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