I had my Springfield EMP4 at the range today and towards the end of the session it began having a bit of a sluggish time chambering from slide lock when loading a fresh mag (it never failed though to go into full battery) so I ejected the round a couple times and noticed some setback to the naked eye. One round I re-chambered again to see if the setback would get worse and indeed it did. I did not have my calipers at the range though I knew it had to be greater than 1mm just looking at it compared to another fresh round. Ammo used was Blazer Brass 124gr. FMJ as a side note. When I got home I measured it and it was actually closer to 2mm on the one chambered twice, a little less than 0.6mm on the one chambered once.

I figured I'd do a sort of informal experiment where I would try the same ammunition in a couple of other pistols to see if the amount of setback was similar. I took a Glock 17 and a Smith and Wesson Shield and chambered fresh rounds from Blazer Brass 124gr. FMJ as well as some Fiocchi 124gr. FMJ to see if there was a difference in ammo setback between manufacturers.

What I found after one chambering was that the Blazer had a range of about 0.6-1.0mm of setback in the EMP4 and only 0.06-0.19mm in the Glock/Smith. I couldn't really see the setback with the naked eye in the latter two, though I could tell even without the calipers a few times with the EMP4 that the OAL had changed.

I then did the same test with some Fiocchi 124gr. FMJ and found this ammo to setback less in all 3 guns, with the EMP4 in the 0.12-0.2mm range and the Glock/Smith only in the 0.01-0.03mm range. Proportionally it is similar to the Blazer testing, albeit significantly less overall setback.

For another bit of data I noted through calipers that OAL of fresh unchambered rounds varied on the Blazer up to nearly 0.2mm. The OAL deviation on the Fiocchi was closer at under 0.1mm. Based on this I concluded that the worst setback on the Glock/Smith was within the standard deviation anyway so the setback was even more insignificant with these pistols.

Interestingly, after shooting probably in excess of 100,000+ rounds over the last 15 to 20 years I have never really thought about bullet setback and I've never had any issues other than perhaps a round that was chambered more than half a dozen times in a carry gun. It seems like the carry ammo that is usually jacketed hollow point has a much better crimp line around the top of the casing where the bullet is secured I assume to resist this very phenomenon of setting back.

What I have gathered from this is that although I have never had a problem in the thousands and thousands of rounds of Blazer Brass it does appear to be more easily set back. Though perhaps still insignificant in most guns, the EMP4 causes this round to setback significantly, possibly due to the angle of the feed ramp or perhaps as the gun got dirtier coupled with the chamber not being as smooth as some other guns? I don't know what if anything it was catching on to slow it down and push the bullet back into the casing more so than other guns do.

I am wondering if I did not catch it when re-chambering a round if it would have mattered. I'm not sure of the pressures with a setback round if it would equate to a +P or +P+ round? A proof round? How much setback would be too much? I figured that many of us probably shoot rounds that are maybe slightly setback from time to time without ever thinking of it and nothing happens, but when we can visually see a significant difference then perhaps that's the time to pull it aside and discard the round.

I would be curious to know what all of you think about what the acceptable amount of setback is and what you've encountered in your experience. Again, I have known in the past that multiple chamberings, such as with carry ammo, is frowned upon as it can happen, but usually this is much more than once or twice. This experiment was to show just simply from one time chambering a round (with the exception of the initial round that was chambered twice). I could've extended the experiment and chambered the same round two or more times because technically if you rack a round out and then rack it back in, then that's 2 chamberings--such that if the round has set back some after one time then it is feasible to think it would be worse with a second chambering. Usually when a round is chambered at the range it never comes out of the chamber unless it's fired, but when competing sometimes you'll have a round left in the chamber at the end of a stage that needs to be racked out and I rarely inspect that round--I've always just put it back in my range bag and shot it later without issue.

I only have one photo of the raw image at the range of a a fresh round compared to the one that was chambered twice in the EMP4. I should’ve taken photos of the caliper measures but that’s pretty boring.

If for no other reason than abundance of caution, I wouldn't recommend firing the cartridge on the right.

Yes of course I agree, anything that is blatantly seen with the naked eye is trashed.

I'd be willing to bet that your specific issue is related to the EMP4 feed ramp being as long and steep as it is. Looking at mine, I imagine that design puts more rearward force on the bullet during the feeding process than a lot of others.

That's some pretty significant setback, but I'll bet that round would still fire just fine. I wonder how many have done that during the initial chambering in that gun and we've never even known. I agree though, now that you've seen it I'd trash it (or pull and reload it) just to be safe.

quote:

Originally posted by 92fstech:
I'd be willing to bet that your specific issue is related to the EMP4 feed ramp being as long and steep as it is. Looking at mine, I imagine that design puts more rearward force on the bullet during the feeding process than a lot of others.

That's some pretty significant setback, but I'll bet that round would still fire just fine. I wonder how many have done that during the initial chambering in that gun and we've never even known. I agree though, now that you've seen it I'd trash it (or pull and reload it) just to be safe.

Yeah I would bet it happened all range session and I had no issues to speak of. Few times the slide went home quite smoothly so perhaps those times it was setback less who knows.

After doing some more research, the literature suggests that when it gets to 0.010" setback or greater then there could be a problem. When converting the millimeters to inches I never come close to that with the Glock or Smith, as they hover in the accepted range of a few thousandths. It's not really even an issue with the EMP4 with the Fiocchi, it seems that it's the Blazer and EMP4 combo. I'll just make sure to only chamber one time when shooting this gun and if I can remember maybe just save the Blazer for my other pistols and feed the EMP4 Fiocchi or maybe S and B.

On the one hand, who would ever risk whatever liabilities are associated with defying conventional “wisdom” regarding a supposed safety issue by saying not to worry about something like that?

On the other, if there was a significant danger associated with the setback of bullets in handgun cartridges, why don’t we hear of guns blowing up all the time? Although I wouldn’t hazard a guess about the percentage of gun owners who are completely ignorant of the concerns about bullet setback, I’d bet the rent that it’s pretty high. I’ve seen pictures here of 40 S&W cartridges right out of the factory box showing clearly visible setback. When the question is then raised here, we see urgent warnings not to fire those rounds, but how likely is it that gun owners who aren’t active on forums like this would recognize the issue and not fire them? Spending any time at a public range makes it clear that many shooters are completely ignorant of issues that are far more obvious than the supposed dangers of bullet setback.

But yes, if you see any bullet setback in a cartridge, absolutely don’t fire it.

quote:

But yes, if you see any bullet setback in a cartridge, absolutely don’t fire it.

Incidental +P

Yes, it is interesting to think about all of the bullets shot every day that are potentially set back yet we don’t hear about kabooms left and right like you think you would if it mattered.

from a reloading standpoint it doesn't look like it has a crimp? can you push a factory bullet in easily? you can't on my reloads and they are dead on spec.

I called Springfield and they said their chambers are tight so that coupled with the steep feed ramp has got to be the issue I think. Gonna send it in and hopefully it will be smoother when it comes back. This is the second trip back to the mothership for issues, ugh. Will keep posted.

That's +P+ if I ever saw one.

quote:

Originally posted by bionic218:

quote:

But yes, if you see any bullet setback in a cartridge, absolutely don’t fire it.

Incidental +P

After seeing stuff like this, upside down primers and such, I case guage all my ammo. Reload or factory. It may have been just one of those things.

When I was policing, we had quarterly weapons inspections. At some point (2001)one of the firearms instructors came in and had everyone download all their ammo and lay a ruler across the top of the rounds. From that point on, officers were told not to load and reload the same round if they unloaded their weapon each night/day. They were told to leave the gun loaded and buy a small safe or handcuff the gun behind the trigger to keep it from being able to be fired. They were told to rotate the rounds in their magazines to avoid rechambering the same round multiple times.

If a round was showing setback it was replaced by the box in the sgts office. The suspect rounds were taken apart with a kinetic puller and thrown in the trash.



I found this happens a lot when we carried the 357SIG and the 9MM, both rounds didn’t have a roll crimp but a taper crimp. Since then I’ve checked my carry ammo, as I unload it often when going into my kid’s schools (I’m retired). Haven’t had it happen since I switched to 45ACP(it’s a tapered case too) but that might be due to the bigger surface area of the projectile.

Anyway, don’t shoot any rounds that show set-back, tear them down or throw them into the trash where they will be buried in a landfill.

I don’t use any allowable setback beyond what is shown in my reloading manual (max 1.169, min 1.0), if a round shows it by laying a steel ruler across the one I use, I tear it apart or trash it. A new box of ammo is much cheaper than a new gun/barrel.

This thread caused me to go grab the magazine out of my carry pistol and inspect the rounds. The top two (that get ejected/rechambered about weekly) were each set back about 1/2 mm. Visible, but not worrying.

It's an excuse to shoot the self-defense ammo up and replace it.

Also interesting to note is I called CCI and explained to them what I was discovering and they said that their range ammo is built with thin jacket walls such that it is more prone to setback maybe vs. other rounds. They said that it is meant to be chambered once and only once, which is sort of surprising as I feel like any bullet should be able to be chambered at least a couple times for reasons mentioned above.

quote:

Originally posted by LincolnSixEcho:
Springfield steep feed ramp has got to be the issue

I have two Springfields that came with steep feed ramps. They had to be recontoured, not just "polished" to feed hollowpoints at all. I haven't seen setback of my usual Federal JHP or any RN.

Federal seems to be the best about puting a cannelure in the case at the base of the bullet to prevent setback. I have a device to put a case cannelure in .45 ACP reloads with light plated or jacketed bullets. Not needed with 200 gr cast or 230 gr plated.

Years ago when CCI brass was among the least expensive brass cased ammo out there, I noticed that their empty brass felt a little 'light' compared to Federal\Remington\etc.
A fellow shooter told me that he tried to reload the CCI, but it crumpled every time he put it in his press. Now I know why.

quote:

Originally posted by LincolnSixEcho:
Also interesting to note is I called CCI and explained to them what I was discovering and they said that their range ammo is built with thin jacket walls such that it is more prone to setback maybe vs. other rounds. They said that it is meant to be chambered once and only once, which is sort of surprising as I feel like any bullet should be able to be chambered at least a couple times for reasons mentioned above.