surface depending on bullet seating for correct OAL.

[versifier]

Usually, when a cast bullet is properly sized for the bore, it is greater in diameter than a jacketed bullet for which the neck expanders in the dies are designed. This means that there is quite a bit more neck tension than there would be with a jacketed bullet. That said, it is often necessary to crimp a cast load anyway (especially a rifle load) for uniform ignition with the reduced powder charges used, even in a bolt action or single shot which normally wouldn't require it. You have to experiment with the load and the firearm though to see if the recoil is enough to pull the bullets and if crimping makes a difference in accuracy (which, even in a Contender/Encore it often does).

[Jim_Fleming]

Yes, ArmyRat, in *MY* opinion only.

If you're shooting a straight walled case, when you "bell-mouth" the case you need to crimp it anyway... So even if you were using a jacketed slug, you're going to "crimp" the case against the side of the bullet, whether you crimp into a cannelure, a crimping groove (most cast pistol bullets have a groove) or simply seal the case against the side of the bullet. I realize that doesn't answer your question completely.

But, I think, NOTE I said think, that when you're using cast rifle bullets that the same principle applies. I've never shot cast bullets in any sort of rifle. For that matter I've never cast rifle bullets.

If you're shooting reduced loads in a rifle, I would *think* that the recoil isn't going have the same level of effect, since you're not going to be shooting a heavy magnum load, etc.

But to tell the truth I am convinced there are some *HIGHLY* experienced cast bullet rifle shooters on here that can definitively answer your question, where as I'm almost guessing here.

Hope this helps,

Jim

Jim thank you. Understand. Does this theory hold true for cast boolits as you have no crimp groove? At least not the ones I cast. I can apply a crimp in the lube grooves if needed. But I think they would still have some slack. Would proper neck tension itself be enough to stop the cast bullet from pulling out of the case from inertia. My Lee dies apply a roll crimp. I may possibly have to get the Lee Factory Crimp Die to apply a crimp on the bearing surface depending on bullet seating for correct OAL.

[runfiverun]

quite often with rifles the act of chambering a round will engage the nose into the rifling if you have enough neck tension the boolit will not be forced back into the case and the engagement will act much like a crimp.
now the rub some boolits don't like that much neck tension [you might actually be sizing the boolit smaller with the tension]
you gotta really mess with rifle boolits sometimes.
fit is king but even when you think you have the perfet fit they still won't shoot well.
if the cast boolit you are talking about is a lee with all those micro bands they are all crimp grooves.
other boolits you just crimp over the driving band on the front.
i have some of lees 240 gr swc's with the microbands i seated in 44 special cases and had 2 of them with messed up primers and i can't beat them out of the cases with a hammer type puller and i am afraid to mess up the brand new cases. they have no crimp on them.