Ar15 BCG doesn't look right

[Stangler]

Yes, let's see the buffer tubes....

 

[VortecK1ng]

Yeah it's looking like the tube is too short or something to do with it. All 3 uppers work on 2 of the lowers, 0 of the uppers lock back in the 1 lower. Swapped all tube/spring combos to each one same result with a little more give but just not enough with one of the combos.

Would it hurt to cut like a ring of coil off the spring and see if that fixes it?

 

[bolus]

Yeah it's looking like the tube is too short or something to do with it. All 3 uppers work on 2 of the lowers, 0 of the uppers lock back in the 1 lower. Swapped all tube/spring combos to each one same result with a little more give but just not enough with one of the combos.

Would it hurt to cut like a ring of coil off the spring and see if that fixes it?

I would not cut anything since these parts should all be interchangeable. that will also effect the spring and it may not cycle well when firing. I still suspect the bolt is catching on something on the way back, like the lip of the buffer tube. Weird problem.

Try pulling the bolt back without the rear takedown pin secured. See if some wiggle room between the upper and the lower receiver allows the bolt to go all the way back. Just be careful since you will have stuff under spring pressure.

 

[VortecK1ng]

I would not cut anything since these parts should all be interchangeable. that will also effect the spring and it may not cycle well when firing. I still suspect the bolt is catching on something on the way back, like the lip of the buffer tube. Weird problem.

Try pulling the bolt back without the rear takedown pin secured. See if some wiggle room between the upper and the lower receiver allows the bolt to go all the way back. Just be careful since you will have stuff under spring pressure.

OK I took the rear one out and tried charging it, it's kinda awkward to watch while I was locking the catch. But it didn't catch, so I turned it around so I could see and tried my hardest racking it and it doesn't look like it making any further progress.

 

[VortecK1ng]

 

[Member 5605]

Stupid question but your carrier slides inside the buffer tube fine right?

 

[VortecK1ng]

I think I found my 3/8th

 

[VortecK1ng]

Stupid question but your carrier slides inside the buffer tube fine right?

Yeah it seems like it does/should the hammer gets in the way.

 

[Member 5605]

I asked because I had an issue with the inside diameter of a follower tube on a rifle and it made a whole mess of problems.

So you are saying that:

A: the other BCG's work fine on this upper/lowers
B: this BCG work on your other upper/lowers​

Have you pulled the bolt face or the cam pin and verified that there isn't extra metal keeping the cam from pulling the bolt face all the way back? Maybe the cam pin hole is drilled in the wrong spot...?

The problem is somewhere simple you will want to slap your momma when you find it.

Try every combination of upper and BCG's, one combo won't work. Then find why. The solution will be obvious.

 

[VortecK1ng]

I asked because I had an issue with the inside diameter of a follower tube on a rifle and it made a whole mess of problems.

So you are saying that:

A: the other BCG's work fine on this upper/lowers
B: this BCG doesn't work on your other upper/lowers​

Have you pulled the bolt face or the cam pin and verified that there isn't extra metal keeping the cam from pulling the bolt face all the way back? Maybe the cam pin hole is drilled in the wrong spot...?

On question a. None of the bcg work on this lower.
And b. All of my BCG's work in my other 2 setups, including the new upper on those other lowers.

No I haven't opened the bcg I guess that is something to look at also I have never opened one but I guess there's always a first time but I think I have isolated the problem away from the bgc the information in the op is not I guess should I say current due to a few posts on here that corrected a few things for me already. I think it has to do with the tube either being too short, or the spring being too long for this particular tube.

 

[bolus]

View attachment 317116 View attachment 317117

I think I found my 3/8th

So that buffer tube is shorter? That would definitely be the cause. that's certainly an easy and inexpensive fix.

weird that there are even different sized buffer tubes.

 

[VortecK1ng]

So that buffer tube is shorter? That would definitely be the cause. that's certainly an easy and inexpensive fix.

weird that there are even different sized buffer tubes.

Well I guess this is a "you get what you paid for" thread haha, 22 bucks I couldn't pass it up! Hah, well I will trim one spiral off the spring and bend it back the way it was and see if I get that 1/8th of an inch clearance that it needs to grab it. I am going to end up sbr'ing this thing so I just wanted a cheap pistol tube for now and that is surely what I got haha. Thanks for the help guys!

 

[Caveman Jim]

Just a thought, if you need to cut the spring to make it work then why not buy a Tubbs flat spiral buffer spring? From what I've found they take up less room in the buffer tube.

Watch the video at the bottom of the page. Hope this helps.

Tubb Precision AR-15 Stainless Steel Buffer Spring (Fits both Carbine and Standard length stocks)

Also, which BT did you buy so I don't buy the same one because I'm looking for a MilSpec BT...

 

[mjbskwim]

So we need a little shorter buffer?