Bullet Setback Chart for Factory Ammo: (Test Pistol: Glock 31)

Disclaimer: The following information is what works for me. I am not responsible for your actions. Always refer to factory firearms instructions and precautions, refer to official reloading manuals when reloading, and especially be aware of Local, State, and Federal Firearms Laws. Use your common sense. You are responsible for your own actions!

I performed all of the following tests with the Glock 31 pistol. The only other 357 Sig factory pistol with a 4.5" barrel that I'm aware of is the well made SIG P226.

I tested several brands of 357 Sig Factory ammo to determine how each brand would hold up. I performed a factory bullet setback test, a factory ammo chronographing test, and an "extreme" reloaded bullet setback test using a compressed powder.

Procedure

I performed the factory bullet setback test by measuring the original OAL (Cartridge Over-all Length). I then loaded the round into a magazine and forcefully cycled the slide. I then immediately ejected the round. I then measured the OAL again. I performed this test for a total of 5 slide cycles. The desired outcome of this test was to hopefully show little or no OAL measurement difference between the original and 5^th slide cycle. And yes, I was careful and pointed my pistol in a safe direction while performing these tests. Let's see what happened:

Factory Bullet Setback Chart

Test pistol: Glock 31 (4.5" barrel)

Note: The ammo was rated from top (little or no bullet slippage) to bottom (the most bullet slippage). If there was a tie, then the ammo was listed in alphabetical order.

Note regarding the slight variations of the above measurements:

1. I used a digital caliper. I might have used a slightly different pressure as I closed the caliper to measure (human error). Remember, a 1/1000 - 1/10,000" difference is getting really small for a caliper that's being manipulated by a mere human.

2. Some bullets are more difficult to measure since they might not have a perfectly flat surface because of the JHP design or slightly rounded nose. You take one or two readings and they can vary just a tiny bit, depending on exactly where the caliper is touching the bullet surface.

3. Some softer bullets can measure 1/1000" shorter due to the bullet head compressing slightly from hitting the feed ramp.

4. There's another phenomenon where the OAL can actually get longer after cycling the slide, a kind of reverse bullet setback if you will. I talk about this more at http://www.HandGunInfo.com/Archive/www.Pete-357.com/357.safety.reload.htm

Basically, I just wrote down the measurements as they showed up.

Factory Bullet Setback Chart Results

See below for the chronograph velocities of these factory brands.

Bold lines in the above chart represent ammo that passed the bullet setback test with a high rating. I strongly recommend using this level of ammo if you are in law enforcement and/or carry for self-defense, since it can handle multiple reloads into the chamber without significant setback. My reload data was listed in the bold section to demonstrate that it's possible to reload 357 Sig ammo safely without bullet setback problems.

Most of the other brands did OK. They could be cycled two or three times with little change in the OAL. This level is probably fine In My Humble Opinion for practice ammo that will be fired usually within one or two slide cycles.

The RBCD ammo actually had reverse bullet setback where the bullet extended out of the case a little bit more after each slide cycle. The OAL seemed to stop lengthening at roughly 1.142. Watch out that the OAL doesn't get too long to properly feed in the magazine and that the bullet does not actually pop out into the barrel as it's fed into the chamber. This ammo appears to be a compressed load.

The CCI Blazer ammo suffered a significant bullet setback with the very first slide cycle. I would not recommend cycling this brand more than once. This lot number of Blazer ammo should be used with caution. Hopefully, newer lot numbers will improve.

On the other hand, the Blazer ammo performed excellently. I even test fired the very short Blazer cartridge with the above OAL of only 1.088 using my Glock 31. I do not of course recommend anyone else doing such a crazy thing. There were no over-pressure signs and it fired fine. It appears that the powder used in the Blazer ammo "might not" be overly sensitive to high pressures from a certain amount of bullet setback. If I didn't reload, I would use Blazer sometimes.

How far can the bullet set back into the cartridge before you have a serious over-pressure problem? That depends on the powder burn rate, etc. Ask the ammo company what the minimum safe OAL is for their ammo.

Well, as you can see, it's a good idea to do a simple check on a round or two when you buy a new box of factory ammo. In fact, I would recommend checking regardless of caliber type. Optionally, you can press the bullet end of the ammo against a bathroom scale to see if it can handle around 45 lbs of pressure, which more or less simulates the bullet hitting the feed ramp. You may be surprised. Just because it comes from a factory does not mean it's infallible.

Factory Bullet Setback Chart Summary

Several factory brands worked excellently. My reloads worked excellently even though I used old brass that had already been used several times. Several other factory brands held their own pretty well for two or three slide cycles, which should be fine for practice ammo. Blazer has some bullet seating improvements that it could make. I wish I had more brands to add to this chart. I have heard really good things about the police only version of the Winchester Ranger ammo.

Is the 357 Sig caliber safe to use? Yes, if it is loaded correctly!!! Please remember that in the U.S. this is the first popular bottlenecked pistol cartridge in almost a century. This caliber has only been out since 1994. Therefore, the ammo companies and reloaders simply have to get up to speed so all 357 Sig ammo is loaded correctly!

If your gun can handle it, then ease the slide forward, so that the round is very gently pushed into the chamber. Then give the rear of the slide a rap, to be sure everything is locked up. This method is used by some Glockers I know and it definitely cuts way down on bullet setback issues.

I am just trying to share some information with everyone so we can be safe. If you have corrections and or info you would like to share, then please contact me.

If anyone wants me to check out a brand not in my chart yet, please email me and let me know how I can get hold of it, within reason. I spent over $150 just for my first 9 factory loads in order to create these initial charts!

For quite awhile, I have believed the bullet diameter range for the .357 SIG to be .355 to .356. You can get a 9mm .355 bullet to work in a 357 SIG case if it is shaped correctly and the correct bullet crimp is used for the type of bullet being used. After doing my own limited testing, I now believe the 357 SIG ideally should use a bullet diameter between .3555 to .356, and not the standard size .355 bullet, if possible. The correct bullet size and shape is a critical step to minimizing bullet setback. A main reason West Coast Bullets and Rainier Bullets work excellently in the 357 SIG caliber is because they happen to measure .3555. The SAAMI maximum for the 357 SIG bullet diameter is .3555.

I pulled the following picture from the XD/HS2000 talk forum, http://www.hs2000talk.com  which shows three stages of bullet setback with factory UMC 180 grain .40 ammo. The cartridge on the right was cycled through the slide and ejected several times. The middle cartridge was cycled less times, but after another dozen or so cycles, it looked about the same as the right most cartridge. The left cartridge has not been cycled at all. Like I said, it ain’t just 357 Sig ammo you have to worry about. This can happen to any of the duty calibers. Folks, be careful.

Factory Velocity Chart: Highest Average Velocity to Lowest

Test Pistol: Glock 31 (4.5" barrel)

How strong is the 357 Sig Cartridge?

The 357 Sig case is made to handle high pressures. I know of one professional who has tested 357 Sig ammo with pressures over 45,000 psi and there were no signs of over-pressure. Let me add quickly, that I highly recommend staying below the maximum average SAAMI pressure of 40,000 psi.

In fact, some folks have suggested that over time the 357 Sig will be downloaded. I disagree because it has already been downloaded. The brass is strong enough and has been tested at 45,000 psi as already mentioned without showing any pressure signs of any kind. But SAAMI is using a conservative maximum average pressure of only 40,000. Depending on the factory ammo, 357 Sig ammo can actually have pressures as low as 33,000 psi, such as Blazer, because of the strength limitation of their throw away cases.

To show you how strong the 357 Sig cartridge really is, as well as how sturdy the Glock 31 is, I test fired a series of cartridges that I "purposely" made with major bullet setback (see charts below).

In the following bullet setback loads, AA#9 was literally compressed and holding up the bullet so it could not slip into the case any farther. Once again, do not try this at home kids:

Extreme Bullet Setback Chart Using AA#9 Powder

Test pistol: Glock 31 (4.5" barrel")

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

(Brass diameter expanded to a maximum of 0.428") 

Extreme Bullet Setback 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.

Accurate Arms has stated in their most recent reloading manual that the 357 Sig cartridge is without a doubt the most ballistically efficient pistol caliber they have ever tested. Their reloading manual lists compressed AA#9 loads as well. Please refer to my AA#9 article for more details: http://www.HandGunInfo.com/Archive/www.Pete-357.com/rel.357.no9.htm

Extreme Bullet Setback Summary

Three important points 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.

Glock 31 Test Summary

For all practical purposes, I consider the Glock 357's to have a fully supported chamber (or at least a well supported chamber for those literal types out there). That's because in the 6 o'clock chamber opening, very little brass is showing and that's only the thick reinforced part of the 357 Sig case. And furthermore, the Glock 357 chamber is fairly tight. Even with full power loads, the maximum brass diameter expanded to only 0.428.

With a steel guide rod and a 20 pound recoil spring for a full size Glock or 20 - 22 pound for a compact size Glock), the felt recoil of a Glock 357 is tamed and feels just as mellow to shoot as the excellent SIG P229 pistol. It takes a little bit more muscle to rack the slide, but it’s worth it.

Another plus for the Glock is its simplicity. It has fewer parts than most other pistols and is very easy to work on. Glock armorers are in abundant supply and it's very easy to find Glock parts and purchase aftermarket barrels, etc.

The original Glock pistol was engineered to shoot 9mm ammo. The new Glock 357 pistol also shoots a 9mm bullet. This is probably another reason why the Glock 9mm and 357 pistols have well supported chambers. The bottlenecked 357 Sig also has an added advantage of easily ramming a 9mm bullet into a 10mm chamber opening, as long as the pistol and magazine are operating within acceptable parameters. With the larger calibers, Glock made the chamber a little looser with a bit more exposed brass in the 6 o'clock position of the chamber opening. I'm not saying this is good or bad. I'm just saying that's the way it is. However, I do have to admit that I've always been concerned about the unsupported chambers of the larger caliber Glock pistols, and have therefore been a fan of high quality after market barrels.

The Glock 357 series is quite flexible as well. From the factory and/or from third party sources, I can fire four different calibers in my Glock 31: 357 Sig, .40, 9mm, & .22. Glock triggers range from 3.5 pounds to over 10 lbs. There's even an aftermarket manual safety that can be installed for those that feel the need, although, I'd like to find out more about it before posting any detailed information here -- http://www.cominolli.com/glocksafety.htm Of course, a manual safety is simply a toggle switch and cannot take the place of a true security lock. A much better unobtrusive method would be to buy Glock's new fully integrated cylindrical locking system with unique keys.

The Glock 31 fired all of the factory brands flawlessly and easily handled all of the "extreme" AA#9 bullet setback reloads in the charts listed above. I'm very impressed with the Glock 357 series. Just to make it more exciting, I even used old brass that had been used several times before. And I used this old brass even for the maximum, full power loads shown in the above chart. This test is for example only and not meant for you to copy. Normally, you should use new brass for full power loads.

I also found the Glock 31 to be accurate just like the excellent SIG P229 and sigpro P2340 pistols. I really find it difficult to complain when my combat Glock pistol turns in 1.5" to 2.5" accuracy right out of the box, with a cost of only $500, and is extremely durable and easy to use as well.

"The National Institute of Justice (NIJ), through its Office of Law Enforcement Standards (OLES), has developed voluntary minimum performance standards for revolvers, autoloading pistols, and shotguns for police use" --- Reports from the NIJ can be found at http://www.nlectc.org/testing/pistols.html  The Jan. 2000 report showed two Glock 31 pistols pass the suite of tests with a perfect score. In that same report, some other well known pistols did not score so well.

You would be hard pressed to travel anywhere in the world without running into Glock pistols. Several countries use Glocks. Over 65% of the U.S. police agencies use Glocks. Why? Because it's a proven design that is reliable, easy to operate under stress, and simple to maintain with less parts than other competing pistol brands.

Like any pistol style, you must still train to operate even a Glock safely. You "never" put your finger on the trigger until you are actually going to fire. Use a holster and make sure the thumb strap, your finger, etc is out of the way during reholstering. Very simple. Very effective. Do not use TV or Hollywood movies as your training guide! Actors in general break so many safety rules it's horrifying!

When I hear about the occasional Glock blowing up or someone experiencing an accidental discharge, I need to hear the complete story. Was the pistol analyzed after the accident? Was the pistol being maintained properly before the accident? Was the factory ammo lot number checked? Was the reloaded ammo checked? Were one or more of the four cartridge components defective? Did the owner follow the simple safety rules? Can the owner even recite the simple safety rules? What did the ammo company say? What did Glock say? You rarely seem to hear the whole story!

The bottom line is that there are a heck of a lot of Glocks out there with millions of rounds pouring through them. And yes, some Glocks have blown (we all agree on that), just as have several other well known brands. Yet, with all this finger pointing, NO "person" or "company" has ever been able to undeniably prove that there is an engineering defect in the current Glock design. Why is that? Why is it that I could perform the above mentioned extreme, abusive tests without having any problems whatsoever with my Glock 31? :)

If you visit www.ammolab.com (be sure to read their main page and copyright info), you'll see some excellent testing reports of the 357 Sig and others. One chart shows the results of an overcharged 147 grain bullet fired from a Glock 32 (4" barrel). The Glock held together fine although the recoil and blast were quite severe. The bullet was clocked over 1800 fps, rupturing the case. Folks, this was over 600 fps faster than a typical maximum 147 grain load is capable of. It penetrated 18.5" and the bullet was an exploded fragment of only 34.7 grains. Obviously this round was far, far beyond the 40,000 psi maximum, yet the Glock 32 was unscathed. I believe this is yet another example of how tough Glocks really are.

Now, if you have a Glock made before 1993, then you definitely need to get it upgraded to take care of some issues; Give Glock Inc. or glockmeister.com your pistol serial number to find out what year it was made. Visit "The Gun Zone" for an interesting upgrade history as well as Glock kB pictures: http://communities.prodigy.net/sportsrec/gz-directory.html (Show me ALL the facts and I will gladly listen.)

All pistol styles need to be handled safely. For example, a single action 1911 pistol needs to have the manual thumb safety flipped on and off in order to use the pistol safely. A SIG has to be manually decocked in order to safely holster it, etc. Follow the General Safety Rules and then your pistol should not "go off" with these negligent, accidental discharges: General Safety Rules