Chrono results: 15.4gr of 2400 behind 158gr copper plated flat nose, S&W 686 6"

[DarkSkyx]

Chrono results: 15.4gr of 2400 behind 158gr copper plated flat nose, S&W 686 6"

Temp: 27C

Smith & Wesson 686, 6" barrel

Winchester small pistol magnum primers

FPS:

1156
1270
1221
1208
1189
1134
1119
1167
1159
1154
1194

2nd group:

1210
1222
1197
1129
1170
1140
(avg: 1178)

 

[B]

Very interesting, I'm getting basically the same velocity out of a 4.2" barrelled 686 with the same bullet. My app shows 1153fps with 15 grains. As I went higher my average actually started to decrease. I saw the same thing using AA9. I don't bother with magnum primers though, not needed with 2400.

 

[Auggie Doggie]

1119 to 1270fps in group #1 is a 151fps spread. Seems like quite a bit.

Auggie D.

 

[legi0n]

those velocities are quite low
here's mine in a 6" GP100 with lead bullets hardcast to 18+BHN

 

[B]

1119 to 1270fps in group #1 is a 151fps spread. Seems like quite a bit.

Auggie D.

I found that using mag primers with powders not requiring them often causes huge velocity spreads.

 

[legi0n]

I found that using mag primers with powders not requiring them causes huge velocity spreads.

not my experience. See the last two columns in my sheet. One is magnum primer. (I was running a comparison to see if A2400 needs magnum primers)

 

[B]

not my experience. See the last two columns in my sheet. One is magnum primer. (I was running a comparison to see if A2400 needs magnum primers)

I saw your post. My data says otherwise, I test every load/powder with both regular and magnum primers. Never had any use for them in the .357 except with H-110. I have only tested 6 powders or so though.

 

[DarkSkyx]

1119 to 1270fps in group #1 is a 151fps spread. Seems like quite a bit.

Auggie D.

The crimps were probably tighter on some than others, me thinks. I don't case trim, and all these shots were probably about the 8th reload on them, so if there was any minimal case stretch, it would cause a tighter crimp.

 

[DarkSkyx]

Very interesting, I'm getting basically the same velocity out of a 4.2" barrelled 686 with the same bullet. My app shows 1153fps with 15 grains. As I went higher my average actually started to decrease. I saw the same thing using AA9. I don't bother with magnum primers though, not needed with 2400.

Yah - magnum powders are generally slower burning so anything over a certain amount will end up burning OUTSIDE the barrel. Makes for a nice muzzle flash, but won't do much to increase the speed of the bullet.