30tcu Upper

[jacobjrl76]

has anyone ever gotten an ar-15 upper built in a 30 TCU ? Did it work good ?

[Dan Sierpina]

Man, that would almost have no shoulder at all. The big bullet could cause some problems with the mag, unless the front rib is removed. The bullet would also be seated very deeply. I think the 300 Whisper might be a better choice, no fireforming needed, and would probably yield similar velocities. I have one top end in 6mm-223. The 70 grain bullet would take steel over extremely well. Function was as good as a regular .223.

[jacobjrl76]

Man, that would almost have no shoulder at all. The big bullet could cause some problems with the mag, unless the front rib is removed. The bullet would also be seated very deeply. I think the 300 Whisper might be a better choice, no fireforming needed, and would probably yield similar velocities. I have one top end in 6mm-223. The 70 grain bullet would take steel over extremely well. Function was as good as a regular .223.

Did your 6mm-223 make major power factor ? I thought about the whisper was subsonic, I will have to take a look again ! Thanks

[Dan Sierpina]

6-223 does not make major. That was not the reason I did it. The 6mm 70 grain bullet took steel over better than the 22 caliber stuff that was available at the time. The upper is late 80's vintage.