Today I loaded 6 240gr FNFMJ cartridges with 19.5 gr, 6 with 20gr and 6 with 20.5gr.
Initially I had started loading up 21gr loads but when I compared the level of the powder in the cartridge with the bullet depth needed to reach the crimp cannelure, the powder looked as though it would compress, so I backed it down by 0.5gr.
I fired all six over the chrono
19.5gr: av 1200 ft/s
20gr: av 1171 ft/s
20.5gr: av 1283ft/s
By comparison my 13-odd gr of N350 fired 200gr plated FN bullets at 1100ft/s.
The 20gr result was a bit odd. It had a hi value of 1277 ft/s and a lo value of 1040 ft/s and everything in between, hence the low average.
Based on velocities from a 4" barrel, I'd be tempted to go a bit hight with these bullets, but my only concern is the fact that any more and I think the powder will be compressed and I wouldn't be sure what that might do to the charge...
None of these three showed signs of over pressure. I was checking the primer and case ejection for resistance.
Thoughts on the risk of a compressed load...?