Legionnaire
Contributing Member
I have often shot Federal Gold Medal Match ammo to set a baseline when checking the accuracy of a new rifle. I have had good success when shooting .308. But I was disappointed yesterday. Weather conditions were not great for shooting groups (a bit windy) but I figured I could get sighted in ... and I did.
But the velocity data for the GMM in .260 Rem was weird. I shot a box of 20 using my LabRadar. In that box I had two rounds that clocked well over 3000 fps: 3270 and 3999. With those included in the string, my numbers were:
Average Velocity : 2857
Extreme Spread : 1294
Std Deviation : 292
Excluding the two aberrant shots, the numbers were:
Average Velocity : 2771
Extreme Spread : 102
Std Deviation : 23
That second set looks better, but the ES is still higher than I'd have thought.
I was shooting at a pace of one round every two minutes to avoid overheating the barrel. Temps were in the low 70s, and though the barrel warmed, it never got hot to the touch. Gun and ammo were in the shade the whole time. The first high velocity shot was shot number 6; the second was shot number 18.
Anybody else experienced this? Any possible explanation other than an overcharged or maybe an out-of-spec case? I have on occasion had the LabRadar fail to read a shot, but don't know that I've ever had a significant misread before.
But the velocity data for the GMM in .260 Rem was weird. I shot a box of 20 using my LabRadar. In that box I had two rounds that clocked well over 3000 fps: 3270 and 3999. With those included in the string, my numbers were:
Average Velocity : 2857
Extreme Spread : 1294
Std Deviation : 292
Excluding the two aberrant shots, the numbers were:
Average Velocity : 2771
Extreme Spread : 102
Std Deviation : 23
That second set looks better, but the ES is still higher than I'd have thought.
I was shooting at a pace of one round every two minutes to avoid overheating the barrel. Temps were in the low 70s, and though the barrel warmed, it never got hot to the touch. Gun and ammo were in the shade the whole time. The first high velocity shot was shot number 6; the second was shot number 18.
Anybody else experienced this? Any possible explanation other than an overcharged or maybe an out-of-spec case? I have on occasion had the LabRadar fail to read a shot, but don't know that I've ever had a significant misread before.