The following are the results shot with the 12 FV 6.5mm Creedmoor in the new Oryx stock in Northern Virginia on Thursday morning, August 22nd at 100 yards. Temperatures were from 75 to 85 degrees with winds from 3 to 5 mph. Altitude of the range is 250 feet above sea level.

During the sessions I interchanged this rifle with my Oryx stocked 12 FV .223 when the barrels in each rifle heated up. I never allowed the barrel temperature to exceed 135 degrees, measured on temperature strips affixed to the barrels of both rifles. The 6.5mm Creedmoor’s barrel temperature would rise from about 85 to 130 degrees after just 5 or 6 shots. The .223’s barrel temperature would rise from 85 to 130 degrees after from 13 to 15 shots.

I used H4350 powder with a three different 130 grain bullets – Sierra TMK #7430, Sierra TGK #4330, and Hornady ELD-M #26177 bullets. All the groups were shot with a NightForce 8-32x56mm Benchrest scope. All rounds were shot using Lapua brass and CCI BR-4 primers. All loads were set up to match the 12th reflection time of 1.361 msec. which should be the ‘sweet spot’ for the 26-inch barrel with a 0.040 recessed crown. The alternative of using a 10th reflection at 1.134 resulted in loads that were well over Pmax and the 14th reflection was flirting with minimum loads. The action screws were torqued to 60 in.-lbs. prior to this session per the Oryx directions.

The load description field shows the powder and charge, the O.A.L., the trim length, and the bullet exit time from the 26-inch barrel.

# Grps. Load Description Bullet Weight Velocity Average Median St Dev 1 2 3 4
3 H4350 41.6 gr 2.892 1.906 wf 1.361 * 75/76 deg. F. 60 in.-lbs. Oryx CCI BR-4 Sierra TMK #7430 130 2724 0.304 0.316 0.032 0.268 0.328 0.376
4 H4350 40.8 gr 2.888 1.902 wf 1.361 * 79/80 deg. F. 60 in.-lbs. Oryx CCI BR-4 Sierra TMK #7430 130 2724 0.319 0.306 0.035 0.293 0.304 0.307 0.370
3 H4350 41.6 gr 2.869 1.900 wf 1.361 * 83/82 deg. F. 60 in.-lbs. Oryx CCI BR-4 Sierra TGK #4330 130 2726 0.328 0.228 0.048 0.281 0.328 0.376
4 H4350 41.4 gr 2.817 1.897 wf 1.361 * 85/85 deg. F. 60 in.-lbs. Oryx CCI BR-4 Hornady ELD-M #26177 130 2719 0.328 0.329 0.027 0.301 0.310 0.347 0.355
14 0.320 0.313 0.032

The combined results for the TMKs averaged 0.312 with a median of 0.307 and the standard deviation was 0.032.
It was coincidence that the TGK and ELD-M bullets both averaged 0.328.
The TGK had one good group and one bad group (one out of group round) around a group that was right on the average.
The ELD-M had a much more consistent group measurements, but the groupings on the target looked a bit more irregular, if that makes any sense.

Only the TMK #7430 bullets have been shot before with IMR4451 powder in the Oryx chassis.

The groups fired with the TGKs and ELD-M bullet with H4350 were 3 and 4 respectively versus the 22 for the TGKs with IMR4451 and 6 for the ELD-Ms with IMR4451. There were 11 groups shot with H4350 with the TMKs so far, versus 29 groups shot with IMR4451.

The difference in sample size makes conclusions very tentative. However, there is a difference even when comparing groups shot with the same NightForce scope and Oryx stock for about the same sample size.

Unfortunately, there were no groups shot with IMR4451 powder with the Oryx stock for the 130 grain TGK or ELD-M bullets. All previous rounds were shot with the factory plastic stock. I think comparisons of H4350 performance with the rounds fired with IMR4451 powder in the Factory plastic chassis probably would be misleading although the average group sizes are larger for the IMR4451 powder averages.
H4350 IMR4451 Diff.
TMK 0.292 0.345 0.053
That amounts to a 15.5% reduction in group size for the H4350 powder compared to the IMR4451 group average.