What is bullet setback and is it dangerous?


PDA






Potatohead
April 30, 2013, 03:46 PM
I've been noticing these two words lately (bullet setback) and am just wondering a bit about it.I think i read that it can happen if you keep chambering the same round over and over..? I dont normally keep my gun locked and loaded all day everyday but I'm in the produce business which is an up-real-early in the morning kind of job so i pretty much chamber a round upon leaving for work, and then later in the day i usually unload it and put it back into the clip/magazine. Or i will have to go in at 9 or 10 pm to unload a truck, so i'll chamber one for that and then unload the gun when i get home. I know i could just keep it loaded but i have a 2yr,4yr, and 12yr old at home so i like to keep it unloaded at home,throughout the day... do i need to chill with all the loading/unloading? or what does cause this? What happens if you fire this round? Is it dangerous? Can i look and see that the bullet is actually "set back" etc etc etc Sorry for the long post

If you enjoyed reading about "What is bullet setback and is it dangerous?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
Potatohead
April 30, 2013, 03:49 PM
EDIT: i think title should have been "what is bullet setback and HOW dangerous is it"...im sure its gota be somewhat dangerous

CoRoMo
April 30, 2013, 03:51 PM
The level of danger is going to be different from one cartridge to another.

Bullet setback in a high-pressure rifle cartridge is going to get dangerous MUCH quicker than setback in a .45acp round. Of course, many rifle cartridges can barely be over-charged because a compressed charge will take up every bit of room behind that bullet.

Fryerpower
April 30, 2013, 03:55 PM
http://www.thehighroad.org/showthread.php?t=692606&highlight=setback

See post number 8 for a great photo showing setback progression.

Jim

WardenWolf
April 30, 2013, 04:31 PM
Bullet setback is where a bullet is pushed backwards into the casing due to repeat chambering or a misfeed. As for how dangerous it is, that depends on how bad the setback is, the characteristics of the individual round, and the gun it's fired in.

The perfect storm is often considered to be any Glock in .40 S&W. The .40 caliber cartridge is unusually prone to setback, and as little as 1/10 of an inch will double the pressure inside the case. Even worse, older Glocks had a poorly supported case, that was significantly worse than other manufacturers' firearms; this made them more prone to case rupture. As a result, almost every single time you'll hear of a pistol going kaboom, the culprit will be a Glock .40.

I DO consider that pistol and round combination to be dangerous, and DO consider the .40 S&W round to be flawed. That is one caliber I resolve never to buy.

holdencm9
April 30, 2013, 04:43 PM
colonel kernel,

It can be dangerous, and it is due to chambering a round multiple times. How dangerous, and how many chamberings it takes to become dangerous, depends on many factors

1. The cartridge. Higher pressure cartridges have less room (case volume) to play with. 9mm Luger is relatively high pressure, as is .40S&W. As such, a small amount of setback can quickly become a problem, causing pressures to spike.
2. The brass. Some brass is a hair smaller and holds the bullet tighter, so setback won't occur as easily. This can sometimes be a lot by manufacturer, with the same cartridge.
3. The gun. Some designs chamber smoother than others. The Kahr design for instance, seems to have a very steep feed ramp, so the nose of the bullet is bashing into it every time you chamber a round, and bullet setback will occur faster in such guns.

Basically, if it is a visible setback, it probably isn't safe to fire. To minimize setback, avoid chambering a round every day. If you absolutely must continually chamber and eject rounds, try to rotate the rounds that get chambered, rather than chamber the same one over and over and over.

Drail
April 30, 2013, 04:56 PM
Chamber a round only one time into a semi auto. If you absolutely have to unload and reload every day buy a revolver. Do not rechamber factory carridges more than once. If you want to learn to handload then you can easily build a cartridge that will not set back. I will be glad to tell you how. With factory ammo you're playing Russian roulette if you rechamber it. They do not make any guarantees that their ammo will not setback (or even fire one time).

SouthernBoy
April 30, 2013, 05:01 PM
For those who practice trigger discipline on a regular basis with their carry guns, which is a wise move to do, and they carry with a round in the chamber, bullet setback is a very real concern with semi-autos. There are a few pistols which are fine for "riding the slide", but do make sure your pistol will handle this method of chambering a round correctly and that the manufacturer does not recommend against this method.

The Glock design is one of the pistols which will support riding the slide due to two primary reasons. 1) The top cartridge in the seated magazine sits high in gun so the path to the barrel's chamber is more straight, i.e., there is less of an angle and therefore less action with the feed ramp. 2) The extractor comes up under and between the rim and case instead of moving over the rim. By riding the slide with the Glock after performing your trigger discipline, your chambered round has a far less chance to set more deeply in the case.

CAUTION: If you do this, be sure to carefully inspect the round you intend to chamber against a fresh round to make sure there is no setback.

I have been doing this for years and have never had any problems. As the round is picked up by the slide and moved into the chamber, there is very little pressure on the bullet's nose. Check this out for yourselves if you carry a Glock.

Manco
April 30, 2013, 05:40 PM
I DO consider that pistol and round combination to be dangerous, and DO consider the .40 S&W round to be flawed. That is one caliber I resolve never to buy.

It's not just about caliber, though. For instance, a .40 S&W PDX1/Ranger-T is far LESS likely to suffer from bullet setback than a 9mm Gold Dot; you could chamber a round of the former over and over until you're sore with no measurable setback, while the latter may have some visible setback after just a few chamberings.

Darkbob
April 30, 2013, 06:03 PM
The reason that bullet setback causes the higher pressure is because when the bullet is seated deeper into the case, the available case volume is reduced. Lower volume than expected with the allotted charge gets you higher pressure.

If you put a round that's been chambered a few times side by side with one that has not been and can visibly see that there is a difference in OAL (over all length), then you should be wary of the shorter ones because they will have a higher pressure. In the pic from the link above, I'd never consider shooting the rounds set back like most of those in the picture.

I do rechamber my carry rounds regularly, so I do pay attention and rotate them regularly.

Jim, West PA
April 30, 2013, 06:04 PM
This question is best suited for the reloading forum.

Potatohead
April 30, 2013, 07:02 PM
Thx guys very good info as usual

Potatohead
April 30, 2013, 07:08 PM
Drail, i do plan on reloading sometime in the future. Thx

Also i hate to hear that about the .40rd, i was thinkin of goin that direction on my next purchase

LJ-MosinFreak-Buck
April 30, 2013, 07:43 PM
Get a lock-box and leave the pistol chambered. I've rechambered the round in my G22 numerous times without perceptible set-back.


~On The Road Again...~

beatledog7
April 30, 2013, 09:00 PM
This question is best suited for the reloading forum.

No, because factory ammo can suffer from this condition as well.

Potatohead
April 30, 2013, 09:05 PM
fryerpower, nice pics thanks...it seems like some setback could be hard to notice. were all of the bullets to the right of the first setback? yikes. hopefully its not as dangerous if their is just a bit of setback? or can a little be a lot?

Potatohead
April 30, 2013, 09:07 PM
southern boy, could you elaborate on "riding the slide"? im a bit green. im pretty sure i know what riding the slide is, but what exactly were you meaning about it?

Potatohead
April 30, 2013, 09:10 PM
oh oh oh i gotcha now...how do i know if its ok to "ride" on my particular gum (sr9)? manual didnt say anything against it that i remember, and also how do i tell if the bullet has an easy path to the chamber, just look? all guns look the same down there to me in a way

Potatohead
April 30, 2013, 09:13 PM
.40 S&W PDX1/Ranger-T is far LESS likely to suffer from bullet setback

why? its a shorter cartridge or something? and why would a .40 be less likely than a .45 to setback? keep in mind im not very familiar with many of these rounds

steve4102
April 30, 2013, 10:27 PM
Here is an interesting read on Bullet Setback. Note the extreme setback and the results when fired.

https://plus.google.com/+luckygunner/posts/CiVxdHvWjYS

SouthernBoy
May 1, 2013, 05:32 AM
Deleted due to duplicated post.

SouthernBoy
May 1, 2013, 05:40 AM
Posted by: colonel kernel
southern boy, could you elaborate on "riding the slide"? im a bit green. im pretty sure i know what riding the slide is, but what exactly were you meaning about it?

Sure. Riding the slide is a term that means you hold the slide as you let it move into its battery position (fully forward and locked) from its locked open position instead of letting it go forward on its own. You don't do this slowly but rather in a smooth and constant motion forward. Your hand is "riding the slide". Most semi-automatic pistols do not lend themselves to this practice and those that do not usually can be determined by the resistance they present when doing this. One company specifically informs the owner how the slide is to be put into battery (Kahr) and that is through the use of the slide stop.

The Glock design handles this just fine, causing no undue action to the extractor (it doesn't even move as the cartridge is forced into the chamber, or any other components. And no bullet setback, though once again I caution that if someone does this, they should carefully check their round to be re-chambered before chambering it again.

Gadawg88
May 1, 2013, 10:35 AM
Keep it loaded and get one of these to keep it out of unintended hands while home: http://www.amazon.com/Gunvault-MV500-STD-Microvault-Pistol-Safe/dp/B000TG9RCC/ref=sr_1_1?ie=UTF8&qid=1367418565&sr=8-1&keywords=Gv500. Solves/reduces chance of setback and you are more prepared to protect your family while home should the need arise. I have two of them, one upstairs and one downstairs. Has worked well for me.

WardenWolf
May 1, 2013, 01:25 PM
why? its a shorter cartridge or something? and why would a .40 be less likely than a .45 to setback? keep in mind im not very familiar with many of these rounds
Some manufacturers may compensate for this by designing their factory cartridge to prevent setback. Dimpling the case or other methods are sometimes used to prevent the bullet from being pushed in too far. However, it's not a solution you see very often in .40.

The .45 just doesn't really seem to have this problem. I'm not sure why, but it's rarely an issue with both .45 and 9mm. Setback is, for whatever reason, primarily a .40 issue. This, coupled with its high pressure and the fact that virtually all guns chambered in it are polymer, makes for a dangerous combination. The poorly supported chamber in older Glocks adds to make it a recipe for disaster.

Potatohead
May 1, 2013, 01:29 PM
hey thx guys

Potatohead
May 1, 2013, 01:32 PM
thx for article steve

Muddydogs
May 1, 2013, 02:40 PM
I have been carrying a .40 for 5 years and have not had any set back issues. I read all the posts about how dangerous set back was when I first started carrying so I was always checking my rounds after a few chambering’s using new factory rounds as a guide. Once I started to carry my hand loads I of course new the OAL range of the rounds so checking is even more accurate and I have yet to find one that has set back. My pistols stay loaded except for cleaning and dry fire practice so the rounds are not chambered a lot.

As of right now my practice is to every once in a while transfer the top 2 rounds in the mag to the bottom and then about every 6 months check the rounds in my two carry mags for OAL and general wear. The only rounds I have pulled from the mags have been rounds that have developed an edge in the case where the base of the bullet rests. The bullet in these rounds gets pulled, the case resized and everything reloaded. I don't shoot my actual carry rounds but do shoot rounds loaded just the same except instead of new factory Gold Dots I picked up 1000 pulled Gold Dot.

Potatohead
May 1, 2013, 04:51 PM
the OAL range?

Potatohead
May 1, 2013, 05:05 PM
article was pretty interesting. made me feel better thats for sure

Muddydogs
May 1, 2013, 05:20 PM
the OAL range?
Nothings perfect, case heads can be different and the bullet base to ogive isn't always exact from bullet to bullet and depending on the nose design like an exposed lead bullet the measurements can be even further off. If i'm seating bullets to an OAL of say 1.125 it could very from 1.120 to 1.130. Gold dots are fairly close and stay around +- .003. I have loaded some pulled .40 bullets that vary as much as +- .010 and required I reduce the load as they showed some pressure signs at my normal .40 load. This is with 165 grain bullets. A couple thousands of difference is not going to make any difference.

WardenWolf
May 1, 2013, 08:14 PM
My friend nearly blew up his XD .40 with a set-back cartridge. Lucky I spotted it and told him to dispose of it.

TfflHndn
May 1, 2013, 08:39 PM
357 Sig is another round that can have setback problems because the case doesn't hold the bullet very firmly.

If you are really concerned about setback, get a bullet puller (the inertial kind, looks like a plastic hammer) and you can tap the bullet back to proper length or longer and if you load that caliber you can reseat it at the proper length. If you don't reload you can still tap the bullet out to a length comparable to others. If you really must unload and load daily, use a sharpie to draw a ring around the bullet at the case mouth. If the line disappears into the case, you know the bullet is setting back and you can tap it back out to the appropriate length.

Muddydogs
May 1, 2013, 09:15 PM
357 Sig is another round that can have setback problems because the case doesn't hold the bullet very firmly.

If you are really concerned about setback, get a bullet puller (the inertial kind, looks like a plastic hammer) and you can tap the bullet back to proper length or longer and if you load that caliber you can reseat it at the proper length. If you don't reload you can still tap the bullet out to a length comparable to others. If you really must unload and load daily, use a sharpie to draw a ring around the bullet at the case mouth. If the line disappears into the case, you know the bullet is setting back and you can tap it back out to the appropriate length.
Tapping the bullet back out and continuing to load it is bad JuJu. The case neck tension could be compromised, if its factory rounds the sealer they use will be broken and you are not sure of the neck tension. Plus unless you have a micrometer and measure the OAL its just a guess. If you don't reload then shoot the rounds ever once in a while before any set back and if in doubt just get rid of the round.

1SOW
May 2, 2013, 02:09 AM
The .357 SIG cartridge when new sort of made set-back famous. It was typically in a SD semi-auto and the short bottle-neck case doesn't provide as much neck tension/strength. Clearing the pistol at the end of the day and reinserting the same chambered rd led to lots of talk about bullet set-back problems.

As said, it's especially dangerous in high pressure cartridges like 9mm, 357 Sig and 40cal using SD hot ammo

gamestalker
May 2, 2013, 04:29 AM
Good question, and is an especially good time to address, considering so many new reloaders coming into this hobby, and at such a high rate.

As for what concerns set back presents, it can cause chamber pressures to increase unpredictably, and potentially to dangerous levels. I think a good example of this is, Speer did a test using a 9mm cartridge. they developed a normal load that was producing a reasonable average pressure of 28,000 cup at a given OAL. Then they used the same load, but this time they seated the bullet .030" deeper. The result was pressures went to 62,000 cup, that's over double the pressures as opposed to the original OAL.

Measure a single round, and then cycle it through your firearm, as you would normally do each time you load it for carry. Then take that one bullet and cycle it through the firearm 15 times or so, do it in the same manner as you normally would. When you finish, measure it again, calculate the difference and you'll then know if you have a problem, or not. If it sets back more than just a few thou, I would probably soft chamber to load each time from now on, rather than just dropping the slide. But if you experience a lot of set back, like more than .010" after only a couple times of cycling it, I would look closer at my reloading process, especially my crimp.

GS

Potatohead
May 2, 2013, 03:45 PM
muddy, i was meaning what is OAL?

Potatohead
May 2, 2013, 03:47 PM
use a sharpie

thx TFFL i will try that just to make sure

Potatohead
May 2, 2013, 03:51 PM
thx gamestalker..i will try that

Muddydogs
May 2, 2013, 04:16 PM
over all length of round. from bottom of case to nose of bullet.

steve4102
May 2, 2013, 11:11 PM
My friend nearly blew up his XD .40 with a set-back cartridge. Lucky I spotted it and told him to dispose of it.

Good job in catching that for him, but how do you know this round would have "blew up his XD 40"?

WardenWolf
May 3, 2013, 05:05 PM
Because the round was pushed back so far its shoulder was literally below the rim of the cartridge. Most likely sitting directly on and compressing the powder charge. As little as 1/10 of setback in .40 S&W will double the pressure inside the case, and this was at or beyond that. Even though it wasn't a Glock, which would make it more prone to case rupture, it would still have likely destroyed the gun or at least cracked the frame.

Potatohead
May 3, 2013, 05:13 PM
Good job in catching that for him, but how do you know this round would have "blew up his XD 40

i was wondering the same

steve4102
May 3, 2013, 05:34 PM
Because the round was pushed back so far its shoulder was literally below the rim of the cartridge

Did you read the article posted on set back in the 40. Pushed back all the way and no "Blow up".

918v
May 3, 2013, 07:10 PM
As little as 1/10 of setback in .40 S&W will double the pressure inside the case, and this was at or beyond that.

Can double the pressure, not will double the pressure.

If you enjoyed reading about "What is bullet setback and is it dangerous?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!