11-21-2013, 03:29 AM
I'm one of the unlucky ones that got an ARS barrel from Midway with a short chamber and YES it is marked 6.5 Grendel on the barrel. Other than testing it out before buying (not possible at any store I know of) we as consumers rely on the honesty of the manufacturers. Unfortunately this didn't pan out in my case. My suspicion is that since I got it right after the rights were released from AA, that whomever made it was still using the old non SAAMI chamber specs but stamped it Grendel anyway.
So, the solution? I rented a PTG uni-throater reamer from 4-D rentals in MT. The big advantage of this PTG reamer is that you can use it while the barrel is still installed on the upper! No need to disassemble the entire rifle. It was very easy to use and adjust. I wanted to load Nosler BT's out to mag length, so I adjusted the reamer a turn at a time until the 100 gr and 120 gr BT's touched the lands at 2.285" COAL.
Here are the before and after COAL's (to kiss the lands) for some bullets I've been using.
Before - After
100 gr Hornady Interlock SP = 2.120" - 2.237"
100 gr Hornady Amax = 2.150" - 2.240"
100 gr Nosler BT = 2.220" - 2.285"
120 gr Nosler BT = 2.220" - 2.285"
123 gr Hornady Amax = 2.225" - 2.320"
Some may say that reaming out the troat with a uni-throater would do away with the Grendel's compound throat thus decreasing it's inhearant accuracy. I am under the impression that if these ARS barrel chambers weren't cut to the proper depth, they probably didn't have the compound throat either.
In summary, I am very happy with the results. I can now load all bullets to at least published COAL's and I actually saw an improvement in accuracy overall by about .3 MOA over all loads tested.
So, the solution? I rented a PTG uni-throater reamer from 4-D rentals in MT. The big advantage of this PTG reamer is that you can use it while the barrel is still installed on the upper! No need to disassemble the entire rifle. It was very easy to use and adjust. I wanted to load Nosler BT's out to mag length, so I adjusted the reamer a turn at a time until the 100 gr and 120 gr BT's touched the lands at 2.285" COAL.
Here are the before and after COAL's (to kiss the lands) for some bullets I've been using.
Before - After
100 gr Hornady Interlock SP = 2.120" - 2.237"
100 gr Hornady Amax = 2.150" - 2.240"
100 gr Nosler BT = 2.220" - 2.285"
120 gr Nosler BT = 2.220" - 2.285"
123 gr Hornady Amax = 2.225" - 2.320"
Some may say that reaming out the troat with a uni-throater would do away with the Grendel's compound throat thus decreasing it's inhearant accuracy. I am under the impression that if these ARS barrel chambers weren't cut to the proper depth, they probably didn't have the compound throat either.
In summary, I am very happy with the results. I can now load all bullets to at least published COAL's and I actually saw an improvement in accuracy overall by about .3 MOA over all loads tested.