Carrier group/ Buffer Tube problems with AR 15

[BADUNAME51]

First post--newbie here.

I am having issues with my m4. I have a yankee hill free float upper on a rock river lower. I built it myself and have been running it for a year with no problems. Eats any ammo and as fast as you can squeeze she talks. That being said. I noticed the other day the buffer tube/stock was loose. I tightened it back up and shot a few rounds and the bolt siezed back in the tube. I disassembled it and took the buffer tube off, put everything back together and now the bolt will not go all the way back to engage the bolt stop. Manually when pulling the charging handle it stops with about 1/8" to 1/4" to go in order for it to clear the bolt catch. I cant back the tube off anymore because as it sits its on the edge of the buffer stop

any suggestions before i buy a new tube/buffer/spring

also the upper works fine when i put it on any of my other lowers, and previously worked fine on this one

thanks

 

[Z-Michigan]

Is it possible that something is stuck in the buffer tube?

What condition is the buffer in? Any visible damage?

 

[BADUNAME51]

nothing in the tube, and it looks fine, no damage what so ever

i am perplexed. i have built many M4's for both work and play and never been unable to chase down a problem. i am at a loss with this one

 

[hals1]

Try M4Carbine.net. I already started a thread in Technical Discussion titled "Ran across this on The Highroad". They will probably ask for pictures.
When you get it running again, stake the castle nut and nothing will loosen up again.

 

[TonyAngel]

If it was running right before you removed the buffer tube, but is now not running right after re-installing it, my knee jerk would be that you messed up the buffer tube when you re-installed it.

When you re-installed the tube, did you try to stake the nut so that it wouldn't come loose again? If so, did you put the lower in a proper fixture to do it or did you just lay the assembly on a bench and hit it with a hammer and chisel? Or maybe stake the nut with the tube in the vice rather than the receiver? I'm asking because it sounds to me like you bent your buffer tube.

I'd remove the lower from the upper. Install the spring and buffer and see if you can manually compress the buffer with a dowl of some sort and see if it binds. If it does, something is amiss with either the tube or the buffer. If it doesn't, look at the bolt/trigger assembly.

 

[BADUNAME51]

I didnt stake it at all, never used a chisel on any gun (not one that i wanted to actually work anyway). And yes i have and use the proper reciever vice and tools on all my M4's. so i was at a loss, however, like suggested the only thing i could think would cause this was a bent tube. That has to be it. I spoke with my roommate who said that he did drop it and it landed awkard on the stock when moving some things around in the safe.. he didnt think it did any damage and put it back in there. However it has to have been bent, its not noticible when looking at it, but there is no other explanation

Good call on the Bent buffer tube

 

[kwelz]

A tube should not bend. Was it a commercial tube or mil spec?

 

[Zak Smith]

1. Are you sure you didn't have a rifle buffer sitting around and mistakenly put that one in?

2. Are you sure the buffer retaining pin/spring are installed correctly?

ETA.

3. If you remove the spring and buffer, and reassemble the rifle, can you retract the BCG all the way?

 

[BADUNAME51]

Tube was comm. and yep, it was bent. ever so slightly on the end. the bolt would not go all the way back with spring/buffer removed, Took the tube off and dropped the bolt into the empty tube, it lacked about a 1/4" I held it up to the light and turned it and could notice a slight bend about and inch from the end.

in any case, i put a brand new tube on and reassembled and it works fine

never seen that one.

thanks for all the input guys