Should I crimp?

[Chevy1080]

Ok I am new to reloading and do not have my reloading book I just bought with me. I am going to be reloading my 22-250 and my .300wsm bolt action rifles. Don't I just use a resizing die to get the neck to the proper diameter for a firm bullet seat? Why would I crimp?

 

[navyrad8r]

Chevy,
you are in the right place, tons of knowledge here to be had. yes your die will take care of resizing your neck back to proper size. take some time and troll through the reloading manual and you will get off to a great start. Are you speaking of roll crimping the projectile, or crimping the primer pocket? i am guessing that you are after crimping the projectile. Welcome to the Forum!
Cheers,
Doc Lane

 

[BoydAllen]

You wouldn't.

 

[fdshuster]

Chevy1080: If you are loading for accuracy, like most of us, you are most likely using match grade jacketed bullets made by Sierra, Berger, etc. Very few, if any of these bullets have a crimp groove, and attempting to apply any type of a crimp (taper or roll) will damage the bullet, at least to some degree, depending on the amount of crimping/smashing force applied. If you are properly sizing the case (necks) you should get the proper bullet pull to prevent any movement of the bullet in the case neck. After seating try pushing the bullet into the case by pressing down on a padded surface so as not to damage the tip. It should not move. A crimp is a must for a tubular feed magazine as on a lever action, and many believe in crimping for semi-autos, but in my opinion, there is no need to crimp for a bolt action.

 

[Chevy1080]

Chevy,
you are in the right place, tons of knowledge here to be had. yes your die will take care of resizing your neck back to proper size. take some time and troll through the reloading manual and you will get off to a great start. Are you speaking of roll crimping the projectile, or crimping the primer pocket? i am guessing that you are after crimping the projectile. Welcome to the Forum!
Cheers,
Doc Lane

Thanks for the info guys. I haven't got to the crimping of the primer pocket in the manual yet so I am not exactly sure as to what that is haha. Also, how much smaller than the bullet do you guys usually size the neck to? 1/32"?

 

[navyrad8r]

chevy,
you wont ever crimp primer pockets but may deal with them if you use military brass. your calibers won't require it. like the other fella's said roll crimping is usually for military/semiauto weapons. roll crimping projo will most likely damage today's match grade bullets, but could have hunting applications depending on the projectiles. as for neck tension that is a source of contention with many members but .002~.003 neck tension should do it.
cheers,
doc

 

[Kenny474]

Crimping is done for several reasons. First, if you have a tubular magazine, such as used with most lever actions, you need to crimp so the bullet is not pushed into the case. If you have a semi-auto, you should at least apply a light crimp, as the hard, fast chambering from most semi-autos can push a bullet inside the case should it hang up on the end of the chamber for some reason. And a bullet pushed into the case can produce dangerously high pressure, not what you want for a fun day at the range.
In my opinion, most any ammo used for hunting should be crimped as well. Ammo used when hunting often sees rough treatment, and even a fast follow-up shot from a bolt action can push a bullet into the case, again causing a dangerous situation. Most hunting ammo is not seated out so far as to touch the lands, as it is usually loaded to magazine length.
Crimping can actually raise the shot-start pressure, as will happen when you load bullets long enough to jam the rifling. In certain instances, the higher shot-start pressure from crimping can actually produce better accuracy. It's just something you need to experiment with.

But when you are simply going for best accuracy with a bolt action and your ammo will be in a controlled environment, and not banged around and chambered hard like what would happen while hunting, you will usually do better without a crimp.

If you are going to be hunting and plan to use bullets without a cannelure, but want to experiment with a crimp, use the Lee Factory Crimp Die. It will crimp any bullet, with or without a cannelure (crimp groove) and trim length of cases is not critical, as with a standard taper crimp like that which is machined into most seating dies. The Factory Crimp Die will never buckle a case, like can happen with a taper crimp, as the Lee die is actually a collet that squeezes the neck of the case into the bullet slightly. It is easy to use and set-up, and is very affordable.

As for neck tension, I don't feel it necessary to go any more than .002". Brass only has so much elasticity, and will actually just stretch if you try to use more than .002" neck tension, essentially expanding the neck with the bullet. And since bullets make poor expanders, you will hurt concentricity.

If you want to see why I feel this way, try this experiment. Seat a bullet in 5 cases, starting with .001 neck tension, and going progressively up to .005" neck tension, and then let them sit for an hour or two. Now, using a kinetic bullet puller, remove the bullets and measure inside neck diameter. They will all have the same diameter, .001 smaller than the bullet. This is because they only have enough elasticity to hold .001 tension on the bullet. Any more and you are simply expanding the case. I do believe you will get a bit more hold with .002" neck tension, but after that I feel there are diminishing returns and you will simply expand the neck.

Good luck and welcome to the forum. The guys and girls here are the best in the world. There is a wealth of information here unlike anywhere else you will find. Some of the worlds best gunsmiths and shooters are here, and will share information that is worth more than gold in the shooting world.

 

[bigedp51]

I agree 100% with Kenny474, he is using all his gray matter.

My 30-30 hunting loads always get the tightest crimps.

 

[RonAKA]

Forget about crimping bullets or primers. Not done with hunting or target loads. This is about the worst thing you could do for accuracy.

 

[bigedp51]

Forget about crimping bullets or primers. Not done with hunting or target loads. This is about the worst thing you could do for accuracy.

My 30-30 will argue the point because I once thought like you until my bullets were pushed back into the case. How many military rounds have you seen that didn't have crimped bullets and crimped-staked primers.

You need to take your gray matter out of the bench rest mode and switch over to the rough handling mode.

Also remember Kenny474 has one more gold star than you have. ;D

 

[JohnnyJohnson]

I only crimp for two guns my Winchester model 94 32 special and my 378 Weatherby. I find it unnessary on the rest.

Whoops I lied I crimp my shotguns.

 

[whiskey08]

i shoot alot of 223 in a semi auto, and dont crimp. lots of bullets get scarred up while feeding and ejecting but i have not had one get pushed in. (using lapua brass and redding fl sizer). Nor do i think u need to crimp for a bolt gun

 

[deadlyswift]

If shooting a semi auto use a taper crimp. Like Kenny said. The hard ejection and loading of semi auto's can put you into a dangerous situation! I have loaded enough ammo to have seen how different seating depths can and will cause pressure changes, and it can be dangerous! SAFTEY FIRST WHEN RELOADING!!! I never use a roll crimp for anything. Use a taper crimp! If shooting a bolt gun, I use no crimp for anything! Crimping defeats the whole purpose of neck tension, but a taper crimp is needed for semi autos for Saftey reasons! Also roll crimping is only going to give feeding issues with semi autos. A taper crimp is all that is every needed and only then would I taper crimp if shooting semi autos. A roll crimp is just bad news for accuracy, and feeding of a semi auto.
Mark

 

[spclark]

If shooting a semi auto use a taper crimp. (snip) I never use a roll crimp for anything.

You probably don't shoot revolvers much, do you?

Use a taper crimp! If shooting a bolt gun, I use no crimp for anything! Crimping defeats the whole purpose of neck tension, but a taper crimp is needed for semi autos for Saftey reasons! Also roll crimping is only going to give feeding issues with semi autos. A taper crimp is all that is every needed and only then would I taper crimp if shooting semi autos.

You'd find many skeptics among the numbers who shoot competition high power events with gas guns.

Taper crimp is useful for straight-walled pistol rounds & may have use for some bottleneck rifle cartridges also where little time or effort goes into brass preparation. The vast number of shooters I know use a sizing die & perhaps appropriate neck bushing to produce consistent, safe ammo for their rifles.

If the bullets you want to use in your 22-250 or 300WSM have crimp cannelures, I suppose you could roll crimp once you find proper dies to do it safely. Taper crimp is more common for rifle-only cartridges (if needed at all) and understand that the operation can reduce the bearing diameter of your chosen bullet(s) if done to excess. A little squeeze goes a long way.

 

[TRECustom]

Chevy1080, good thread. Welcome to the site.

I crimp heavy bullets in hard kicking revolvers to help keep a bullet from riding forward in its chamber and locking the cylinder up, probably when you most need it NOT to lock up!

U.S. military ball ammo is cannelured and crimped, but the NM ammo in 7.62 x 51 (M852), is not, and it was developed to fire in M-14's. Also, .45 ACP and some other semi-auto pistol ammo can't be crimped, because the round headspaces on the case mouth.

I crimp .460 Wby, .375 H & H, .45 - 70, .454 Casull, and am going to try canneluring and crimping some 300gr Smkhp's (with the C-H cannelure rolling tool) for a .338 x .378, just to see what effect it has on accuracy. In general, I would crimp on large caliber rifles or pistols to help hold heavy bullets under hard recoil, but would not crimp most ammo that is not for dangerous game, and no ammo meant only for maximum accuracy. I don't do any roll crimping, only taper crimping into a cannelured bullet. So far, I haven't been able to tell if crimping hurts (or helps) accuracy on the ammo that I do it on. I do have a theory that crimping large bore slow ammo like the .45-70 helps get more consistent ignition. Only a theory though. Something that's not a theory is that 405gr .45-70 bullets sure shake out easy in a kinetic bullet puller until they are crimped in. Partly because of the weight of the bullet and maybe because the .45-70 brass is thin.

Good shooting, Tom