Like the title says.  Also, is the AR15 mid-length tube shorter than an AR10 mid-length gas tube?

the ar10 and ar15 gas tubes are different diameters..not sure about length.

Here's the problem:  This is my first mid-length build.  I installed the barrel, gas block, and gas tube with roll pin.  I then installed the charging handle and finally the bolt/carrier assembly.  The BCA would not go in all the way... the bolt would not go far enough in to the chamber to pass the lug recesses.  I took my factory BM build apart to see how far in to the upper receiver the gas tube extended.  The mid-length tube on my new build goes about 1/2" further than the tube on the factory gun.  I'm trying to see if I have a gas tube of the wrong dimension.

Ok.  Can someone please take a tape measure and measure a spare mid-length gas tube for me?  PLEASE!?!?!?!

@11.5 inches. Sticks through the upper @ 1"

Quoted: @11.5 inches. Sticks through the upper @ 1"

Thanks, Stolat.  The tube I installed measures almost exactly 12" from the gas tube roll pin hole in the gas block to the end of the gas tube that fits in the carrier key.  I must have either a incorrectly manufactured AR15 mid-length tube or an AR10 mid-length tube.

Your barrel nut could be putting sideways pressure on the gas tube. That would cause the carrier to bind.

If it fit in the gas block it's probably the proper sized gas tube.

I just measured mine, and it's 11.5" inches (mid length)

Quoted: Your barrel nut could be putting sideways pressure on the gas tube. That would cause the carrier to bind. If it fit in the gas block it's probably the proper sized gas tube. I just measured mine, and it's 11.5" inches (mid length)

It's definately the length of the tube that is the problem.  I checked my three other AR15 rifles to see how far the gas tube extends in to the upper receiver.  This midlength tube extends at least a half inch further than the others.  This is causing the carrier key to bottom out on the tube, making it impossible for the bolt to fall the last half inch in to the chamber, thus preventing it from going in to battery.  I'm 100% certain the problem is not sideways pressure from the barrel nut.