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What is bullet setback and is it dangerous?

Discussion in 'Handloading and Reloading' started by Potatohead, Apr 30, 2013.

  1. Potatohead

    Potatohead Well-Known Member

    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
  2. Potatohead

    Potatohead Well-Known Member

    EDIT: i think title should have been "what is bullet setback and HOW dangerous is it"...im sure its gota be somewhat dangerous
  3. CoRoMo

    CoRoMo Well-Known Member

    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.
  4. Fryerpower

    Fryerpower Well-Known Member

  5. WardenWolf

    WardenWolf member

    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.
  6. holdencm9

    holdencm9 Well-Known Member

    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.
  7. Drail

    Drail Well-Known Member

    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).
  8. SouthernBoy

    SouthernBoy Well-Known Member

    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.
    Last edited: Apr 30, 2013
  9. Manco

    Manco Well-Known Member

    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.
    Last edited: Apr 30, 2013
  10. Darkbob

    Darkbob Well-Known Member

    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.
  11. BADUNAME30

    BADUNAME30 Well-Known Member

    This question is best suited for the reloading forum.
  12. Potatohead

    Potatohead Well-Known Member

    Thx guys very good info as usual
  13. Potatohead

    Potatohead Well-Known Member

    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
  14. LJ-MosinFreak-Buck

    LJ-MosinFreak-Buck Well-Known Member

    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...~
  15. beatledog7

    beatledog7 Well-Known Member

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

    Potatohead Well-Known Member

    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?
  17. Potatohead

    Potatohead Well-Known Member

    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?
  18. Potatohead

    Potatohead Well-Known Member

    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
  19. Potatohead

    Potatohead Well-Known Member

    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
  20. steve4102

    steve4102 Well-Known Member

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