The following are the results shot with the 12 FV 6.5mm Creedmoor in the new Oryx stock in Northern Virginia on Friday and Saturday mornings, September 2nd at 100 yards. Temperatures were from 71 to 79 degrees with winds from 4 to 6 mph. Altitude of the range is 250 feet above sea level.
I decided to test the performance of H4350 powder with 130 grain Sierra TMK #7430, Sierra TGK #4330, Hornady ELD-M #26177 bullets as well as 142 SMK #1742 bullets so I could compare it to previous loads with IMR4451 powder shot in the Oryx Chassis. 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 action screws were torqued to 60 in.-lbs. per the Oryx directions prior to this session.
With the exception of the last two groups, I didn’t allow the barrel temperature to exceed 130 degrees, measured on temperature strips affixed to the barrels of both rifles. I made the exception because I had to shoot the last 8 shots of the last load more quickly than normal to get the load finished before a cease fire was going to be called. Fortunately, the RO gave me a bit of leeway and held up on calling the cease fire until I got the last few shots down range. The barrel temperature was over 140 when I got the final shot down range. With outside temperatures hovering around 70 to 80 degrees F, the 12 FV 6.5mm Creedmoor’s barrel temperature rises from about 85 to 130 degrees with just 10 shots and at over 120 degrees, the POI drops about 0.2 inches lower than when the barrel is cooler.
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 4 IMR4350 41.3 gr 2.850 1.905 wf 1.361 * 71/71 deg. F. 60 in.-lbs. Oryx CCI BR-4 Sierra
130 TMK #7430130 2720 0.345 0.336 0.055 0.299 0.300 0.372 0.410 4 IMR4350 41.3 gr 2.831 1.902 wf 1.361 * 72/73 deg. F. 60 in.-lbs. Oryx CCI BR-4 Sierra 130 TGK #4330 130 2721 0.392 0.398 0.060 0.314 0.385 0.410 0.457 4 H4350 41.4 gr 2.837 1.899 wf 1.361 * 73/76 deg. F. 60 in.-lbs. Oryx CCI BR-4 Sierra 142 SMK #1742 142 2683 0.337 0.314 0.063 0.291 0.308 0.320 0.430 4 H4350 41.4 gr 2.313 1.896 wf 1.361 * 74/79 deg. F. 60 in.-lbs. Oryx CCI BR-4 Hornady ELD-M #26177 130 2721 0.357 0.361 0.033 0.313 0.355 0.367 0.392 16 0.358 0.346 0.059
Today’s session was somewhat sloppy. Somehow, I just didn’t seem to ever get into a groove and had trouble all session with getting comfortable with my set up. There were only two groups (12.5%) that were under 0.3 inches, when I have averaged 23.0% for all the groups shot to date. Also, there were 4 groups (25.0%) over 0.4 inches, more than the 21.6% average to date.
I thought that I was doing OK but when I finished the second load, I could see that I wasn’t shooting as tight groups as I normally do. The TGK hunting bullets usually shoot better than what today’s results show and have averaged 0.347 prior to today’s session.
Part of the impact on the TGK load was caused when the session was interrupted in the middle of the TGK load when the contract mowers arrived to cut the grass on the range. The last two groups of the second load showed the impact of the delay of about 45 minutes while we had to wait for them to finish cutting.
That’s no excuse because I should be able to get back in the groove immediately and not mess up two groups in a row. It just shows how hard it can be some days to keep my concentration. As I get older, it seems to be more difficult to keep my concentration sharp for the two to three hours that I am at the range. I guess at 76, I should just be thankful for being able to shoot at all, but I still want to perform well regardless of how old I get.
The last load was rushed because time was running out and I wanted to finish the last load before the next cease fire and I had almost two groups to go. I let the barrel heat up past what I consider to be a reasonable temperature. I just kept shooting so I could finish in time.
Even then, the last load wasn’t too far off the overall average for 5-round groups of 0.353, but today’s results moved the average up to 0.354. I’ve gotten spoiled by having the average continually drop after every session. Today’s was the first net loss in a long while. It may be that I am now at the point where the average will begin to stabilize.
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