I have still another question. Is crimping a good thing to do all the time? I bought a Redding die set for my 375HH and read that it is better to crimp as a separate function.

I bought a Lee Crimping Die for the 375 and plan to crimp half my bullets to try them. Does crimping make your loads less accurate? Would you crimp a 257 Roberts? Thanks in advance, Jeff

I remembered seeing this in another thread and thought it would answer your question quite well. It's from ricciardelli originally and I tend to agree with him.

Good luck,

Reed

quote:
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Originally posted by sll:
Steve,out of all of the testing you have done,have you ever experimented with crimped vs. non-crimped rounds?
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Yup...

And I have found the following to be the general rule:

For all semi-auto pistol cases (ie. 9mm, .38 Super, .45ACp, etc) a taper crimp.

For all straight-walled revolver cases (ie. .38 Special, .357 Magnum, .45 Colt, etc) a firm roll crimp.

For all single-shot pistol and rifle loads, no crimp.

For all tubular magazines, a roll crimp.

For bottle-necked cartridges in bolt-action, no crimp.

For bottle-necked cartridges in lever-action, pump-action, and semi-auto, a roll crimp if the bullet is so manufactured, if not, then a strong taper crimp.

For all full-auto, a strong roll crimp.

There are some exceptions to this...I taper crimp .30 Carbine, some .45-70's have no crimp (the ones I use in my Rugers) and some have a roll crimp (the ones I used in my Marlins).

In addition, a crimp may or may not be required depending on what powder you are loading. Basically I have found that all ball powders require a strong crimp to insure complete ignition.

I might add that you need to understand that for certain calibers you may not be able to crimp for headspace purposes. There are a few other rules of thumb but Steve pretty well hits them. If what he says doesn't make sense just ask another question.

Reed

Jeff this is strictly from my learnings as I am new too. Yes factory ammo is usually crimped. A good crimp keeps the bullet from getting pushed further into the case inside say a tubular magazine where the bullets have spring tension on them and they are nose to primer(example 30-30 Marlin or Winchester). Also I have been told that in a revolver the recoil, if loaded heavy, can cause an uncrimped round to seat deeper. I don't think it would hurt to crimp any ammo although if shooting in a bolt action or loading them singly in a lever action a crimp is not necessary. A crimp increases start pressure, therefore increasing pressure in general, because it takes that much more build up of force inside the case to discharge the bullet. Also as stated in the book Modern Reloading, hunting ammo is best crimped because of the rough handling it tends to take but for target shooting it is not necessary. Cory