After shooting my 39 rounds of 357 Super Mag, I took out the 44 Mag to chrono my reloads and see if there would be a significant increase in velocity when the cylinder gap was shortened from .006" to .002"  It makes sense that it would because less gas is escaping in a .002" gap than in a .006" gap therefore more gas to push the bullet.  The Chrono results indicate an increase in velocity with a shorter gap.  HOWEVER, I did shoot all the .006" strings first and then changed the Gap to .002" so the gun was warm and this could also have been a factor in increasing velocity.  I guess the next time out I will start with the .002" and a cooler gun with this gap, then change to the .006" gap and see if the results are repeatable.   Any way here is the Data.

Observations on Alliant Power Pro MP-300---- It is a flame thrower and it is the only powder so far that causes my chrono to have some reading errors, I imagine it is because the of the flame flash that follows the bullet messes with the chrono.  

 

Set: 54
Created: 06/15/15 01:55 PM
Description: Dan Wesson 44 mag 10" barrel .002" gap
Notes 1: MP-300 24 gr Fed. LP
Notes 2: Hornady XTP 240
Distance to Chrono(FT): 10.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 240.00
Temp: 84 °F
BP: 29.96 inHg
Shots:
#    FPS / FT-LBS
5    1309 / 913
4    1325 / 936
3    1283 / 877
2    1275 / 866
1    1299 / 899
Average: 1298.2 FPS
SD: 20.0 FPS
Min: 1275 FPS
Max: 1325 FPS
Spread: 50 FPS

True MV: 1299 FPS

Set: 48
Created: 06/15/15 01:32 PM
Description: Dan Wesson 44 mag 10" barrel .006" Gap
Notes 1: 300-MP 24 gr Fed LP COL 1.6115"
Notes 2: Hornady 240 gr XTP
Distance to Chrono(FT): 10.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 240.00
Temp: 84 °F
BP: 29.96 inHg
Shots:
#    FPS / FT-LBS
5    1248 / 830
4    1238 / 817
3    1232 / 809
2    1295 / 894
1    1217 / 789
Average: 1246.0 FPS
SD: 29.6 FPS
Min: 1217 FPS
Max: 1295 FPS
Spread: 78 FPS

True MV: 1247 FPS

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Set: 53
Created: 06/15/15 01:47 PM
Description: Dan Wesson 44 mag 10" barrel .002" gap
Notes 1: H110 23 gr. CCI LPM
Notes 2: Hornady XTP 240
Distance to Chrono(FT): 10.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 240.00
Temp: 84 °F
BP: 29.96 inHg
Shots:
#    FPS / FT-LBS
6    1359 / 984
5    1290 / 887
4    1273 / 864
3    1297 / 897
2    1286 / 881
1    1262 / 849
Average: 1294.5 FPS
SD: 34.0 FPS
Min: 1262 FPS
Max: 1359 FPS
Spread: 97 FPS

True MV: 1296 FPS

Set: 46
Created: 06/15/15 01:27 PM
Description: Dan Wesson 44 mag 10" barrel .006" Gap
Notes 1: 23 gr H110 CCI LPM COL 1.6065"
Notes 2: Hornady 240 gr XTP
Distance to Chrono(FT): 10.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 240.00
Temp: 84 °F
BP: 29.96 inHg
Shots:
#    FPS / FT-LBS
6    1231 / 808
5    1223 / 797
4    1234 / 812
3    1268 / 857
2    1249 / 831
1    1250 / 833
Average: 1242.5 FPS
SD: 16.3 FPS
Min: 1223 FPS
Max: 1268 FPS
Spread: 45 FPS

True MV: 1243 FPS

--------------------------------------------
Set: 52
Created: 06/15/15 01:44 PM
Description: Dan Wesson 44 mag 10" barrel .002" gap
Notes 1: Unique 10 gr. Fed LP
Notes 2: Rainer Plated 240 gr. COL 1.582"
Distance to Chrono(FT): 10.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 240.00
Temp: 84 °F
BP: 29.96 inHg
Shots:
#    FPS / FT-LBS
6    1022 / 557
5    985 / 517
4    1010 / 544
3    989 / 521
2    1038 / 574
1    983 / 515
Average: 1004.5 FPS
SD: 22.5 FPS
Min: 983 FPS
Max: 1038 FPS
Spread: 55 FPS
Shot/sec: 0.4
True MV: 1005 FPS
Group Size (in): 0.00

--------------------------------------------
Set: 51
Created: 06/15/15 01:39 PM
Description: Dan Wesson 44 mag 10" barrel .002" Gap
Notes 1: Unique 10 gr. Fed LP
Notes 2: Rainer Plated 240 gr. COL 1.582"
Distance to Chrono(FT): 10.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 240.00
Temp: 84 °F
BP: 29.96 inHg
Shots:
#    FPS / FT-LBS
6    1048 / 585
5    972 / 504
4    1012 / 546
3    1047 / 584
2    967 / 498
1    996 / 529
Average: 1007.0 FPS
SD: 35.4 FPS
Min: 967 FPS
Max: 1048 FPS
Spread: 81 FPS
Shot/sec: 0.4
True MV: 1008 FPS
Group Size (in): 0.00

--------------------------------------------
Set: 50
Created: 06/15/15 01:37 PM
Description: Dan Wesson 44 mag 10" barrel .006" Gap
Notes 1: Unique 10 gr. Fed LP
Notes 2: Rainer Plated 240 gr. COL 1.582"
Distance to Chrono(FT): 10.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 240.00
Temp: 84 °F
BP: 29.96 inHg
Shots:
#    FPS / FT-LBS
6    1000 / 533
5    1003 / 536
4    1001 / 534
3    968 / 499
2    965 / 496
1    977 / 509
Average: 985.7 FPS
SD: 17.6 FPS
Min: 965 FPS
Max: 1003 FPS
Spread: 38 FPS
Shot/sec: 0.4
True MV: 986 FPS
Group Size (in): 0.00

--------------------------------------------

I only had 5 rounds of 25 grain so they were all shot with a .006" Gap

Set: 49
Created: 06/15/15 01:34 PM
Description: Dan Wesson 44 mag 10" barrel .006" Gap
Notes 1: 300-MP 25 gr Fed LP COL 1.6115"
Notes 2: Hornady 240 gr XTP
Distance to Chrono(FT): 10.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 240.00
Temp: 84 °F
BP: 29.96 inHg
Shots:
#    FPS / FT-LBS
5    1342 / 960
4    1304 / 906
3    1306 / 909
2    1320 / 929
1    1314 / 920
Average: 1317.2 FPS
SD: 15.3 FPS
Min: 1304 FPS
Max: 1342 FPS
Spread: 38 FPS

True MV: 1318 FPS

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