to crimp or not to crimp?

[furtaker]

I'm sure this is an obvious yes but I'm asking anyway. I'm going to be reloading a 300 ultra mag. for a buddy of mine do I need to crimp the bullets? The reason I ask is Hornady only offers one bullet in the 180 gr. (sst) with a crimp ring around it. Any help appreciated!

[Alleykat]

No.

[VaFisher]

No, just because they furnish a ring does not mean one has to use it.

[furtaker]

You guys dont think the recoil will be enough to effect the oal on the ones in the magazine?

[Alleykat]

Nope. However, it'd be pretty simple to mark your first few loads at the case mouth. You could then see if the mark's moved during recoil.

[IllinoisCoyoteHunter]

You guys dont think the recoil will be enough to effect the oal on the ones in the magazine?

Not if he neck sizes properly.

[furtaker]

Thanks!!!!!!

[furtaker]

I guess I have one more question, When do you need to crimp then?

[tiberius10721]

ammunition is crimped to keep bullet in place and from moving back further into case.since i have only reloaded pistol ammo so far i do know this is nessasary for pistol rounds so the pressure does not get increased. I think with bottle neck rifle cartridges its not necessary.I wonder though is cartridges for an ar 15 or any other automatic rifle need to be crimped?

[ZX10Aviator]

here is a question, why would you not want to crimp them?

[IllinoisCoyoteHunter]

here is a question, why would you not want to crimp them?

Long range target shooting. I never crimp my .243 rounds because I go through multiple steps to make sure the the neck tension holding the bullet is absolutely consistent all the way around (At least I tell myself it is....). If I crimp, I am not guaranteed that the crimp will apply even tension on the bullet all the way around.

[ZX10Aviator]

I see, I have never not crimped, Ill give it a shot, my ammo is already very accurate, so maybe itll get better

[IllinoisCoyoteHunter]

I single feed them in a bolt rifle. I crimp in my semi rifles. I also crimp hunting rounds I know will be in my magazine.

[mkl]

I guess I have one more question, When do you need to crimp then?

When you have a 45-70 Marlin 1895 or similar tubular magazine rifle, shooting full power loads, with a 405 grain bullet or heavier.

That is serious recoil, and believe it or not the cartridges tend to get shorter, not longer, as the spring in the tubular magazine slams the three or four cartridges in front into the next cartridge ready to feed from the magazine.

[furtaker]

now i'm confussed, These will be hunting rounds in a bolt action, dont crimp or do? I've never crimped before but I've only reloaded for my 22-250. What calibers should you crimp ?

[IllinoisCoyoteHunter]

In your case, you should crimp your hunting rounds. These rounds may be loaded and unloaded several times before they are actually fired. Hunting rounds are subject to more abuse than say target rounds. My rule of thumb for crimping: Crimp rounds used in lever actions, semi auto rifles and all hunting rounds. When my buddies come over and load rounds with me for their rifles, I make them crimp them because I don't know how they are gonna abuse those rounds before they are fired. I don't crimp my target rounds because I handle them carefully and load one at a time when shooting them. It will never hurt you to crimp. If in doubt, crimp it. Some rounds, like the 45-70 must have a firm crimp.

[brickeyee]

ammunition is crimped to keep bullet in place and from moving back further into case.

Most of the resistance comes from the interference fit of the bullet into the brass case.
The ID of a sized case is smaller than the OD of the bullet.
Crimping (especially roll crimping) may add a little to the case spring.

[furtaker]

vafisher said the bullet doesn't have to have a crimp ring to crimp? I dont dought he's wright but why do they make some with the crimp ring?

[jamaica]

Crimp all ammo for revolvers, all ammo for tubular magazines, and all ammo for very heavy recoiling rounds, such as cartridges designed for dangerous African game. Also put a mild taper crimp on pistol ammo to close up the flare. On some semi auto rifles and pumps the bullet striking the ramp may move the bullet in some. If this is the case they should be crimped. For most everything else crimping is not required.

Never try to put a roll crimp on a bullet without a crimp ring or cannelure.
Never taper crimp so hard you deform the bullet. Just press the flared portion up tight to the bullet.

You can check things out easily enough. In a revolver six shooter load six, shoot 5 then take the last one out and measure it. Revolver bullets tend to come out, and it may bind up the cylinder if this happens. On a semi-auto, load one in the pipe by racking the slide and letting it go in fast. Then take it out and measure it. These usually go shorter because of hitting the ramp hard.

On rifles with a magazine that holds 5, shoot 4 then measure the last one.
These usually go shorter too because the recoil brings the gun back and smacks the bullets in the magaxine.

The only rifle ammo I have ever crimped is for the 30-30. I don't have any semi-autoloader rifles though, so no experience there.

I have used many bullets with a cannelure without crimping them. Often the cannelure is in the wrong place anyway for the OAL I wanted.

[bullspotter]

I dont crrimp my 300Rum loads, never had any problems. Im using barns tsx bullets.

[James R. Burke]

Alleykat has the best and fastest way to check. Just mark the ones in the mag, and see if they move. I never crimp, but I dont own any auto's either.