Gents,
I've got a DPMS 308 that I don't think is quite right yet. In the interest of disclosure, the rifle is as follows:
-1/10 24" SS
-Standard DPMS tube FF HG (and the barrel nut is now properly torqued)
-CMMG lower, RRA 2 stage non adjustable trigger/hammer, A2 buttstock w/extender
-Bushnell 4200 FFP 3-12 in an extended GGG mount
-JP adjustable gas block
Had it out some time ago and was shooting ~150 gr Federal something through it (FMJ) so I know that's probably optimal for the twist rate, HOWEVER the rifle was putting down pretty crappy groups in semi (from bags). I tightened down the setscrew fully on the JP block to shut the gas off and the groups tightened significantly, to say ~1.5".
When in semi I seemed to be chasing the thing around a bit, and it seems that the gas adjustment was moving around.
Have any of you guys had problems similar to this?
Within a window of a normally functioning rifle, how sensitive is grouping to the gas adjustment on the block? What increment of adjustment seems meaningful?
While the JP block does seem to adjust gas well enough, I would describe the arrangement of holding that adjustment as piss poor to non-existent. What do you guys do to alleviate that?
I've got a DPMS 308 that I don't think is quite right yet. In the interest of disclosure, the rifle is as follows:
-1/10 24" SS
-Standard DPMS tube FF HG (and the barrel nut is now properly torqued)
-CMMG lower, RRA 2 stage non adjustable trigger/hammer, A2 buttstock w/extender
-Bushnell 4200 FFP 3-12 in an extended GGG mount
-JP adjustable gas block
Had it out some time ago and was shooting ~150 gr Federal something through it (FMJ) so I know that's probably optimal for the twist rate, HOWEVER the rifle was putting down pretty crappy groups in semi (from bags). I tightened down the setscrew fully on the JP block to shut the gas off and the groups tightened significantly, to say ~1.5".
When in semi I seemed to be chasing the thing around a bit, and it seems that the gas adjustment was moving around.
Have any of you guys had problems similar to this?
Within a window of a normally functioning rifle, how sensitive is grouping to the gas adjustment on the block? What increment of adjustment seems meaningful?
While the JP block does seem to adjust gas well enough, I would describe the arrangement of holding that adjustment as piss poor to non-existent. What do you guys do to alleviate that?