I recently acquired a 12.5" MGM barrel in 6.8 rem that was nearly new. It was originally ordered from MGM by another member here, he didn't have time to practice with it so he sold it after firing only 20 rounds, the guy he sold it to changed the scope base and then sold it to me after having it for about 2 weeks(said he didn't shoot it because he couldn't find any good factory ammo). I learned the history of the barrel after it was paid for but I was concerned that the barrel was a poor shooter since 2 people dumped it in short order. I have been anxious to get out and shoot this to see if in fact it was a poor shooter, the rain finally let up enough for me to get out yesterday.
In my haste to place a powder order I didn't realize I was out of 322, so the loads I tested were all over AA 2230-c. 2230-c is a discontinued data powder that is slower than 2230 but slightly faster than 2460. So my disclaimer " there is no published data for 2230-c, or for some of the bullets I tested so if you attempt to duplicate any of these loads do so at your own risk".
The first load I tested was a 110 v-max over various charges of 2230-c (28-29.5 gr in .5's). I got the gun on paper at 50 yards then shot a 3 shot 1.5" group with the 28 gr load. Then I moved to 100 where I got 1.5-1.8" groups with each load with the 110 vmax. I was starting to think the barrel was not going to be a shooter, I expected better than 1.5" with the vmax.
I then tested 130 sst over 25-26 grs 2230-c. I was surprised to see my first group (25 gr) go sub-moa (0.8"), as the powder went up so did the group size at 25.5 gr I got just about 1" and 26 grains got me 1.25". One thing to note here is that the OAL for this 130sst load was 2.340 well above the max published oal of 2.260. This load obviously would not work in a clip fed gun, and may not be safe in other single shots due to the close proximity of the bullet to the lands. My barrel seems to be long throated and that may be why the longer bullet did better (seated out farther).
Next was sierra 110 (#1810)and 130 (#1830) pro hunters. Here I found the sweet spot for this barrel. Every load I tested with either sierra bullet went sub-moa. The best load for the 110 turned out to be 28.5 grains 2230-c with a oal of 2.260 it went 0.38 for 3 shots at 100. The best load for the 130 was 25.5 gr 2230-c with an oal of 2.315 (again this is longer than published max), it went .45 for 3 shots at 100. My fears about the barrel were erased at this point.
Next I tested some hornady 130 interlocked sp's over 25-26 gr 2230-c. The best load was 25 gr of powder and an oal of 2.305 which produced a 5 shot group of .77 at 100 yds. The 25.5 gr load shot just under 1" and the 26 gr load shot 1.2".
The last 2 bullets were 100 gr sp's a hornady and a rem bulk bullet. The hornady shot just under 1" with 29 gr 2230-c but opened up to 1.4-1.7" with all other powder charges oal was 2.240. The rem bulk bullet shot about 1.5" with every powder charge and an oal of 2.20".
Over all I am happy with the results. I think I will go back and seat some of the shorter bullets a little closer to the lands to see if I can shrink groups some. I also have a couple boxes of factory ammo to shoot and about 3 other loads I didn't get to yesterday.
