AR15 unknown problem

[gunguy123]

Hey guys I need some help. I recently purchased a 14.5" BCM carbine upper. I put in a Daniel Defense BCG. And I put the completed upper on a Ruger SR556 lower (temporary until I get a BCM lower). I went shooting at an indoor range that issued 45 gr .223. Numerous failures began to show. First, after every 5 rounds or so, the spent shell casing and a new round would get stuck between the BCG and the chamber. And eventually after enough rounds were fired, the BCG was not even moving back.I had to manually pull back the charging handle to chamber another round. Will someone tell me what the problem is? I think that the 2 rounds stuck in the chamber could be because of the buffer tube on the SR556 lower. It is not "H" marked and I do not know the quality of it. And I'm not too sure about the bolt carrier not moving rearward. Could it be that because it is a full auto carrier it needs more energy and therefore more grains to push it back? Any advice and help would be greatly appreciated.

[djleisure]

Definitely sounds like it's short-stroking for some reason. Were these reloads that you were shooting? Did you put a little oil/lube on the BCG?

[PyroFox79]

Try using 55grn. Maybe the charge in the 45grn is too weak ot inconsistent for a semi? Just a thought.

[damndave]

Try some different ammo. PMC is a hotter load and might help if it is short stroking.

Make sure it is all lubed up well.

[AeroEngi]

I'll reiterate what everyone's been saying here...lube your bolt and carrier really well. Use some good quality grease. I learned this the hard way. AR bolts have to be run wet. Also IMO, your issue might be because of the 45 gr ammo you're using. Trying using a hotter load (55 gr PMC or 55 gr Federal XM193). Since your buffer has no markings of what weight it is, there could also be a possibility that your buffer is too heavy which might be causing the short stroking of your BCG.

[b.faust]

Also double check that you have the correct length buffer spring in. Dumb as it sounds, a friend was having some short stroke issues, and it turned out he had the wrong buffer spring (used rifle he bought, and never checked)
Proper carbine buffer and he was gold.

[GMG]

Hey guys I need some help. First, after every 5 rounds or so, the spent shell casing and a new round would get stuck between the BCG and the chamber.

The spent shell casing and the new round tangling in the BCG could also be an extractor problem. I cured that problem by installing a BCM extractor spring kit.

[gemini1]

The OP was issued ammos by the range, which may mean that they wont allow the OP to use his own ammo. OP are you in NorCal? would this be Jackson Arms? I'm just guessing but maybe they gave you underpowered rounds just to be safe? Those guys had some issues with their back stop when some a**hole shot AP rounds that almost went through the other office next door to them.
I've shot hundreds of 45 gr Winchester from walmart with no issues on my 16" BCM.

[bjl333]

It kinda sounds like you're undergassed, meaning the ammo doesn't have enough juice to cycle the action completely. This is compounded by the action getting dirty as you shoot hte rifle. You mentioned 223 and I bet your upper is a 5.56, next time try some 5.56 ammo and your problem should go away!

[missiontrails]

You need to try some 5.56 NATO rounds before you think that you have problems. There is a reason barrels are stamped .223 and 5.56... and it has more to do than just chamber throat size. Most people consider Colt to be reliable, right? Well we have 2 Colts in the family that are stamped 5.56 that just can't run reliably on inherently lower pressure .223 rounds. Magic secret: GAS PORT SIZE. Not always, but often times. If you had to take a wild guess, would you think the gas port hole on a .223 barrel and a 5.56 barrel are EXACTALY the same size? Be prepared, there are people in these forums that will next tell you that your rifle is a POS if it won't cycle both perfectly. The people who claim that are lucky enough to have overgassed 5.56 rifles. An overgassed 5.56 rifle shooting .223 will feel the same as a correctly gassed 5.56 rifle shooting 5.56. Granted, there are some brands of .223 that are "hotter" than others, and those will work great.

[Tweak338]

OP where are you located?
Sure someone will help you figure it out.

[dieselpower]

and the Stag guys chuckle under their breath....

If the 55gr ammo stops this problem, then you know the upper will not work with all ammo. Don't buy the cheap stuff either. People who have reported this problem on BCM uppers state the cheap stuff is the culprit. Some uppers are just picky eaters.

[thenodnarb]

Hey guys I need some help. I recently purchased a 14.5" BCM carbine upper. I put in a Daniel Defense BCG. And I put the completed upper on a Ruger SR556 lower (temporary until I get a BCM lower). I went shooting at an indoor range that issued 45 gr .223. Numerous failures began to show. First, after every 5 rounds or so, the spent shell casing and a new round would get stuck between the BCG and the chamber. And eventually after enough rounds were fired, the BCG was not even moving back.I had to manually pull back the charging handle to chamber another round. Will someone tell me what the problem is? I think that the 2 rounds stuck in the chamber could be because of the buffer tube on the SR556 lower. It is not "H" marked and I do not know the quality of it. And I'm not too sure about the bolt carrier not moving rearward. Could it be that because it is a full auto carrier it needs more energy and therefore more grains to push it back? Any advice and help would be greatly appreciated.

With a carbine upper, it should be cycling that ammo. Check your gas block. What kind is it? Is it a FSB or some other type of gas block? maybe the gas tube isn't pinned or something, and the tube has slid forward and isn't lined up right. You said the bolt wasn't even moving near the end there, and that tells me it isn't unlocking the bolt, which means gas isn't even getting down the gas tube.

Good luck

[AR-15 Rep]

There could be a few different problems ranging from ammo to this being a used upper that had a problem in the past. Best thing is to break it down and go through the upper checking the gas tube, installed properly, front sight ( base or gas block ) evidence of leakage etc. How was it as far as hitting the target and if you had to crank the sights to get it on paper. There are numerous things to start checking. I would before firing it again with another type of ammo, check everything... It could be ammo and then again it could be something that may be a bigger problem. With it having a down grade of function, something is going bad and could get worse... Safety first, check everything the best you can. If you need more help, give me a call and I can help talk you through some possibilities and help troubleshoot.

[TKM]

AR 15 unknown solution.