Bullet crimp

[Tracer]

How necessary would it be to crimp bullets being shot in a 7600 remington?  For an autoloader or tubular magazined lever rifle I understand the need.  This question came up concerning non-cannuled bullets and not having access to a Lee factory crimp die in the correct caliber.  Thanks T.

[John Traveler]

Case crimp on bullets is needed to resist bullet-to-case movement in autoloaders against feeding impacts.  In tubular feed repeaters, the crimp also helps prevent bullet movement bullet-to-casehead impacts during recoil.

Both of these can be prevented without crimping if your bullet-to-case assembly is tight.  The usual way to get this tight assembly is with undersized case mouths, sealant, or both.

I've shot many tousands of rounds in military and sporter  autoloaders without crimping bullets.

HTH
John

[Iowegan]

The pump action 7600 has a similar loading mechanism to an auto loader. The reason for crimping is when you slam the slide home, the cartridge enters the chamber briskly then comes to an abrupt halt. This motion can be just like a kinetic bullet puller and will be more pronounced with heavier bullets. When you extract an unfired round, examine the cartridge to see if the bullets are moving forward from their seated position. If so, you will need to crimp. Most reloaders prefer taper crimping vs roll crimping, that way you don't need to worry about cannelures. Taper crimp dies are available in many calibers.

The other "fix" is to operate the slide slower so it doesn't slam home. This will prevent the bullets from moving forward.

In a revolver or a tube fed gun, recoil is the culprit for moving the bullets. This is a non-issue in a box magazine rifle.

[razmuz]

Get one of those Lee crimping dies and crimp everything.  It can only help, that's why all the ammunition companies do it.

[Iowegan]

Razmuz, Actually, the ammo manufacturers roll crimp their cases because they don't know what type of guns their customers will be using. To be safe, they do indeed crimp most everything.

Roll crimping rifle cases is not usually the best solution. Rifles tend to be more accurate when cases are not crimped at all. The case mouth should be squared and uniform thickness so it will release the bullet straight. When you roll crimp (like the factory loads), the case mouth and the bullet get distorted and accuracy may suffer. Of course there are exceptions for tube fed guns where a hard rolled crimp is essential. Taper crimping is a better but not always a necessary solution for rifle cases. It doesn't change the case length, maintains a square case mouth, doesn't distort the bullet, yet holds the bullet firmly.

There's really no need to crimp rifle ammo intended for a single shot or a bolt gun. Magazine fed lever, pump, and semi-autos guns may need a crimp to keep the bullet from jumping forward when the action is cycled. Often times they work just fine without a crimp.

[m14dan]

In tube mags I do recommend it but not all auto rifles need it. I don't crimp in my m-1 or m-14. I tried it in both but found it actualy hurt accuracy some. Both are well tuned match rifles. Very few people I know do it for these types. For your rifle I would suggest experimenting. If it's mag fed and the bullets are staying put without crimping them leave it alone. If you notice problems then crimp them.