Ar-15 300-221 Sbr

[pud-knocker]

I have a couple of the carbine length adjustable gas tubes, had problems with both after about 30 rounds....the pinned on block came loose to the point that the pin came out and the block rolls around on the tube....don't recommend them to anyone....

I use the adjustable PRI, JP, and un-adjustable Vltor in the pistol position....have had good results with all three....