MikeDeltaFoxtrot
AH veteran
- Joined
- Nov 30, 2017
- Messages
- 137
- Reaction score
- 149
- Location
- Virginia, USA
- Media
- 24
- Member of
- SCI, NRA
- Hunted
- USA (Alaska, Florida, North Carolina, Virginia), South Africa
Hello: I am preparing for my first African hunting trip. I'll be hunting plains game in the Eastern Cape province of the RSA this coming June. My primary rifle for the trip will be a Winchester M70 Super Grade chambered in .300 Win Mag, topped with a Leupold VX 3i 4.5-14 x40 in Warne rings and bases.
I am developing a load using Barnes 180 gr. TSX bullets and IMR 4350 powder. My goal is 3000 fps and sub-MOA groups off the bench. I have the velocity nailed with 69.3 grains (the max load out of the Barnes manual), but I am not presently satisfied with the accuracy of the load. My groups are averaging 2.3" at 100 yards. Here is the data I have collected. During both ranges session so, far, the air temperature was about 27 degrees Fahrenheit. The velocity numbers are based on a 10 round average for each load.
Day 1
66.0 grains = 2931 fps
67.0 grains = 2880 fps
Day 2
68.0 grains = 2844 fps
68.5 grains = 2888 fps
69.0 grains = 2984 fps
69.3 grains = 3009 fps
I didn't really measures group size the first day, but for the second set up loads, group sizes at 100 yards were as follows:
68.0 grains: 2.137", 2.553"
68.5 grains: 2.830", 1.780"
69.0 grains: 3.990", 1.774"
69.3 grains: 2.229", 1.768"
Average group size across all 8 groups is 2.38". All the loads except the 69.3 were seated to 3.340", which is what it says in the Barnes manual. For the 69.3 loads, I measured the chamber with the Hornady gauge and seated .050" off the lands for a OAL of 3.427". Those rounds are too long to fit in the magazine, and there doesn't seem to be much difference in accuracy.
I am wondering what I can do to improve the accuracy of my loads at this point. In excess of 2 MOA is not acceptable. For testing, the gun is sandbagged in place on a benchrest. I shoot an average of .6" groups from the same set up with my Remington 700 Varmint in .308, using Sierra MatchKing bullets, it it isn't me.
Do I need to try a different powder? Should I continue experimenting with the seating depth?
Any help is much appreciated.
I am developing a load using Barnes 180 gr. TSX bullets and IMR 4350 powder. My goal is 3000 fps and sub-MOA groups off the bench. I have the velocity nailed with 69.3 grains (the max load out of the Barnes manual), but I am not presently satisfied with the accuracy of the load. My groups are averaging 2.3" at 100 yards. Here is the data I have collected. During both ranges session so, far, the air temperature was about 27 degrees Fahrenheit. The velocity numbers are based on a 10 round average for each load.
Day 1
66.0 grains = 2931 fps
67.0 grains = 2880 fps
Day 2
68.0 grains = 2844 fps
68.5 grains = 2888 fps
69.0 grains = 2984 fps
69.3 grains = 3009 fps
I didn't really measures group size the first day, but for the second set up loads, group sizes at 100 yards were as follows:
68.0 grains: 2.137", 2.553"
68.5 grains: 2.830", 1.780"
69.0 grains: 3.990", 1.774"
69.3 grains: 2.229", 1.768"
Average group size across all 8 groups is 2.38". All the loads except the 69.3 were seated to 3.340", which is what it says in the Barnes manual. For the 69.3 loads, I measured the chamber with the Hornady gauge and seated .050" off the lands for a OAL of 3.427". Those rounds are too long to fit in the magazine, and there doesn't seem to be much difference in accuracy.
I am wondering what I can do to improve the accuracy of my loads at this point. In excess of 2 MOA is not acceptable. For testing, the gun is sandbagged in place on a benchrest. I shoot an average of .6" groups from the same set up with my Remington 700 Varmint in .308, using Sierra MatchKing bullets, it it isn't me.
Do I need to try a different powder? Should I continue experimenting with the seating depth?
Any help is much appreciated.