Crimping. ??

[cocopuff]

Loading 38s and 357s with cast bullets.
Actually I have been loading off and on for several years.
Never thought much about it before but I'm loading for 38-44 now
How do you determine the proper crimp.
These are all cast bullets. I can't push the bullets any further into the case by hand.

Thanks,johnny

 

[Uncle Bruce]

Loading 38s and 357s with cast bullets.
Actually I have been loading off and on for several years.
Never thought much about it before but I'm loading for 38-44 now
How do you determine the proper crimp.
These are all cast bullets. I can't push the bullets any further into the case by hand.

Thanks,johnny

Do the bullets you want to use have a crimp groove? If so that would be a good place to start. You say you cannot push the bullets into the case any farther, is this because of the powder or the crimp you have done. The crimp is so the bullets don't move out of the case under recoil.

 

[K22]

Crimping pistol bullets is done for more than just so the bullet won't move upon recoil. It also facilities efficient powder burn. Years ago, Speer did a study of this validating this issue. Accuracy improved significantly with all loads crimped, including light target loads and there was less unburn powder.

There are two types of crimps, a roll crimp and taper crimp. While both can be used for revolvers, I found that the taper crimp to work best with hollow base wadcutters in light target loads for the 38 Special. Whereas for the 357 Magnum, especially with magnum loads, the roll crimp worked best for me.

The roll crimp should be applied in the cannelure portion of the bullet. But don't overdo it, what you are looking for is a smooth roll of the case mouth into the middle portion of the cannelure. This can be assessed both visually and by feel. You do not want to crush the case mouth or bulge the mouth which I have seen some reloaders do. When you run your finger along the case with a seated and crimped bullet, it should be smooth with no bulges.

If the bullet does not have a cannelure, then you should use a taper crimp. This requires the use of a taper crimp die. For other than target loads, you want a firm taper crimp. You can test the adequacy by push on the seated and crimped bullet to assess if there is any movement.

 

[markm87]

Dang it! I thought we were headed for a huge fight on the subject of Rifle Cartridge Crimping.

 

[hpshooter]

Never forget to trim your brass to the same length if you are going to crimp. I taper crimp light pistol and revolver rounds. Heavy revolver rounds get roll crimped.

Have never had a need to crimp rifle rounds have been able to prevent projectile movement via neck tension.

 

[Dimner]

Loading 38s and 357s with cast bullets.
Actually I have been loading off and on for several years.
Never thought much about it before but I'm loading for 38-44 now
How do you determine the proper crimp.
These are all cast bullets. I can't push the bullets any further into the case by hand.

Thanks,johnny

For cast bullets. Crimping is kinda of one of those things you may or may not have to do.

I agree with k22, that crimping can help with ignition. However that point might be moot depending on the relationship between your cast bullet diameter and the diameter you expand the case necks for seating your cast bullet.

Usually cast bullets are a thou or two over jacketed bullets size. If you are resizing your brass back to factory specs and seating your extra .002" diameter bullets in that brass with no other processing, the bullet becomes your neck expander and the brass spring back will most likely give you all you need tension wise under normal circumstances. I'm not sure of the recoil/criming needs for cast and revolvers, so it's best to crimp as you would for autofeed.. If you are loading for auto feed, utilize the crimping groove in the bullet design. Make some dummy rounds and choose an OAL that places the mouth in the proper location in the crimp groove. This crimp doesn't really give the cartridge much more neck tension. It ensures that the bullet cannot seat deeper due to the driving band above the crimp groove.

I use the crimp groove method in my 30wcf loads in my win 94. I'm not that concerned about recoil in the mag tube, but when loading from the tube up the loading lever to the chamber, is where there are possible problems that could cause the bullet to seat deeper of not crimped using the crimping groove.

If your cast bullet profile doesn't have a dedicated crimp groove, a lube groove can work just as well. The thing about crimp grooves....they are designed to be located at the best spot for that cartridge OAL.

Most of the time the cast boolit loading manual will have the most popular bullet mold profiles listed along with the data. They will (or should) give you the OAL that places the mouth in the crimping groove.

This all gets a little more murky if you are heat treating bullets. At that point other factors come in play. Below is a 45cal with lube in the lube groove and the crimping groove nearer the nose at the end of the driving band. That's where you would want to crimp so you have a cartridge that looks something like the picture at the bottom .

 

[kenhwind]

LSWC in the .357 are crimped on the forward driving band, because this is a .38 Special bullet and will be too long if crimped in the crimp groove.
I crimp by feel especially for a semiauto pistol.
You can obtain a certain about of taper crimp with a roll crimp die, but if you're taper crimping a dedicated crimp die is best.

 

[Dimner]

LSWC in the .357 are crimped on the forward driving band, because this is a .38 Special bullet and will be too long if crimped in the crimp groove.
I crimp by feel especially for a semiauto pistol.
You can obtain a certain about of taper crimp with a roll crimp die, but if you're taper crimping a dedicated crimp die is best.

I'd be shocked if there wasn't a LSWC bullet mold out there made specifically for the 38 special with the crimp groove in the right location. However I do fully understand and respect those that want to use a single mold for dual purposes and might not be able to utilize the crimp groove in certain scenarios.

Me however, molds multiply like rabbits and I usually end up with a half dozen for any one specific need.

 

[std7mag]

Dang it! I thought we were headed for a huge fight on the subject of Rifle Cartridge Crimping.

If it helps, I've found if your having accuracy issues with mono, that a taper crimp can help.

 

[cocopuff]

Do the bullets you want to use have a crimp groove? If so that would be a good place to start. You say you cannot push the bullets into the case any farther, is this because of the powder or the crimp you have done. The crimp is so the bullets don't move out of the case under recoil.

I guess it's because of the crimp. The bullet does not push in any farther by hand