Smith & Wesson 610-3 to 10mm magnum

[Bimmer]

Another update...  I shot my 10mm Mag, again. 

I tried 16, 17, and 18gr of 2400, and didn't have any cases split or other problems. 

I think I remember that when I shot the 18gr last time, I had difficulty chambering the moon clipped rounds, and then found a piece of copper shaving in one cylinder...  Maybe it's possible that one ill-fitting round caused the split case? 

[sparkyv]

How were the velocities the 2nd go-round, Bimmer?

[Bimmer]

Velocities were about the same... 

I loaded a big batch with 16.5gr, and I put a touch of crimp on the cases after seating, so that the mouths measured 0.421" or so.  (That's about the same as factory .40/10mm.) 

The crimp didn't seem to make much difference in terms of velocity or SD. 

Having fired 10+ rounds of each: 

16.0 = 1,081Avg.,  34SD

16.5 (crimped) = 1,141Avg., 48SD

17.0 =  1,159Avg., 19SD

18.0 (only 6 rounds) = 1,193Avg., 50SD. 


Looking at these numbers 17 grains seemed like a sweet spot (low SD, good velocity).  Eighteen grains seems compressed, and SDs were too much, and all for only 34fps more. 

So, I loaded up another 300 rounds with 17 grains, and now I have a decent supply of ammo. 


Now I'm going back to loading .40S&W for my Glocks and .30 Mauser for my uncle's Broomhandle...