Hello,

Am looking into building a piston-driven AR pistol with pistol-length gas, using a Superlative Arms piston conversion kit.

While researching I have seen that they specify that the "gas port length" (distance from front face of the barrel extension to center of the gas port) needs to be 3.970" or you could bend the piston rod and I've seen some accounts of this out there.

So far I have not found anyone that publishes this dimension in their barrel specs, even among those who have a diagram for their barrel.

For as much as anyone has interest to respond, if you installed a Superlative Arms piston conversion kit on your pistol-length gas barrel and it worked well -- didn't bend the piston rod and you didn't have to modify the piston rod or get them to make you one -- would you mind sharing which barrel manufacturer you used?

This could be good info to have out there for others too, not just me.

Thanks
lwrcdriver

Just talked to Trish at Ballistic Advantage.  She had to check and call me back but she said that is the EXACT measurement they make theirs to.  3.970"