What the F**K!!

[jscwerve]

Finally got my upper today, mounted on my lower, placed empty mag in, pull charging handle back, and bolt catch doesn't catch. I pull the buffer spring out, buffer, measure both, both are in spec exactly with mil spec carbine length. Outside of tube length is right on for mil spec tube. The INSIDE on the other hand is not long enough!!! The end cap of the damned tube is like 1/2" thick!! the buffer spring, bolt, and buffer do not go in far enough. Rifle cycles ammo, and I'm sure it will fire, but this is a load of crap. Now I need a new buffer tube that is made properly.

[Quib]

That's pretty crazy.

Good catch though, and good troubleshooting! I can see a problem like that stumping quite a few folks! Who would think to check the interior depth of the rec. extension.

I have seen a similar problem where a plastic bag was shoved down inside the rec. extension, causing the same malfunction.

[SAnd]

A few months ago I discovered that while working on another project.

I have a Armalite 6 position butt stock that the buffer/spring hole is 7 3/4 inches deep and has a square bottom.

I also have a Tapco 6 position butt stock that the buffer/spring hole is 6 13./16 inches deep at the edge. The bottom of the hole is angled from the drill bit. They didn't square it off.

All the external dimensions are the same.

That's 15/16 of an inch difference.

[jscwerve]

Got it fixed. Noticed it only really needed to go about 1/16" furthur for the catch to work. I took out the buffer and filed off 1/8" from the poly end of it. Works like a champ now. Didn't figure a couple of grams of weight lost wouldn't make much of a difference.

[ChunkyMonkey]

Couldnt you cut a coil of the buffer spring?

[jscwerve]

Couldnt you cut a coil of the buffer spring?

No, I took the spring and buffer out, and the spring was able to compress completely on the buffer, so it wasn't taking up any extra space. The spring also measured in spec with proper length.