The gas tube pin is a roll pin. The osprey one is a solid steel pin. I bend one trying to put it in. Thanks goodness osprey kit comes with 2 pins, The second pin I started from the left side instead, and had to hammer it really hard. TripleBravo did a review here, but since the osprey forum went away you can't find it anymore
http://www.weaponevolution.com/forum/showthread.php?2287-Osprey-Defense-OPS-416-piston-retrofit-kit
He used 2 kits, the old one and the new one. I have the new one, and works like a clock. As always I recomend my friend an Osprey Kit for non-freefloat barrels, and AA for freefloat ones