Guy B. Meredith
New member
Since I will be focusing on my new M66 4" I decided to check out the performance of a couple of loads.
!* WARNING--THESE LOADS ARE IN EXCESS OF LISTED SAFE LOADS AND SHOULD NOT BE USED IN YOUR FIREARM! WARNING *!
At one time I had been loading my .38 spl with 4.8 gr AA#2 under a WCB copper plated 158 gr bullet with WSP primer. In my 6" 686+ and even the 5" 627 the velocity ran in the order of 850 fps and SD under 20. I experimented with roll crimp and taper crimp with minimal differences. Other shooters had been using 4.6 gr for the same performance.
I then decided to try 6.4 gr AA#5 with the same bullet and primer to work for lighter recoil and followup recovery for competition. The AA#5 load gives about 850 fps out of the 686+ and 627 with a SD of around 26.
I decided to go back for a look at the AA#2 load as AA#5 is more expensive than AA#2 and with the thought that the higher volume for AA#2 may provide for better ignition and more consistent performance. Don't know why I thought the last as I had not observed that in the past.
Firing the M66 over the Shooting Chrony I get the following with the AA#5 load over two strings:
Average velocity 874.1 862.0
Extreme spread 75.98 85.71
Standard deviation 29.71 25.11
But the AA#2 load is something again. Out of the 4" barrel it gives:
Average velocity 903.5 899.0
Extreme spread 21.99 26.40
Standard deviation 7.14 8.00
What the heck??
I have been playing around with the crimp setting and decided to remain with roll crimp set to the point that there is some evidence of crease in the copper plating in the cannalure and on the verge of mid case crumble. (I WILL be setting up for separate dies to avoid case crumble!!) This did not appear to affect the AA#5 load so does not seem to explain the AA#2 performance.
!* WARNING--THESE LOADS ARE IN EXCESS OF LISTED SAFE LOADS AND SHOULD NOT BE USED IN YOUR FIREARM! WARNING *!
At one time I had been loading my .38 spl with 4.8 gr AA#2 under a WCB copper plated 158 gr bullet with WSP primer. In my 6" 686+ and even the 5" 627 the velocity ran in the order of 850 fps and SD under 20. I experimented with roll crimp and taper crimp with minimal differences. Other shooters had been using 4.6 gr for the same performance.
I then decided to try 6.4 gr AA#5 with the same bullet and primer to work for lighter recoil and followup recovery for competition. The AA#5 load gives about 850 fps out of the 686+ and 627 with a SD of around 26.
I decided to go back for a look at the AA#2 load as AA#5 is more expensive than AA#2 and with the thought that the higher volume for AA#2 may provide for better ignition and more consistent performance. Don't know why I thought the last as I had not observed that in the past.
Firing the M66 over the Shooting Chrony I get the following with the AA#5 load over two strings:
Average velocity 874.1 862.0
Extreme spread 75.98 85.71
Standard deviation 29.71 25.11
But the AA#2 load is something again. Out of the 4" barrel it gives:
Average velocity 903.5 899.0
Extreme spread 21.99 26.40
Standard deviation 7.14 8.00
What the heck??
I have been playing around with the crimp setting and decided to remain with roll crimp set to the point that there is some evidence of crease in the copper plating in the cannalure and on the verge of mid case crumble. (I WILL be setting up for separate dies to avoid case crumble!!) This did not appear to affect the AA#5 load so does not seem to explain the AA#2 performance.