Bullet Setback Test using AA #9 Powder

[petej88]

Addendum: Well, #9 appears to give a nice wide range of 357 SIG velocities from 1082 - 1468 fps, from a 4" barrel. And it appears to uniquely handle bullet setback well. I decided to do one more test of bullet setback by changing the bullet type and the brand of 357 SIG cases....
Component Combination Test

The combination of components can make all the difference in the world. And changing just one component can make a huge difference. As an example I decided to do a bullet setback test using six different brands of 357 SIG brass. I also tested the difference between a Rainier 124 grain flat point bullet and a West Coast 124 grain flat point bullet using Starline brass. Just to make it interesting, I then took the chrono statistics after shooting one of each of these rounds:

#9 Charge Weight: 12.1

(Case Brand) (Bullet Setback OAL) Velocity Bullet

FC (1.079, 1.082 *L) 1214 Rainier
Hornady (1.059, 1.059 *L) 1171 Rainier
RP (1.075, 1.076 *L) 1180 Rainier
Starline (1.097, 1.099) 1201 Rainier
Starline (1.095, 1.096) 1197 West Coast
Speer (1.072, 1.082 *L) 1186 Rainier
Winchester (1.096, 1.095) 1193 Rainier

*L refers to the fact that the normal part of the bullet that is crimped is "Low" and inside the case, although most of the cone shaped bullet is still outside the case! How many of you would fire such a bullet? Hopefully, none!

Bullet setback chart stats, from the above multi brand cases:

Grains High Low (Extr. Sprd.) Avg. (Std. Dev.)

12.1 1214 1171 43 1191 14


I then fired two groups of normal loads, using 11.9 and 12.1 grains with a maximum OAL of 1.140, for comparison:

Grains High Low (Extr. Sprd.) Avg. (Std. Dev.)

11.9 1137 1122 15 1131 5
12.1 1181 1125 56 1156 23


Results:

Notice the wide difference in the OAL's of the various brass brands. This could make a huge difference, especially if using faster burning powders. Notice there is only a 4 fps difference between the Rainier and the West Coast bullets, and the OAL's are almost identical as well.

I did notice that some of the unburnt AA#9 powder did end up on my chronograph ten feet away. At first, I thought it was just a little dust. So, even if you miss the bad guy, you can temporarily blind him by throwing powder in his face.

Since I normally use a cannelure grooved bullet and a strong roll crimp, I am more than satisfied that this process alone is sufficient and safe to shoot 357 SIG reloads. The above test with #9 is just a secondary insurance measure, which might be of use.

Then again, there will be some folks who prefer a powder that uses less grains per load in order to save money For example, a maximum charge of 5.8 grains of Universal produces a clean burning, mellow 9mm like recoil (average of 1118 fps and a power factor of 138). Compare that with an almost equivalent recoil produced by 11.9 grains of #9 (oal 1.140; average 1131 fps; power factor: 140). You decide.

Note: I have only tested a few bullets that work well with a cannelure groove and/or a strong roll crimp: Rainier 124 fp, West Coast 124 fp, Oregon Trail Laser-Cast 122 fp, and the Speer 125 Gold Dot HP. Hard plated and hard jacketed bullets require a light crimp, otherwise the case can be damaged/wrinkled. And basically very little or no bell can be used, in order to hold the bullet in place better. Yet from my experience, the hard bullets still do not hold as well as the softer plated bullets, especially when reusing fired brass.

I use a Dillon 550. When I say, "no or very little bell", I mean this: On the powder bar is a little square piece of white plastic. When initially setting up your powder drop system, in order for the powder to drop consistently, this white square most travel the entire length and touch the far wall. When you have the powder die adjusted so this happens, then tighten the die down. This is basically the tightest that you can make it. If you measure the case mouth, it will probably measure aprox. .375 - .376. Since the Rainier and West Coast bullets have a beveled bottom, they are still easy to seat into the case. After seating the bullet, the mouth will expand to around .379.

I never thought I'd be saying this. But I feel that I can reload the 357 SIG caliber "without" a cannelure groove when I'm using Accurate Arms #9 powder, because of the bullet setback security. Now, that does not mean I'm going to get sloppy and not be concerned about holding the bullet securely in the neck. This is simply what works for me. I make no guarantees whatsoever of how it will work for you. But I am glad to share this knowledge with you. Take care and be safe.

A complete detailed html version of all this testing is at my web site:

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My Site: http://home.earthlink.net/~petej55