Building first ar 15. Piston Driven

[wisdeerkiller]

I am making a wish list on midwayusa.com for building an ar 15 223 bull barrel piston driven. varmint gun.

I picked out the Osprey piston kit. its says max barrel dia is 1" with the barrel I picked is .920 so good there. By brother has already built a piston driven ar but not a bull barrel or tubular free float rail.

so with that he's not sure if that rail will work with the piston.

Is there any reason why this won't work or anything we're missing?

I should also note I am building everything from parts. (no complete upper or lower)

Thanks