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Hi guys,
Thanks for the advice above.
Before I tried different powders, I went down the range today with the Club Chrono to try my standard powder Viht N320.
I tried a number of different bullets with the maximum load and compared it to my usual target load. I did not go for accuracy I was checking velocity to see if it would drop subsonic over 100 metres, hinting a more powerful powder may be required.
The results were as follows:-
Load 1 - Standard Target Load
Calibre: .357 Magnum
Case: S&B .357 Magnum - fired 3 times
Primer: CCI Small Pistol
Bullet: GM Hardcast 158 grain TC
Powder: Viht N320
Charge: 4.8 grains - maximum .38spl load from Viht load data
Rifle: Uberti Winchester 1873 Sporting
Barrel: 24 1/4 inch
Velocity: 1,066fps
Energy: 399ftlb
Load 2 - Maximum Load - Lead
Calibre: .357 Magnum
Case: S&B .357 Magnum - fired 3 times
Primer: CCI Small Pistol
Bullet: GM Hardcast 158 grain TC
Powder: Viht N320
Charge: 6.6 grains - maximum .357mag load from Viht load data
Rifle: Uberti Winchester 1873 Sporting
Barrel: 24 1/4 inch
Velocity: 1,320fps
Energy: 611ftlb
Load 3 - Maximum Load - TMJ
Calibre: .357 Magnum
Case: S&B .357 Magnum - fired 3 times
Primer: CCI Small Pistol
Bullet: 158 grain Total Metal Jacket RNFP
Powder: Viht N320
Charge: 6.6 grains - maximum .357mag load from Viht load data
Rifle: Uberti Winchester 1873 Sporting
Barrel: 24 1/4 inch
Velocity: 1,210fps
Energy: 514ftlb
Load 4 - Maximum Load - Polymer
Calibre: .357 Magnum
Case: S&B .357 Magnum - fired 3 times
Primer: CCI Small Pistol
Bullet: 158 grain TC - polymer coated - green
Powder: Viht N320
Charge: 6.6 grains - maximum .357mag load from Viht load data
Rifle: Uberti Winchester 1873 Sporting
Barrel: 24 1/4 inch
Velocity: 1,310fps
Energy: 602ftlb
Based off this, I think I can see why it isn't doing well at 100 metres.... I haven't ran the numbers in a ballistic calculator but I believe it's dropping subsonic and destabilising.
As a result I've today acquired a tub of H110 and will try again with this project. Hogdon data puts the rifle velocity out of an 18 1/2 inch barrel between 1600 and 1750fps... Lyman has larger loads listed too.
Ta
Andy
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