450 Bushmaster upper not cycling

[Neville]

I recently got a side charging 16 inch 450 Bushmaster upper and installed it on a lower that has worked fine for my 300 blackout uppers. At first I tried with a stiff spring and heavy buffer, gun didnt cycle. It ejects the case and resets the trigger but doesnt get another round or lock back on empty magazine. Changed the buffer to a normal buffer and normal spring, same problem. I removed the gas block and it wasnt mis-aligned and it seems fine, the gas tube is fine, not clogged and goes far enough into the receiver. It seems like its not getting enough gas as far as I can tell since its not locking back. The gun works when you manually cycle rounds through, and locks back on empty mag when manually cycling the bolt. The gas hole is around 0.07 inch. I dont see how an adjustable gas block could help because those just reduce gas, this gun is getting all the gas the gas hole is providing. Should I drill the gas hole bigger or look for some other possible cause? Not sure what to check. Any advice would be appreciated. Thanks

[Narrow_Badger1934]

If it’s BCA like I think it is. Then that’s the problem

[FX4squad]

How did you check your gas block alignment? Sometimes the gas block has to sit slightly off of the barrel collar (idk if that is the right term) for the ports to actually be lined up. The best way to ensure proper alignment is to dimple your barrel.