It's been quite a while since I have checked in and almost as long since I have built an AR but the bug is back and it has bit me hard!

I want to build a mid length 6.5 grendal with a gas piston operated upper.  Can anyone point me to a thread or tell me where I can get the parts to make this happen?

I have never built a gas piston upper so I am not sure what the differnces are, i.e. dont know what to buy that would be gas piston specific.  Combined with a caliber I have never built I am a little daunted before I get started.

Thanks for any and all help.

Building a rifle in a caliber designed for long range accuracy, with a piston system that will undoubtedly degrade long range accuracy?

I am not really in it for long range accuracy but I didn't realize that manipulating the force used to extract the empty cartridge affected the accuracy.   Can anyone tell me if I buy a Grendel bolt and barrel and bushmaster gas piston conversion kit will I have a functional weapon?

When you have a mass (the piston/op rod/etc) moving parallel to the bore, it will affect accuracy in some (even if small) way. It sure made a huge difference with my lightweight AR.

I don't believe Bushmaster makes a midlength piston kit, they use the Ares carbine kit, it will probably function just fine, but I don't see the point.

You might consider reading my Ares gas piston review...

www.ar15.com/forums/topic.html?b=3&f=118&t=380245

AA makes a 14.5" M4 profiled barrel with an extended flash hider.  That barrel uses a carbine length gas tube.  You could install an Ares kit in that 6.5 upper.

Scott

I have never seen a mid-length piston kit before.  Not sure anyone makes one at this time.

It might be nice to have an adjustable gas system since the pressure curve of the Grendel will be different than 5.56.  You don''t want to beat the gun to death!