06-02-2012, 04:39 PM
I wouldn't claim to know all there is to be known about gas blocks but I have some experience and some observations. I think I've built around 20 uppers or so now, about half in 6.5 and the other half various calibers mostly .223. l've used both steel and aluminum, set screw, clamp on, bedded and not. I haven't seen much difference in any of the combinations. However, I've seen some negative impacts on accuracy in how the gas tube is set up.
The gas block must be in a vertical position that centers the gas tube in a torque free path through the barrel nut and receiver key way. If this is not done it will impart variable harmonic influence on the barrel. The proper way to do this is to mount the gas block dry, insert the tube in the gas block tenon but without the roll pin installed and sweep it back and forth above the action. Observe the swing to either side of the center line of the action and adjust the gas block so there is equal swing on either side.
By correcting this gas tube alignment I've turned 1.5 MOA guns into .5 MOA guns.
Bob
The gas block must be in a vertical position that centers the gas tube in a torque free path through the barrel nut and receiver key way. If this is not done it will impart variable harmonic influence on the barrel. The proper way to do this is to mount the gas block dry, insert the tube in the gas block tenon but without the roll pin installed and sweep it back and forth above the action. Observe the swing to either side of the center line of the action and adjust the gas block so there is equal swing on either side.
By correcting this gas tube alignment I've turned 1.5 MOA guns into .5 MOA guns.
Bob