I went to the range today.

Was planning to sight in a new Holosun on my P320.

I ran 100 rounds of blazer brass with no problem.

Started to run two boxes of Remington green box.
The gun started to fail to eject.

When I would clear the jam I would sometime get two rounds plus the spent casing.

If finally jammed so badly I could not cycle the slide by hand. I freed it once I returned home.

Is it most likely the ammo or the gun?

I would guess the ammo, but I have had no experience with anything like this happening to me before.

I don't want to assume.

What do more experienced people think?

If it is the ammo should I just dump it in the dud bucket?

I will get back to the range next weekend to try again.

Based on the fact that the problem only happened after you switched to the Remington ammo, I want to blame the ammo, but there's a few things I'm not sure I'm understanding.

You said it's failing to eject, but when you cleared it two rounds plus the spent case are falling out of the gun. And then it finally jammed to the point that you couldn't cycle the slide by hand.

That doesn't sound like failure to eject...it sounds more like failure to extract a stuck case. How was the slide stuck closed? Is the spent case remaining in the chamber and refusing to come out? If so, what is causing that to happen? Are the abrasions inside the chamber, anomalies with the brass, damage to your extractor claw? Does the gun have problems cycling manually with that ammo, or is the problem limited to actual live fire?

Well a few things come to mind - did you try that Rem ammo in a different gun? Could be a bad batch.

Was it the correct caliber for that gun? I've seen guys do that, mistakenly of course, but it happens.

Did you try a different magazine?

Did the extractor claw break?

Was the 320 properly lubricated?

Was the recoil assembly oriented correctly? (important for subcompact size slides).

Good luck.

I just put five rounds in a magazine and hand cycled the slide.

I did that twice

They all ejected as normally.

Well a few things come to mind - did you try that Rem ammo in a different gun? Could be a bad batch. No only brought the p320 to the range

Was it the correct caliber for that gun? I've seen guys do that, mistakenly of course, but it happens. yes 9mm

Did you try a different magazine? yes I was using two different mags, happened with both.

Did the extractor claw break? seems unbroken

Was the 320 properly lubricated? seem to be for the first 100 rounds,

Was the recoil assembly oriented correctly? (important for subcompact size slides). yes

Good luck.

I would rule out the possibility of the gun being the issue FIRST. Try that same ammunition in other pistols. If they don't have problems, it's the gun. If you merely switch to another ammunition that pistol likes, you may never realize that pistol has issues with certain ammunition other pistols run without issue. I like knowing my handguns will run anything within reason.

So the round would jam and by jam would the slide be locked closed or would it come back but not eject the round?

So 2 additional rounds would “feed” from the magazine when manually ejecting the faulty/jammed round? Like the mag feed lips aren’t holding the rounds properly???

It almost sounds like the rounds are out of spec. It SOUNDS like running a smaller caliber in the wrong gun. (I know you said this isn’t the case) but I have experienced almost the exact same thing many many years ago when I ran .40 through a .45 1911. Took me several rounds before I realized what I was doing and the malfunction profile was very similar to what you are describing.

I don’t know anything about the OP’s expertise or experience with guns in general or the P320 in particular so it’s impossible to know exactly what to tell him, but a couple of thoughts.

First, it does seem like a problem with the ammunition. As mentioned all ready, using the wrong stuff can result in the problems described. Although American manufacturers are unlikely to use the designation, 380 ACP is known as 9mm Kurz, and it can sometimes be fired in a 9mm Luger pistol and cause the same sorts of issues as reported. There are also other cartridges that use "9mm" in their designation.

If it’s not (admittedly unlikely) something like that, the first thing I’d check is to see if the problem ammunition will chamber freely in the barrel. Remove the barrel from the slide and drop cartridges into a clean chamber. Check them all and note if there’s any hesitation for the case head to fall flush with the barrel hood extension. If they don’t drop in freely, then they are probably out of spec, and as demonstrated by the absence of failures with the Blazer ammunition.

If they chamber okay, then it’s possible that the failure to extract was due to an overloaded charge that caused excessive case expansion. On the other hand, failures to eject can also be caused by faulty, underpowered ammunition.

But keep in mind that if a case got jammed into the chamber so tightly that it couldn’t be extracted by hand, that was almost certainly due to the ammunition. The gun isn’t responsible for that unless the chamber was, just for example, very badly corroded or had some gross machining defect that caused the case to be gripped more tightly than normal.

Let us know what you determine.

I agree with testing the ammo in your chamber like Sigfreund suggested above. One other thing you might do is compare it visually to a round of the stuff that was working fine in your gun. Look for any minor dimensional or contour variances between the two.

My brother bought a Rock Island 10mm 1911 a few months ago. The first time we shot it, it ran great. Last weekend when we were out there we shot it again, and it choked every other round or so. It looked like a classic failure to extract, as the empty case was still in the chamber, and the extractor was slipping off over the rim.

I initially suspected extractor tension as the problem, as 1911s can be finicky about this, but it passed all the tests. Then I looked at the ammo. He had brought out a box of cheap Herters crap that he bought at Cabela's. The case mouth was not crimped at all, and what was happening was that as the gun was extracting the fired case, the edge of the rim would slam into the sharp edge of the case mouth of the round at the top of the magazine, and there was enough resistance there to overcome the extractor's hold on the rim, allowing it to slip off. Then the slide would slam forward again and shove the empty case back into the chamber. We shot a different brand of ammo, which worked fine, and when comparing it to the Herter's stuff, the edge of the case mouth was notably rounded. We could have probably fixed the Herter's ammo by running it through a crimp die, but there wasn't much left by that point so we just finished off the box.

Point being...not all ammo is created equal, and some minor variances can be enough to cause headaches for your gun.

Because it is quick and easy to do, I suggest popping the rear cover off of the slide, removing the extractor parts and inspecting the bore. The mounting screw may be a bit too long and could be interfering with the extractor spring. Or, some locktite (if used) could have dripped into the channel.

One hundred rounds with blazer and no problems.

I think the Remington is under powered.

Thanks for the advice everyone.

After shooting in competitions for over 15 years, the most likely problem is almost always the ammo, followed by cleaning, lubing and aftermarket modifications.

I have a 320 Legion that will stovepipe aluminum cased Blazer about once a magazine. I haven’t found any other ammo it won’t run. And I don’t have any other 9mm handgun that won’t reliably run that ammo.

I suspect that this may be a combination of factors. Specifically the increase in Mass of the slide in combination with Remington ammunition that may be a bit on the weak side. Note, Remington labels it's 9mm Kurz ammunition as 380. However they have also placed the 380 and 9mm Parabellum in identically sized boxes at times. It might be worthwhile to take a close look at the head stamp you your cases because someone at Remington may have put 380 ammunition into a 9mm box. Because someone who has never seen 380 ammunition might think that odd looking round is just a different bullet being used.

I would suggest that you set this Remington ammunition aside for uses in other 9mm pistols you own. Note, these are superb cases for reloading so I do have a rather considerable stash. It functions quite well in my LC9S Pro pistols and my P365 but I am someone who wont use an optical sight on a Defense Pistol.