AR 15 FTF issue...

[TurboChrisB]

OK, gonna tap the collective wisdom of the board here...bought a new Bravo Company 5.56 upper from a board member a few weeks ago. Took it out to the desert to shoot and I'm having issues. Jams with the bolt open after one shot and I have to cycle the bolt to chamber the next round. Happens more often than not. But once in a while I then get to shoot the rest of the mag after 4 or 5 rounds. So, BCM upper. Using an Colt bolt carrier and a bolt I bought from Rifle Gear (don't remember the brand).
I tried mags that a friend brought back from his deployment....mags I had from my last AR, and New mags from two manufacturers...so I've ruled out the mags...tried the upper on two different lowers..both new..so I think I've ruled out the lowers causing a mag issue..it has to be a issue with the upper. Was shooting wolf ammo....but also ran some winchester...didn't make a difference. So not the ammo....Oiled the crap out of it...not sure what else to try...What would you guys suggest?

Thanks

[Josh3239]

Jam goes on toast. Tell us more. The bolt is just locking back, there is nothing in its path? Is it stuck in the extention tube? Is the BHO catching it? I am not really understanding the issue, you tried different lowers and mags and still the same problem. Did you try swapping out the bolt group?

[TurboChrisB]

Yes the bolt was locking back I didn't see anything in it's path....thinking if there was it wouldn't load a round the next time I cycled the bolt...only have one BCG but am likely ordering another this week for my next project..and yes, I had the same problem with two lowers, two ammos, multiple mags and one upper. What does BHO stand for? The buffer is free and working properly so I don't think it's the buffer tube. I'm leaning towards the BCG somehow...

[Josh3239]

So it isn't getting caught up on any rounds or any thing? That is weird. BHO is bolt hold open. Is it engaging when this happens? Does this happen if you hand cycle it (unloaded and loaded)?

[stitchnicklas]

bho is on the lower ,so you used different lowers that function fine with other guns,maybe check out where the bolt catches on the bho???

[jak77]

gotta be something fishy with the upper or bcg. I agree with other and try swapping out bcgs and see if this eliminates the problem

[DB2]

Is this the same upper that you posted a pic of a couple weeks ago? If it is, I see you have a flip down front sight. Is I canted? If it is it may not be lining up with the port. Is the gas tube straight? If it's off a bit, it will rub or catch the gas key. Sounds like a short stroking issue, since you have ruled out mags.

Also check for excessive gas leakage where the tube inserts into the front sight base.

[Josh3239]

DB2 that is an excellent point. Check out the gas tube in the upper, perhaps it isn't straight. Is there any damage/unusual wear on the end of the tube in the upper?

[TurboChrisB]

Good info, thanks guys...I'm gonna disasemble it tonight and check the gas tube and reassemble it....next time I fire it I should have another BCG, so between double checking and the BCG I hope to get it sorted out.....

[TurboChrisB]

OK, so I've been messing around with this for a while and here is where I'm at. I took the gun apart (gas tube, gas block) and re-assembled it...went to function check and realized that the FTF would occur just cycling rounds...good news. At least now I will know when I've fixed it without having to drive to the desert. Then I took it down to RifleGear on a Plum Crazy lower. They looked at it and came to the conclusion that it was a combination of my Colt SP1 bolt carrier and the tall, wide non-mil spec hammer that comes on the Plum Crazy lower. Their advice was a new trigger group or mil the hammer. OK, so I went home and called New Frontier Armory which is where I purchased the lower and talked to them. VERY helpful staff at New Frontier Armory. Cant say enough good things about them. He called and spoke to riflegear and concurred that the only apparent cause was the SP1 bolt carrier. Apparently they have a little extra material in just the wrong spot to interfer with the hammer. And out of 300 plus lowers sold the first one with a failure to feed issue. OK, so I pulled the hammer and milled it down...no improvement. Then it occured to me to PULL the hammer out....and still...no change..every other round or so it won't cycle the following round. So it's NOT the hammer. I would normally say then it must be the mag...but I've tried 4 different manufacturers of mags. The second 15 rds in a 30 rd mag do seem to feed better than the first 15 though..I just received a NEW BCM BCG and of course it doesn't make a difference. I also tried using my RRA lower with no difference.

So now I'm pretty much at the point where I guess I'm calling Bravo Company tomorrow and barring any fix over the phone...shipping it in to them and see if they can figure it out. Cause I don't know what else to check. Has anyone experienced "finicky" feeding cause of mags? This is my first AR in 10 years...the last one was a Colt and it would feed everytime with any mag....but I'll be damned if I can figure this out.
I'll post some pics in the morning.

[visualnewbie]

Have you tried using another lower with that upper? You might want to try that out also if you haven't yet...

[TurboChrisB]

I have two new plum crazy lowers and one RRA lower....same with them all.

[Josh3239]

I still need that other question answered. Is the bolt hold open actually engaging the bolt or do the actions just freeze up?

... and realized that the FTF would occur just cycling rounds...good news.

You mean semi auto action? So if you hand cycle them all is good? Out of curiousity what buffer assembly and stock assembly are you using?..

Just send it to BCM, they should fix it.

[TurboChrisB]

No, the bolt hold open is not engaging it, and when I hand cycle it occurs also, One of the plum lowers has the original CAR stock it came with, one I swapped to a ACE stock with Carbine buffer and the RRA has a Mapul CAR stock.

[Josh3239]

Dam that is weird.