Over the last year or so I built a AR260 to compliment my match 260.
Mega matched upper and lower (nickel boron)
RWS ss 20" spiral fluted heavy barrel
Troy 13" handgaurd and battle ax stock
JP trigger, bolt and muzzle eliminator
DPMS carrier
In other words, I didn't skimp on any of the parts.
In an attempt to tighten my group and get a load for the gun I have noticed that I have vertical drift. This is where I need help. I have increased powder in .2 increments from 38G to 41.5G (max is 40.8 in the sierra manual)with the same results. first shot is dead on.2-5 are about 2" low with a heated barrel. This leads me to believe it is barrel harmonics vs. the charge, but since I don't have the answer I could be wrong..
I'm using H4350 with sierra matchking 140's and once fired federal 308 brass necked and sized.
I have checked for anything loose on the gun and even took the muzzle break off with the same result. Its fired from a bench using a front and rear bag.
Any help would be appreciated. I also realized that I shouldn't expect the same accuracy as my "big" 260 with the semi auto but I should be doing a lot better than I am: (Surgeon action, bartlien 26" HV, Jewell, AI chassis w/ viperskins)
Anyone else have a similar rifle (20" 260) and if so, what is your powder charge?
thanks
Mega matched upper and lower (nickel boron)
RWS ss 20" spiral fluted heavy barrel
Troy 13" handgaurd and battle ax stock
JP trigger, bolt and muzzle eliminator
DPMS carrier
In other words, I didn't skimp on any of the parts.
In an attempt to tighten my group and get a load for the gun I have noticed that I have vertical drift. This is where I need help. I have increased powder in .2 increments from 38G to 41.5G (max is 40.8 in the sierra manual)with the same results. first shot is dead on.2-5 are about 2" low with a heated barrel. This leads me to believe it is barrel harmonics vs. the charge, but since I don't have the answer I could be wrong..
I'm using H4350 with sierra matchking 140's and once fired federal 308 brass necked and sized.
I have checked for anything loose on the gun and even took the muzzle break off with the same result. Its fired from a bench using a front and rear bag.
Any help would be appreciated. I also realized that I shouldn't expect the same accuracy as my "big" 260 with the semi auto but I should be doing a lot better than I am: (Surgeon action, bartlien 26" HV, Jewell, AI chassis w/ viperskins)
Anyone else have a similar rifle (20" 260) and if so, what is your powder charge?
thanks
