Crimp mark on 357sig bullet acceptable?

[CaneCorso85]

Hey guys,

I am beginning to reload 357sig round and I'm unsure on how to go about the best crimp for this round. I've read the info on the pete's 357sig page (in the link below) probably 10 times, but I'm not having quite the same results he did.

According to his tests the hard jacketed bullet I'm using should just barely be acceptable and collapse at around 40 lbs of pressure and will actually take much less pressure with most any sort of crimp. In my testing I've found that using the taper crimp that comes in my lee seating die will keep the bullet into about 80-90lbs of pressure before collapsing, but as you can see in the pictures below it leaves a ring around the bullet. Will this affect accuracy and/or safety? Simple reasoning tells me that if a cannelure is acceptable in many bullets than why shouldn't this be?

Other info: The bullet is a 124gr hornady FMJ .355. I am just barely belling the case mouth. Probably only .003". I have a lee FCD as well but I've had two problems with it: I can't get the thing to screw down far enough to make a crimp. I've placed a dime into the top of the die to lower the collet mechanism just to see how the crimps would work (temporary), and the FCD didn't do anything wonderful for setback prevention. Any input is appreciated. Sorry for the crap focus, the phone is getting pretty old.


http://www.handguninfo.com/Archive/www.Pete-357.com/357.safety.reload.htm

 

[rcmodel]

You do not need that much crimp.
Case neck tension is what holds auto pistol bullets in the cases.

The taper-crimp should only straighten out the case mouth bell, nothing more.
It should not crease or mark the bullet.

Even though the .357 SIG is a bottle-neck case, it still headspaces on the case mouth just like all other rimless auto-pistol calibers.

That much crimp can mess up the headspace and even cause high pressure if the taper crimped case gets inside the end of the chamber and has no place to expand and release the bullet.

I believe I'd try for around .376" - .377" case mouth measurement after taper-crimping.

If still in doubt?
Measure some factory loads and make them just like that.

As for Pete?
He says he did a thumb pressure test at 90 lbs.
I say BS to that.

I have measured case neck tension of rifle rounds on a bathroom scale clamped in a woodworkers vice.
70 pounds to slip a bullet in a .223 is a LOT of pressure in a vice, let alone 90 pounds with your thumb!

His bare thumb would require ER attention if he applied 90 pounds of force to a bullet tip with it!

rc

 

[Scimmia]

You do not need that much crimp.
Case neck tension is what holds auto pistol bullets in the cases.

The taper-crimp should only straighten out the case mouth bell, nothing more.
It should not crease or mark the bullet.

Even though the .357 SIG is a bottle-neck case, it still headspaces on the case mouth just like all other rimless auto-pistol calibers.

That much crimp can mess up the headspace and even cause high pressure if the taper crimped case gets inside the end of the chamber and has no place to expand and release the bullet.

rcmodel, I believe you're misinformed about 357 SIG. First, it has so little neck that neck tension often isn't enough to hold the bullet in place. Second, the specs on this round allow it to headspace on both the mouth and the shoulder, with most barrels set to space correctly on the shoulder since people neck down 40 S&W cases which end up too short.

I don't see any problem with that amount of crimp. As long as it's even all the way around and you aren't deforming the jacket in any serious way, you should be just fine.

 

[CaneCorso85]

The crimp in those photos is about .376. I'll ease it back to .377-378. And for what its worth, I agree about the thump thing. I've been using a beretta magazine instead of my thumb. I'd honestly like to see 90lbs on his thumb.

As for factory loads, I've discovered a couple so far that collapse pretty easily so I'm trying to set the standard a little higher. With no crimp at all I can get around 40lbs and I guess that is acceptable for target ammo. Any carry ammo is going to be factory gold dots.

 

[Striker Fired]

I reload quite a bit of Sig rounds,I have been going by 45lbs as a test,but also go by taking several rounds and chambering them in the gun.I try to work the slide as fast and hard as possible to mimic it being fired closely.Then measure setback,then repeat several more times.You should be able to go several camberings with about .01 max setback.None of my bullets are crimped like in those pics, I do put a heavier crimp than normal, but nothing like that. Also if you ever use plated bullets, that crimp will cut the plating and cause multiple problem, few will turn out favorable.

Bullets with cannelures have a groove in the lead core underneith the cannelure so there is still a set thickness of copper jacket underneith,so crimping a groove in the bullet is quite different.

 

[Didereaux]

I set my crimp to...

I reload about 1500 rnds of 357sig a year. I have played with the crimps a lot and found that the best TAPER crimp is when it is set to press in barfely half the thickness of the case neck brass. This leaves almost no indentation on the bullet but still prevents any set back. Others views might differ, but this works for me. The gun I use with it is a SIG P226.

 

[Rodentman]

I feel that the .357 sig is touchy to reload reagarding neck tension. (Obviously)...

I prefer NOT to bell the brass to seat the bullet. I use MT Gold 125g bullets made for this round (not 9mm bullets), I score a cannelure into the bullet and lightly crimp into that with a Lee FCD which isn't the same as their straight wall pistol FCD.

About all the pressure I can get with my thumb is about 45lbs.

 

[CaneCorso85]

What press are you using? I can't get the FCD to screw down far enough to make any sort of crimp on the round. It is the FCD specifically for the 357sig.

Regarding the belling, I think after I'm done with this current lot of 124gr fp fmjs I will be switching to the MT golds or a similar plated bullet. The hornady's have no bevel at the base and therefore I need at least a very small amount of belling to keep from damaging the bullet and/or casing during seating.

 

[Rodentman]

I use a Redding Big Boss II. I haven't reloaded .357 sig in a while so I can't recall how th die sits. I'll take a look first chance I get and see if I can add more info.