Hey all,
Went out today to put some 7x57 loads over the chrony and decided to do some Norinco 7.62x51 as well.
I shot the Nork ammo out of my FR7 (18" barrel)
Average: 2696 fps
Extreme spread: 74 fps
Average deviation: 23.7
I had chronographed the same ammo out of my M-305 (22" barrel) last year and average speed was 2795 fps
Equals a loss of 99 fps for 4" difference of barrel length.
I actually thought there would be more of a difference.
I think that the "Norinco Flyer" we all experience could be the ammo. I shot one group that had 4 shots in less than 2" with the last shot opening the group to over 3.5".
ps: 7x57 loads with IMR 7828 and Speer 175 Mag Tip bullets chronographed at 2423 fps. Average group size about 1.25", 1 group was 5/8"
Went out today to put some 7x57 loads over the chrony and decided to do some Norinco 7.62x51 as well.
I shot the Nork ammo out of my FR7 (18" barrel)
Average: 2696 fps
Extreme spread: 74 fps
Average deviation: 23.7
I had chronographed the same ammo out of my M-305 (22" barrel) last year and average speed was 2795 fps
Equals a loss of 99 fps for 4" difference of barrel length.
I actually thought there would be more of a difference.
I think that the "Norinco Flyer" we all experience could be the ammo. I shot one group that had 4 shots in less than 2" with the last shot opening the group to over 3.5".
ps: 7x57 loads with IMR 7828 and Speer 175 Mag Tip bullets chronographed at 2423 fps. Average group size about 1.25", 1 group was 5/8"