Finally got to the range with some 60 grain TMK loads for my Les Baer Super Varmint .223 with a 1:8 twist, 18-inch, 416R stainless steel barrel with a Bushnell 6500 Elite 4.5-30x50mm scope at 100 yards.
Here are the results for 3 5-round groups with 3 different loads.
I used H4895 powder all with the same charge but varied seating depth to get the same bullet velocity (also barrel exit time) given slightly different trim lengths in the brass I used and based upon the forecasted rising temperatures.
The perfect exit time would have been 1.0493, but given the temperature at the time I shot was a few degrees off what I loaded for so the exit time was 0.0013 msec. off.
The velocity was close enough to have the blast reflection just about at the bolt face so the barrel crown was the tightest when the bullet exited.
# Groups Hand Load data
Lapua Brass, CCI BR-4 primers, exit time 1.048 msec.
Powder, Charge, O.A.L., bullet, velocity, trim length, temp		 Bullet Bullet Weight (Grains) Velocity FPS Group (in.) 3-Shots % Minutes of Angle Avg Group (in.) 5 shots % Minutes of Angle # Groups Mean Std Dev Grp 1 Grp 2 Grp 3
3 H4895 24.6 gr 2.330 O.A.L. 60 TMK 3132 case 1.758 51/47 deg F. Sierra Tipped Match King #7160 60 3132 0.208 19.9% 0.309 29.5% 3 0.329 0.093 0.208 0.329 0.390
3 H4895 24.6 gr 2.331 O.A.L. 60 TMK 3132 case 1.755 53/49 deg F. Sierra Tipped Match King #7160 60 3132 0.293 28.0% 0.347 33.1% 3 0.316 0.075 0.293 0.316 0.432
3 H4895 24.6 gr 2.333 O.A.L. 60 TMK 3132 case 1.758 53/50 deg F. Sierra Tipped Match King #7160 60 3132 0.303 28.9% 0.388 37.1% 3 0.356 0.105 0.303 0.356 0.506
Winds were dead calm for the first load and rose slightly as the temperature rose. However, I rushed shooting the last group in the last load to get the group in before a scheduled cease fire.
Even then, the average group sizes were pretty close and the overall average was 0.348 for 9 groups.