During the last monthly training hosted by Grant and friends, I encountered a weird malfunction, with limited input from either Grant or other people. The malfunction is this:
The bolt locked to the rear WITH rounds still in the magazine. I was doing a AR dueling tree type deal, and after the 3rd round, the bolt locked back. I peeked into the chamber really quick, and dropped the magazine to reload, pressing the bolt release afterwards. Afterwards I picked my other magazine up and to my surprise, it was almost topped off.
Grant said a spent casing could have flopped around the chamber and somehow caused the malfunction. Has anyone else experienced this or should I not even be worried? Seems like a tiny tiny likelihood of it happening ever again.
This has happened to me before several times on Al 10 rounders (not in a free state). I’m certain the issue is magazine related. As to what’s wrong with the magazine, I can’t say for sure, but in my case, I suspect that it is possible that the rounds are being jolted forward a bit (mags are old, loose base plates), and with a loose base plate, the magazine spring is shifting during recoil, causing the rear of the follower to push up against the bolt hold open “lever,” resulting in a bolt lockback despite there still being rounds in the magazine. YMMV.
That could be it. My GI mags are for training, and I use them to induce malfunctions as much as I can while I train. Didn’t expect it when it actually mattered though.
You somehow pushed the bolt catch while firing (just like pistol shooters getting a finger pressing the slide catch during firing) causing the bolt to lock back. Rare, possible if your equipment or hand positioning is there hit it.
Casing bashed into the bolt catch and locked it open. Rare, I have not seen it happen, but I guess it could be possible.
Spring or detent failure behind the bolt catch. There may be a failure of the spring/detent that keeps the bolt catch (pressing outward at the base of the catch) pushed “down” until it gets pushed “up” by the magazine follower. Debris or junk caught inside the bolt catch could do it.
Without the spring tension behind the bolt catch,the bolt catch can flop around during firing and bounce up to block the bolt—locking it open with ammo still in the magazine.
I vote #3
I will guess your bolt catch needs to be closely inspected. Make sure its not broken, spring and detent in good shape as well as a clean home for the parts.
If it’s happening with different mags or just one mag? If its just one mag then thats the problem . If it’s with all your mags then it’s the detent verifyied or not!:rolleyes:
I once had a rifle that would sometimes do the same when using PMAGs. It turned out the bolt catch was dragging on the side of the mag. With the upper removed, try inserting a loaded mag into the lower and watch for any motion of the bolt catch…