I loaded up some rounds using H110 and the above data, substituting the Montana Gold 250gr for the Hornaday 250gr SST. I didn’t crony them, I just wanted to see what kind of groups I’d get. 1.5″ with the Hornaday 240gr and 2.25″ with the Montana Gold bullets. 100yrds.
I’m not sure on the Point of impact, this go ’round I didn’t shoot any factory rounds, I just shot a bunch with the 39.3 gr load and the bullets seated at 2”, 2.05″. 2.1″ and 2.15″. The 2.05″ seemed the best group and each length had a different point of impact.
As a side note, and it will be interesting to see how it compares, but I’m finally getting some nice 1″ ‘ish groups at 100 yrds with the Montana Gold bullets using 39.3 grs of H110 and an OAL of 2.05″.
Is the bolt holding open on those 43 grainers now? Make sure that you single load with the mag inserted until you get your head around your situation.
I sure do not see any excessive pressure signs at all. I’d, with caution, suggest an increase in powder (h110) watch for excessive pressure signs and you make the call, in relation to safety. I think you’ll end up in the 2500fps+ arena, which is 3500ft/lbs and with a 200yd zero, is 100% hits at 300yds (on a 8″ paper plate), assuming you get the groups down a little. This blows the doors off the other big bore AR’s and you haven’t gotten to AA1680 yet, which will yield 200fps+ more than you are now getting with the same pressures. Note- Someting to consider, in extreme cold weather (zero or lower) the 296 will ignite better.
I plan to call Montana Gold and talk to their engineer and asertain how thick those 250 jackets are, if they are in fact thick enough, these may end up being the new gold standard.
The following are five rounds of each load at 100 yrds using Montana Gold .452 250 gr FP bullets and H110 powder with an OAL of 2.15″.
load velocity group
Factory 2150 fps 1.24”
38.5 grs 2045 fps 1.35”
39 grs 2095 fps 2.79”
40 grs 2135 fps 2.13”
41 grs 2235 fps 2.65”
41.5 grs 2305 fps 4.95”
42 grs 2346 fps 2.74”
42.5 grs 2310 fps 2.34”
43 grs 2350 fps 3.83”