sungazer wrote:The idea is to get your ES or SD (both related) down to a minimum. That way you get less deviation in elevation if you are doing everything else right as well.
sungazer Nailed it...
The goal is to minimise as much as possible the variations in velocity from the first round till the last.
This is the data captured by my LabRadar at Plinkfest 2017 using the BR50 BFG firing "Match" prepared Lapua brass then precision reloaded. As a estimate it took approx. 1 hour per round from start to finish to prepare and load.
Cases were all +/- 0.2gr
Projectile = Classified Brass VLD
Weight = Approx 800gr
Not bad (-2.5gr from best)
AR2218 215.0gr
Series No 1
Total number of shots 5
Stats - Average 2576.84 fps
Stats - Highest 2592.83 fps
Stats - Lowest 2571.65 fps
Stats - Ext. Spread 21.18 fps
Stats - Std. Dev 9 fps
AR2218 217.5gr - Best result and smack on a node and subsequent testing has yielded very similar or better numbers.
Series No 2
Total number of shots 5
Stats - Average 2601.5 fps
Stats - Highest 2604.52 fps
Stats - Lowest 2597.76 fps
Stats - Ext. Spread 6.76 fps
Stats - Std. Dev 2.63 fps
Worst (+2.5 grain from best)
AR2218 220.0gr
Series No 3
Total number of shots 5
Stats - Average 2646.52 fps
Stats - Highest 2684.56 fps
Stats - Lowest 2633.01 fps
Stats - Ext. Spread 51.55 fps
Stats - Std. Dev 21.82 fps
Getting closer to next node but also approaching max case capacity, although no signs of excess pressure noted. Might push the limit a bit in the future.
AR2218 222.5gr
Series No 4
Total number of shots 5
Stats - Average 2660.52 fps
Stats - Highest 2671.32 fps
Stats - Lowest 2650.8 fps
Stats - Ext. Spread 20.51 fps
Stats - Std. Dev 7.59 fps
AR2218 225.0gr
Series No 5
Total number of shots 5
Stats - Average 2690.25 fps
Stats - Highest 2700.08 fps
Stats - Lowest 2679.63 fps
Stats - Ext. Spread 20.45 fps
Stats - Std. Dev 8.19 fps