The weirdest thing happened to me the other day...

[lernerk392]

I went to the range the other day and only shot two guns (my 10.5 AR (.223) and my Hellcat pistol (9mm)).

I noticed right away that my action wasn't locking back after the last round on the AR. I was using a different ammo than I first shot it with (fairly new gun), but it was the same grain and both were 223. It was ejecting brass and cycling fine, but there was one time where I pulled the trigger and nothing happened. I thought I had a bad cartridge/hangfire or even a squib, but what really happened was it didn't even strip the next round off in the mag.

Next, went and shot the Hellcat. And wouldn't you know, it failed to lock back on the last round as well! The mag is a basically new factory mag, shot it in the gun with the same grain ammunition as before. This pistol is more broken in and has always locked back. I was wondering if I was limp wristing all of the sudden or riding the slide release, but I wasn't.

• Both guns had one instance where they did lock back, and it was on a noticeably hotter round last round.

• Both were shot with factory ammo, functional magazines, both are clean, maintained, and relatively new/not worn.

• Both guns had fired maybe a hundred rounds each before with zero issue, always locked back.

I will be going back to the range next week with another brand of ammo and different mags. Will bring the old stuff to do an experiment to hopefully find out what the culprit is. I am looking forward to sniffing out the problem.

I am not the most well versed shooter out there so maybe its me, but I've shot these exact guns before and several others with no problems (at least not of this nature, skill is a whole other animal ).

Just thought I'd share just in case someone had some wisdom to impart upon me. I am all ears, thanks

TL;DR: Went to range, fired both an AR and handgun, both failed to lock back on last round. Hasn't happened before with same guns or any other guns, however just so happened to occur consistently in two different firearms on the same range trip.

 

[Ignition Override]

lernerk392: you might want to describe which brand of ammo.

Even Winchester “white box” and Win. Forged (gosh-what crappy ammo!), bought at Academy, caused a Few ‘won’t cycle’ malfunctions in a German-proofed 9mm Sig and the CZ-PCR.

These were the only malfunctions in those guns, with over 1,000 total rounds of various fmj brands used in each gun.

The Russian Wolf “ brand” (a marketing name in the US) of 9mm ammo functions fine in my 9mm handguns

 

[Archie]

Action not locking - continuously - is an indication of a couple possibilities.

One is the action being so grimed up the hold open mechanism cannot reliably operate.

Two is lack of power in that type or lot of ammunition to move the bolt or slide to the fully rear position for the hold open mechanism to operate.

The statement about not stripping the next round from the magazine is usually an indication the cartridge didn't have enough 'impulse' to drive the bolt or slide far enough back to engage the next round. Which can be a problem with fouling or under powered ammunition.

Obviously, I don't know which from here. But I think your plan to try different ammo is a good one. Before you shoot the next attempt clean the slide rails or bolt raceway to insure nothing is gumming up the movement. (Yeah, clean the bore as well; that won't alter the problem much, but it's a good idea.) While cleaning, make sure the chamber is clean as well, to prevent the case being slowed down from opening.

 

[twofewscrews]

Ignition Override is probably on the right track. I have a PCC that eats everything I throw at, FMJ, HP, FN, but anything Winchester, especially "white box", and Federal Syntech create FTF's and FTE's like they're going out of style.
I have a Savage B-22 (.22lr) that won't eject Winchester M-22. The Winchester M-22 crap also fails to fire 3 out of every 10 or so shots in my 10/22 whereas every shot I've fired from my B-22 has worked minus the ejection.
I stay away from Winchester ammo in general now.

 

[lernerk392]

lernerk392: you might want to describe which brand of ammo.

Even Winchester “white box” and Win. Forged (gosh-what crappy ammo!), bought at Academy, caused a Few ‘won’t cycle’ malfunctions in a German-proofed 9mm Sig and the CZ-PCR.

These were the only malfunctions in those guns, with over 1,000 total rounds of various fmj brands used in each gun.

The Russian Wolf “ brand” (a marketing name in the US) of 9mm ammo functions fine in my 9mm handguns

The 223 ammo is that PMC Bronze stuff. I've shot white box and academy ammo (Monarch) and it ran fine. Going to pick up some more of that and test it out. The 9mm was Sellier and Bellot which I'm pretty sure ran fine in my pistol before, but I'll try a heavier grain maybe

 

[lernerk392]

Action not locking - continuously - is an indication of a couple possibilities.

One is the action being so grimed up the hold open mechanism cannot reliably operate.

Two is lack of power in that type or lot of ammunition to move the bolt or slide to the fully rear position for the hold open mechanism to operate.

The statement about not stripping the next round from the magazine is usually an indication the cartridge didn't have enough 'impulse' to drive the bolt or slide far enough back to engage the next round. Which can be a problem with fouling or under powered ammunition.

Obviously, I don't know which from here. But I think your plan to try different ammo is a good one. Before you shoot the next attempt clean the slide rails or bolt raceway to insure nothing is gumming up the movement. (Yeah, clean the bore as well; that won't alter the problem much, but it's a good idea.) While cleaning, make sure the chamber is clean as well, to prevent the case being slowed down from opening.

I'm really banking on the ammo not being "hot enough" cause there was a round that had some extra kick and the bolt locked back like normal. That was the case with both guns.

 

[citizenconn]

With the AR, try a different mag if you get the same results with the first mag not locking back. I usually Ballistol the heck out of mags with a sticky follower/spring and that usually fixes the problem. If it still does not lock back, check to see if your gas tube is making a good seal with the gas key and that the gas block has not moved or come loose. 90% of the time when I have an AR cycling problem it is my magazines. Good luck.

 

[theotherwaldo]

How cold was it?
That can affect functioning... .

 

[lernerk392]

How cold was it?
That can affect functioning... .

It was only about 60 degrees. But that would explain why it happened in two completely different guns

 

[theotherwaldo]

I've had magazines that I had to de-grease and graphite up if I wanted them to work at below 70 degrees... .

 

[jeepnik]

Clean them.

 

[Charlie98]

General question: you say your AR is ‘fairly new.’ Has it been cleaned since you bought it, and since the last range session? I’m not a big gun cleaner guy, but I do clean new to me guns… to either clean all that preservative yuck out of a new firearm, or make sure a new-to-me gun is properly clean and lubed. I also put a new AR into service last week, I run the bolts wet for the first 200-300 rounds… it solves a lot of problems.

 

[DustyGmt]

A buddy of mine had the same issue with a S&W M&P 9mm Shield that was relatively new, he had only maybe a few 50rd boxes of ammo through it at that point, it wasn't locking back on the last round and I thought perhaps the fact it was a pretty brand new recoil spring that maybe the steel case was generating just enough pressure to cycle but not enough to lock the slide back or something so I had him put a couple 9BPLE +P's first in the mag and when he finished the mag, the slide did not lock back.

At that point the state trooper we were shooting with was scratching his head as well, he suggested just taking the gun down into the few separate parts and wipe em down and put it back together and then the gun started to function properly. What gets me is the gun was wiped down and cleaned but it was hardly dirty, couldn't even really tell it had been shot but maybe worth a try, just take it down, hose it out and wipe it down and try again.....

 

[45/30-06OKIE]

A buddy of mine had the same issue with a S&W M&P 9mm Shield that was relatively new, he had only maybe a few 50rd boxes of ammo through it at that point, it wasn't locking back on the last round and I thought perhaps the fact it was a pretty brand new recoil spring that maybe the steel case was generating just enough pressure to cycle but not enough to lock the slide back or something so I had him put a couple 9BPLE +P's first in the mag and when he finished the mag, the slide did not lock back.

At that point the state trooper we were shooting with was scratching his head as well, he suggested just taking the gun down into the few separate parts and wipe em down and put it back together and then the gun started to function properly. What gets me is the gun was wiped down and cleaned but it was hardly dirty, couldn't even really tell it had been shot but maybe worth a try, just take it down, hose it out and wipe it down and try again.....

Holy cow! 9bple +p+ in a Shield??? I bet that rocked his world lol. I've shot one in a Glock 48 and it was interesting.

 

[DustyGmt]

Holy cow! 9bple +p+ in a Shield??? I bet that rocked his world lol. I've shot one in a Glock 48 and it was interesting.

Didn't lock the slide back, so it obviously wasn't a problem with power, but just taking it down to its few parts, wiping it down and reassembling seemed to be the trick.

Never had that problem with a glock

 

[Carl N. Brown]

Some new guns come with a preservative rust preventive coating that is not a good lubricant.

 

[lernerk392]

General question: you say your AR is ‘fairly new.’ Has it been cleaned since you bought it, and since the last range session? I’m not a big gun cleaner guy, but I do clean new to me guns… to either clean all that preservative yuck out of a new firearm, or make sure a new-to-me gun is properly clean and lubed. I also put a new AR into service last week, I run the bolts wet for the first 200-300 rounds… it solves a lot of problems.

Yes! Both were cleaned before the range trip. Funny enough, they weren't cleaned before the prior range trip (their first trip) and locked back with whatever factory gunk was still in there. But for now, I've stripped both down and did as much cleaning as I could. Not much came off/out cause they weren't that dirty to begin with, however like Dusty shared, that might not be an indicator of anything. We'll see what happens

 

[lernerk392]

Didn't lock the slide back, so it obviously wasn't a problem with power, but just taking it down to its few parts, wiping it down and reassembling seemed to be the trick.

Never had that problem with a glock

That's a great point. I'll try shooting the same ammo first (after a wipe down), and then if it still doesn't lock back, I'll move to hotter ammo.

 

[DustyGmt]

Holy cow! 9bple +p+ in a Shield??? I bet that rocked his world lol. I've shot one in a Glock 48 and it was interesting.

The idea being, I thought if any cartridge could knock some sense into that gun to make it act right, it would be the 9BPLE+P.

I have shot a few magazines of 135gr Hornady Critical Duty +P right alongside standard pressure 135's and I honestly could not even notice a difference at all in recoil impulse. I would like to see some chrono data of those two loads, I wondered if maybe Hordnady was running a scam, but I could never say that without chrono data. The 9BPLE on the other hand, is some spicy stuff. Probably not the best route to go for carry ammo for a short barreled 9mm

 

[koz4guns]

I’m not sure about the AR but on the Hellcat are you sure you weren’t hitting the slide stop with your thumb?

90% of the time when I have a handgun that doesn’t lock back on the last round it’s me not the gun.

 

[45/30-06OKIE]

The idea being, I thought if any cartridge could knock some sense into that gun to make it act right, it would be the 9BPLE+P.

I have shot a few magazines of 135gr Hornady Critical Duty +P right alongside standard pressure 135's and I honestly could not even notice a difference at all in recoil impulse. I would like to see some chrono data of those two loads, I wondered if maybe Hordnady was running a scam, but I could never say that without chrono data. The 9BPLE on the other hand, is some spicy stuff. Probably not the best route to go for carry ammo for a short barreled 9mm

Yeah that Federal load is spicy as heck for a 9mm... Of course I still prefer a 230gr 45acp load but with proper shot placement and as long as an attacker isn't on drugs or isn't very motivated to harm you, most modern quality self defense rounds will stop a threat.

 

[lernerk392]

Range Report for the AR:
Tried different magazines and different ammo. The problem of not locking back still persisted with the new magazines and new ammo. When using the same PMC 223, I had 9 double feeds (?) and twice when it didn't strip the next round. Happened at least once with each of the different magazines.

*the question mark is because I’m not 100% sure. But I know that the spent casing was always ejected. Should’ve taken a picture, but here’s what it looked like:

One round was always hung up on the topside of the bolt.

I kept all the rounds that happened with, and it was only while shooting the PMC, not once with the other brand I brought. Here’s a pic of some of the rounds once they were cleared:


Takeaways:
Still not locking back with change of ammo + mag. Feeding malfunctions with the PMC, not other ammo.

Starting to believe that it may be a problem with the gun itself? I’ve cleaned and checked parts, nothing looks worn or broken. Checked gas key path and it’s clear. Gas rings look fine. Gas tube is solid.

Any guesses/suggestions are welcome. Thanks

 

[45/30-06OKIE]

Range Report for the AR:
Tried different magazines and different ammo. The problem of not locking back still persisted with the new magazines and new ammo. When using the same PMC 223, I had 9 double feeds (?) and twice when it didn't strip the next round. Happened at least once with each of the different magazines.

*the question mark is because I’m not 100% sure. But I know that the spent casing was always ejected. Should’ve taken a picture, but here’s what it looked like:
View attachment 1115544
One round was always hung up on the topside of the bolt.

I kept all the rounds that happened with, and it was only while shooting the PMC, not once with the other brand I brought. Here’s a pic of some of the rounds once they were cleared:
View attachment 1115543

Takeaways:
Still not locking back with change of ammo + mag. Feeding malfunctions with the PMC, not other ammo.

Starting to believe that it may be a problem with the gun itself? I’ve cleaned and checked parts, nothing looks worn or broken. Checked gas key path and it’s clear. Gas rings look fine. Gas tube is solid.

Any guesses/suggestions are welcome. Thanks

I dealt with a similar issue on a 308 AR and the gas tube was not sized correctly and was leaking from inside the gas block... Had all kinds of problems, such as cycling perfect, not cycling at all, jamming rounds into the upper receiver, and just refusing to pick up the next round. No matter what PMAGS or brand of ammo I used it did this. So I found out where it was leaking and put a new gas tube in it and now it cycles perfect every time.

 

[Bazoo]

Check the gas rings in your bolt? Make sure they are correctly not aligned. Gas key on carrier still staked and tight?

 

[lernerk392]

Check the gas rings in your bolt? Make sure they are correctly not aligned. Gas key on carrier still staked and tight?

The gas rings aren't aligned and the gas key is staked very well with no movement at all.