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Southern Shooter
03-17-2014, 10:26 AM
What types of crimps are these? These are from the Grizzly Cartridge company.
9975999760
454 Casull 300gr LFNGC............454 Casull 360gr WLNGC

99763

Tatume
03-17-2014, 12:34 PM
Very heavy roll crimps. Note the curvature, especially in the bottom photo. A taper crimp is not rolled into the crimp groove like that, and usually will be used on a bullet that doesn't have a crimp groove. Taper crimps are generally for auto cartridges, and roll crimps are for revolver cartridges and cartridges used in tubular magazines.

Char-Gar
03-17-2014, 12:53 PM
Yep, really fierce roll crimps. They don't want those bullet moving at all!

Southern Shooter
03-17-2014, 12:59 PM
Is the Lee Factor Crimp Die considered a heavy roll crimp?

Tatume
03-17-2014, 01:16 PM
Is the Lee Factor Crimp Die considered a heavy roll crimp?

That's up to the person adjusting the die. You can set it for anywhere from no crimp to way too much crimp.

Southern Shooter
03-17-2014, 01:20 PM
Does a heavy roll crimp greatly decrease the life of brass?

Tatume
03-17-2014, 01:22 PM
Yes, you will probably find your cases eventually cracking at the mouth. If you anneal them every five shots or so they will last much longer. However, I find that I usually get about 15 - 20 shots per case without annealing, so it's not a big deal.

Digital Dan
03-17-2014, 01:27 PM
Yes, those crimps are heavy. I would not and do not do that to lead bullets. Have been using a taper crimp on the .44 mag in a rifle since '99 or there abouts with no issues at all, save for very fine accuracy.

prs
03-17-2014, 01:41 PM
My opinion is that roll crimping beyond having the case mouth just pressed against the boolit down in the crimp groove is folly. Deforming the lead by crimping beyond that is likely to yield less retention than a normal crimp because the brass will rebound a little more than the lead.

prs

Southern Shooter
03-17-2014, 01:43 PM
Why do companies like Buffalo Bore, Grizzly Cartridges, and Double Tap use such heavy crimps?

William Yanda
03-17-2014, 02:02 PM
Why do companies like Buffalo Bore, Grizzly Cartridges, and Double Tap use such heavy crimps?

If a little is good, a lot is better?

MostlyLeverGuns
03-17-2014, 02:23 PM
With hard recoiling cartridges, the possibility of bullets pulling and tying the cylinder exist. If a particular cartridge is loaded many times and not fired, while 20 or 60 other hard recoiling cartridges are fired, the bullet might move. These folks worry about things like that. To check your crimping, measure overall length then fire 20 or 50 while that single cartridge sits in the cylinder. If length changes you must decide if the changed length is important to you? ?

Southern Shooter
03-17-2014, 02:29 PM
Does such a heavy crimp help with the ignition of some hard-to-light powders?

lwknight
03-17-2014, 03:01 PM
Theoretically speaking, a heavy crimp can effect ignition. However in my opinion, the bear country ammo is likely heavy bullets are in order so the heavy crimp will not have so much need as far as powder ignition goes.

Back to the bears. It would really mess up your day to have to actually use the rounds against an angry bear and have a bullet slip out enough to lock the cylinder from turning. So that is probably what the manufacturer was thinking.

I can see a 454 having a bullet moving problem but the 357 will not likely have an issue. My bullets have plenty of tension with only a moderate crimp but I do not have experience with 200 grain bullets either.

DougGuy
03-17-2014, 03:28 PM
That's not a roll crimp.

The cartridge on the left in the OP's first pic, is done with a Lee Factory Crimp die. It is a collet style die with four fingers that close from the side to perform the crimp, same as a collet crimp for a rifle cartridge. This die is uncatalogued but they still sell them. For heavy boolits they are great. They do shorten the life of the case as opposed to a roll crimp (which looks like the cartridge on the right is crimped with) but the real purpose of those type crimps is to prevent the boolit moving forward under heavy recoil. Lighter boolits don't need this degree of crimp but for a heavy boolit .44 Magnum on up into the .50 caliber rounds, this crimp works great.

I use this crimp for heavy boolits in a .45 Colt Ruger Vaquero over hefty charges of H110 and I experience zero boolit movement. What Grizzly is doing, is loading a heavy boolit intended for dangerous game, when you absolutely cannot afford the ammo to malfunction, as in the boolit jumping crimp even slightly, and tieing the gun up where the cylinder cannot even be rotated far enough to access another live round. With an angry bear or a razorback boar bearing down on me, that collet style crimp is just another bit of insurance that is very welcome in a situation like that.

Buffalo Bore also uses this type crimp for some of their more robust offerings.

Here is a thread detailing my use and modification of the collet style FCD:

http://castboolits.gunloads.com/showthread.php?201449-Question-about-type-of-crimp-required&p=2239315&viewfull=1#post2239315



Does such a heavy crimp help with the ignition of some hard-to-light powders?

It can make ignition more consistent, good ignition also relies on case neck tension and tension from the crimp to keep the boolit from jumping crimp when the primer lights off. In some cases, just the pressure and energy from the primer can move the boolit forward, effectively changing the case volume which will most certainly mess with the burning of the powder and the resulting pressure curve is totally different than what it should be.

bobthenailer
03-18-2014, 07:06 AM
Freedom Arms factory jacketed ammo is crimped with a heavy roll crimp like the 300gr lfngc in your picture.
I only crimp my full power jacketed bullets like it using a lee factory crimp die.
with my LBT 300gr lfngc boolets, and loads in the 1,400 to 1,600 fps range i use a redding pro crimp die as the bullet has a different style crimp grove than jacketed bullets.
And for loads in the 1,100 to 1,200 fps range with cast i use a lee taper crimp die.