Accurate Arms #9 Setback Tests

Disclaimer: All of the following powder charges were taken from reloading manuals produced by gun powder companies or other reloading manuals that may vary in powder charges greatly. Various components combined, make all the difference in the world. I am not responsible for your actions. Always refer to official reloading manuals when reloading. As usual, I must say that this information is what works for me. Use your own common sense. You are responsible for your own actions!

AA #9 may be the most forgiving & versatile 357 Sig powder on the market.

Accurate Arms Company 800-416-3006; www.accuratepowder.com

Bullet Setback Data for 147 Grain Bullets

Springfield XD  with standard 4.0" barrel

Starline brass

Winchester primers

Rainier 147 grain plated hollow point bullet

WARNING: The following bullet setback chart is meant for example only and I do not recommend trying to duplicate this test. Even though it worked for me, it may not work for you. You are responsible for your own actions.

Bullet setback test means that I literally crammed the bullet as far into the case as possible so the #9 powder was actually holding the bullet up. This is a crude test to show that #9 works well under compression and appears to provide some bullet setback insurance for those that may be concerned. You can think of this test as provoking a worse case scenario. The good news is that #9 performed admirably and no apparent overpressure signs occurred. Kids, do not try this at home/on the range. I did not actually test the pressures generated in this exercise. I merely observed the firing sequence and the results after the fact.

*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 nose is still outside the case!

**Regarding Maximum Diameter Expansion of Case: For this test, I used once fired brass so it was easier to push the bullet into the case. The brass diameter measured approximately .424 before firing it. The low diameter case measurements really shows off the excellently supported XD chamber opening and fairly tight chamber in general. In fact, the XD 357 chamber is the best I’ve ever seen in a 357 Sig based pistol.

Bullet Setback Data for 124/5 Grain Bullets

The Bullet setback data in this section is NOT meant to be duplicated by you. You are expected to use common sense when reloading. The following information is for reference only!

I decided to test AA #9 since the manufacturer, Accurate Arms, has stated that their slowest handgun powder can work with compressed loadings, based on their book, "Accurate Smokeless Powders Loading Guide: Number Two".

There is an interesting peculiarity with the OAL and compressed powder charges. When you add 14.0 grains of #9, my Dillon seater die can help to compress the powder as the bullet is inserted. Therefore, you need to take this into consideration when using a compressed powder. Obviously, you do not want to over do it with extreme compression. Be safe.

Another quirk with some compressed loads, is that the powder can push the bullets back out to a degree, causing a reverse bullet setback. I've heard of this phenomenon from rifle shooters. I'd recommend using a caliper to make sure the OAL is what you are expecting.

In order to simulate the bullet setback, I had to bell the case a bit, no cannelure was used, and of course no crimp at all. I also used old brass since bullet slippage is easier when the brass is not new. I then used a Dillon flat wrench to help me push the bullet into the case, using a cement floor for leverage. Don't try this at home, folks!

I repeat that compressed #9 powder was virtually the only thing holding the bullet in place to simulate a bullet setback!

Steyr M357 pistol with a standard rifled 4" barrel.

Starline brass.

Standard Winchester pistol primers.

Rainier plated 124 grain flat point bullet (.5275" length +/-.002", which is somewhat similar to the West Coast 124 grain flat point bullet).

As you look at the following bullet setback OAL's, be aware that the 357 Sig caliber normally has an OAL between 1.120 (min) and 1.140 (max), based on various reloading manuals..

Chart 1

Chart 1b

Test pistol: Glock 31 (4.5" barrel")

Starline brass; Winchester primers; West Coast 124 grain full plated bullets

Chart Results:

There were no over-pressure signs with the brass, the Glock 31, or during the firing sequence. I did not measure the actual generated pressures. As you can see, the OAL's got radically short.

In summary, three important things are obvious. First, AA#9 powder appears to function well even in a compressed state (holding the bullet up) without destructive over-pressure. Second, the 357 Glock 31 is a mighty tough and reliable pistol in order to handle this kind of abuse. And thirdly, if the right 357 Sig components are picked, the 357 Sig caliber is just as safe or possibly even safer than other duty calibers.

The following chart compares the effects of 11.9 grains of #9 in the bullet setback position, with an OAL of 1.123, and with an OAL of 1.138. This was a interesting test since all three tests were created at the same time to assure the charge weight was the same. The only major difference is the OAL. And all three of these tests were fired in the same session to cut down on variances.

Rainier bullet

Chart 2

Note: Chart 2 was fired on a separate day than Chart 1. So due to weather variations and plus or minus 1/10 gr. accuracy on my powder measure, the velocities were higher. In fact, the 11.9 (+/- 0.1) load in Chart 2 was somewhat equivalent to the 12.2 (+/- 0.1) load in Chart 1. So theoretically, the charge difference between these two loads might have been within 0.1 grain of each other. Hey, I just record the results J

Results From Charts 1 & 2

In all the above tests, the brass looked normal and caliper brass measurements were virtually the same between the normal and bullet setback loadings. Perceived recoil between the various OAL's within each charge group appeared to be similar. In fact, I was amazed at the mild perceived recoil even with a maximum 14.0 grains of #9.

I did not have equipment to measure the actual pressures of each cartridge!

What's interesting is that the velocities between the various OAL's of each charge group of the fully setback loads, are all in the same ballpark as the normal OAL charts from 14.0 down to 11.8. Although, the 11.8 and 12.1 bullet setback groups have a higher 50 fps velocity. Beginning at 12.4 up to 14.0, the bullet setback velocity differences with the normal OAL charts is minimal.

For Chart 3, I did a full suite of testing with a different brand bullet. This time I used the excellent D&J 124 grain full metal jacketed bullet, which has a length of .553" -- .025" longer than the Rainer bullet. Most of the extra length comes from the longer nose.

D&J full metal jacketed 124 grain flat point bullets -- .553" length

Chart 3

*11.8 grains of #9 is the minimum charge possible to hold the D*&J 124 grain flat point bullet up enough in a Starline case so a crimp can be applied in the correct position, just barely shy of the cone shaped nose.

Results from Chart 3

The velocities have a continuous progression from 11.8 up to 14.0. You will also notice that the OAL's are approximately .02" longer at each charge weight because of the difference in the D&J bullet length.

Some of you might be aware that there is reloading data for 1911 style shooters that can successfully use "long" .40S&W OAL's. This ability can give good velocity and lower pressures under certain circumstances. I mention this since you will notice that beginning at 13.4 and greater, the SAAMI 1.140" OAL max was exceeded and got as high as 1.156"! Well, it so happens that my Steyr M357 pistol can indeed handle "long" 357 Sig cartridges in the chamber as well as in the magazine. Be very careful about this when you are reloading your particular brand X bullet.

In fact, beginning at 13.4 grains up through 14.0 grains, there was a noticeable flattening of the primers, although the primer dent still looked good and no primers were blown out of the pocket. Since the D&J bullet is longer than the Rainier bullet, the powder compression from the seater die began getting intense. The powder was packed solid and still the OAL went way over the SAAMI max. Therefore, this was a good experiment to show how changing just one component and working at higher charges could prove to be quite dangerous. In fact this is a great example showing that the max charge of 13.0 in the AA Reloading Manual is correct for this bullet, and the Speer max of 14.6 is not. To be fair to Speer, that's why their reloading book tells you exactly which bullets they used for testing!

At the light to medium loads, the D&J bullet performed very well.

For Chart 4 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:

Rainier & West Coast bullets

#9 Charge Weight: 12.1

Chart 4

*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 nose is still outside the case! The slightly varying multi brand case lengths also had an effect regarding the crimp point. How many of you would fire such a bullet? Hopefully, none! J

Results From Chart 4

(Rainier bullet)

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. There is a 35 fps difference between the bullet setback cartridges and normal, maximum length cartridges. I'm amazed at the small velocity difference even though there are massive OAL differences that range from 1.059 to 1.140. That's an OAL difference of over 0.08 (almost 1/10")!!! Remember, the "normal" OAL range is between (1.120 to 1.140) based on reloading manuals.

For Chart 5, I performed another 6 brand 357 Sig case suite, this time using:

D&J 124 grain FMJ flat point bullet:

#9 Charge Weight: 11.8

Chart 7

*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 nose is still outside the case! The slightly varying multi brand case lengths also had an effect regarding the crimp point. 

For Chart 6, I fired two groups of normal loads, using 11.8 grains of #9 with an OAL of 1.130 and 1.140, for a comparison with the above chart:

D&J bullet

Chart 8

Results of Charts 5, & 6

(D&J bullet)

Once again, there is a wide difference in the OAL's of the various brass brands. Yet, the velocity difference between the bullet setback cartridges and the normal length cartridges are all within only 23 fps of each other. This time the OAL's ranged from a minimum of 1.075 to 1.140 (excluding the OAL's longer than the SAAMI max). That's a difference of 0.065, almost 1/10" again.

In Summary

I repeat, Accurate Arm's slowest burning handgun powder #9 may be the most forgiving & versatile 357 Sig powder on the market. AA #9 appears to be a very stable powder for the 357 Sig caliber. Therefore, #9 appears to not only power the bullets sufficiently, but also has a dual purpose of helping to hold the bullet in place if bullet setback should occur.

I would not even consider doing the bullet setback testing with faster burning powders than AA #9!!! I'll let the ammo labs do that.

I normally reload 357 Sig two different ways. In fact, I have two sets of dies always ready for action. For soft copper plated bullets, I use a cannelure groove and a strong roll crimp. This works marvelously for bullets such as the Rainer 124 flat point, the West Coast 124 flat point, and the Speer 125 Gold Dot HP. The Oregon Trail 122 grain hard lead flat point works well with a strong crimp. On the other hand, for hard full metal jacketed bullets such as the above mentioned D&J bullet, I use little or no case belling expansion, and little or no crimp. An overcrimp on a hard bullet can cause the case to get wrinkled/damaged, or actually loosen the bullet so that it might slip into the case. Please read my 357 Sig Safety & Reloading article for more details.

Well, I brought up my methods for reloading, because we now have another level of insurance besides a cannelure groove and strong crimp with those bullets that are compatible with this process. Accurate Arms #9 powder appears to provide bullet setback security. In fact, a cannelure groove may not be necessary when you use AA #9, although you would be bypassing that extra security.

I'm glad to share the above findings with you. But please be very careful and follow standard reloading practices. The above bullet setback charts are not meant to be emulated. They represent emergency bullet setback scenarios. Take care and be safe.