[John in AR]

I recently encountered a problem that I've heard of, but never personally experienced before. On my .300 blackout pistol, using one certain brand of magazine and one certain fmj ammunition, the bullet tip occasionally hangs at the transition from the upper receiver cutouts and the barrel extension cutouts. (It's an inexpensive upper, from PSA iirc.) It's not done this before, but I've not used this brand of fmj ammo before and now with this combination it sometimes does. To be clear, it's not the ammo's fault or the magazine's fault. Once it started happening, with a flashlight I could easily see where the transition from receiver to barrel-extension has a very minor ridge on it. The bullet feeds straight in as it should, but sometimes the tip hits the minor ridge there and just stops in its tracks. Anyone ever experience that..?

This shows the specific problem I'm trying to describe; actual useful info starts about a minute in:

I've looked into how to correct it quite a bit online and have some polishing tips coming for correcting it; hopefully they'll come in by the end of the week and I can do it over the holiday weekend. I don't like the prospect of removing the barrel from the receiver, but that's really the proper way to do it, so I will.

Just wondering if this is something that's common or rare - I've never had it happen on any AR before.

 

[Dorobuta]

Never experienced it.

 

[BigEd]

I've had that happen a long time ago and I cannot specifically the which of the two poorly assembled, and both were, rifles had that problem. Or maybe both.

One was the first AR type rifle I bought and I knew nothing about them at age 20. Poorly home assembled POS-CAR by a co-worker of my father. It had an extended flash suppressor to make it legal.
The next was an Eagle Arms EA-15 Carbine and had pretty much all the same issues plus the front of the upper receiver extension itself was rough and too long. Something that would normally be caught at the factory; you'd think.🙄 Anyhow that one I think was the one and it being under the shop's full service warranty they repaired it or sent it to Eagle Arms for a new upper receiver.

So no as to fixing the problem myself.

I do understand the parts issues.

Somewhere there's a youtube video by someone who had assembled an AR out of pretty much all high end parts from several different makers and it refused to run from day one. Everything added up to no room for proper function.
Because of that my last AR build was all Aero Precision with the exception of the charging, handle, furniture and sights &optics. Oh yes and the muzzle device.

 

[John in AR]

I've never done an entire AR build; just done some pretty basic modifications & assembling. Most involved things have been some new triggers, safeties & one gas block (including enlarging the gas port). Gas block & gas port work was actually on this gun; but it wasn't a complete build, I just replaced the factory gas block with a click-adjustable one because of this being a short barreled gun.

I'd forgotten & didn't make the connection until looking at some things last night, but this gun has apparently had this happen before. When I tried an Elander or two in it, it jammed up a few times and I chalked it up to the gun not liking Elanders. I'd completely forgotten about about the Elanders not working in it; it was christmas a couple years ago and I'd forgotten all about it. It's the only failure I've ever had (that I recall, at least) with the Gen3 Elanders, so this may be an exoneration of that one failure.

If nothing else, it's another example of why to test, retest, change some variables and test some more. I've shot 2-3 thousand FMJ through this gun with no problems, but this failure last weekend was with a different brand of FMJ. It's fiocchi, which is good stuff, but I've not used this exact ammo in this gun before. I was using it to test some Hog Hammer SCHP stuff in the gun; the first three and last three rounds in the mag being hog hammer, and the rounds in the middle being the fmj since I only have one can of the hog hammer. The hog hammers fed & functioned fine, never hung up on that micro-lip, held the bolt open, etc. All good, no problems. But the new brand of FMJ's hung up two or three times per magazine; the nose of the round hanging on that lip like they'd hit a wall. It's the only FMJ it's done it with (with the exception of fmj's through the Elanders), and if I hadn't tried it, I'd have absolutely assumed that this Fiocchi fmj would run in the gun just like every other fmj I've used in it.

The shaping & polishing tips are supposed to be here tomorrow, so I may get to mess with it over the weekend.

 

[BigEd]

On a different type of Firearm but a similar issue.
Newer production of my favorite factory load for 9mm carry Ammunition has failed to feed in my Glock 17 pistols but in my 26 and 19 they run fine.
That's the Hornady 135gr +p Critical Duty.☹
In a way now I'm glad I never could wrangle down a whole case if it. Then again I'd have no trouble unloading it on someone else.

 

[John in AR]

+1, that's why I'm obsessive about testing & verifying. I've had only one feed problem in my G19, but it was persistent. It was only when using the old school federal hi-shok 147 grain JHP, in 10-round AWB-era magazines with their different followers. Any other ammo fed in those mags, and that ammo fed in any other mags; but that one combination failed constantly.

 

[John in AR]

Unfortunately I think I did irretrievably goober this upper, so decided to bite the bullet so to speak and replace it. At least it’s just the upper and not the full gun. I’m also taking this opportunity to go from this 8.5” barrel to a slightly-better 10” version.

That’s what I get for trying to take shortcuts, but at the end of the day it basically falls into the “oh well” category… If this is the worst thing that happens this year, that’ll be a pretty good year.