First of all, I always enjoy your posts. I hesitate to comment to someone with your experience, but I ask for my own enlightenment. I would love to know if my extrapolations are correct, or dangerous.

You reported 10gr moving out at 571fps. I use a lot of 4227 in 6 different calibers and immediately thought that was too slow for 10gr.


After checking for 38 special and a 158gr , Hornady Load Center shows 10gr of H4227 hitting 864fps out of a 7.7" barrel using a small pistol primer (wrong primer). That's almost 300fps slower than you achieved with your J frame. Your short snub barrel could account for 150fps or even a little more, but not 300fps.
There is an issue with shooting a slow powder like 4227 out of a short barrel. My expectations could be off because I shoot long barrels almost exclusively. Slow powders need time (in the case and the barrel) to achieve the faster velocities they are known for.

If the above is correct, my first thought was that your crimp might not be adequate to build enough pressure to get that bullet moving.

From your dirty description, we might also surmise that there was incomplete combustion. Most handloaders use Magnum primers for slow powers like H110 and 4227 to get better combustion; and therefore more speed (less dirt). I was shocked to see Hornady even listing non magnum primers.
I would even go so far as to say they are wrong.

Does any of this make any sense?

Prescut