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I've been doing some crimp testing and wanted to share my results so far.
Different ways people are crimping the 357 SIG today:
1. The successful reloaders appear to bell the case mouth very little if any, so they can just barely squeeze the bullet into the case in the seating stage. Some don't bell at all and use a beveled bullet, or even ream out the case mouth a tad bit so the bullet can get started into the case. Then they use a tight crimp. This generally seems to work OK.
The tricky part is that various brands of brass are slightly different. So my die might be set perfect for Starline brass but expand the case mouth a hair too much on Hornady brass. So mixing brass can be a little dangerous in this regard (as in bullet setback).
2. More ammo companies appear to be using a glue to hold the bullet in place. This makes bullet set back almost impossible and safer to use for those that have to unload they're mags and reload them with the same ammo. I haven't heard of any ammo companies creating a special crimp yet for the 357 SIG.
3. The newest technique which appears to be just as good as glue, or better, is:
Putting a light cannelure groove on the bullet and using a "mild" RCBS roll crimp. This allows the outer edge of the case mouth to be twanged with a thumb nail and to head space corectly on the case mouth. Instead of a mild RCBS roll crimp (which I believe is the best), a "strong" taper crimp with a Lee crimp die also seems to work fairly well.
I did a thumb pressure test on a weighing scale with a cartridge (cannelured and RCBS crimped). I went up to 75 lbs of force before my thumb gave out! ZERO SLIPPAGE!! And this method is perfectly consistent. You can even mix brass and it all works fine, once you get the die settings down right.
Caliper measurements: If I measure the diameter of the 357 Sig neck (about half way down the neck, it measures a firm .377 - .378. If I measure the absolute top of the neck at the crimp point, it measures a little tighter. If I pull the bullet out of the case, there is a little crimp ring on the bullet, but it is not deformed.
I'm out of town until the 20th. When I get back, I plan on setting up some new chronograph tests with some cannelured, rcbs roll crimped rounds, using Power Pistol, Blue Dot, and AA#9. I'll let you know what the results are. I'm expecting some amazing standard deviation numbers and some higher velocities.
Some of you might be groaning that you don't want to add yet another step of canneluring your bullets with the excellent Corbin Cannelure tool. BUT, I'm sure we could talk West Coast Bullets or someone into doing that for us. After all, a good high speed cannelure machine can crank out over 100 per minute (set for an OAL of 1.135). The bullet companies just need the customer demand to do it.
After playing with the 357 Sig for over four years, I'm feeling really good now.
Dies that seem to be giving some people problems:
I've heard multiple complaints that the RCBS resizer die screws up the shoulder position and then there are feeding problems. Although, I really love their roll crimp die.
I stopped using the Dillon crimp die because it would not let me make a firm crimp without the bullet slipping.
Hopefully, these problems will be taken care of eventually. Any other problems from various dies?
By the way, does anyone know of any good "bulk" 147 grain bullets that would work well (short nose)?
See you this Thursday, unless this message is already obsoleted from disinterest <G>
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