There's a lot about 303 loadings on the 'net if you search. Not the usual Reloader's Nest but the forums of those that particularly use and colt the Lee Enfield.
I think that the Ellwood Epps site had some loads too?
But from those that have been there before here is what I tried myself when I had a 303 SMLE and a 303 No4. Hope it helps:
Sierra Matchking 174 BTHP - 43.0 H-4350 - "Shoots very high at 25 yards indicating low velocity. However it is very accurate."
Sierra Matchking 174 BTHP - 41.5 H-4895 - "Bolt stiff to open and HARD BACK on locking lugs. Apparent high pressure. THIS LOAD IS OVER HODGDON MAXIMUM LOAD."
Sierra Matchking 174 BTHP - 38.0 H-4895 - "Matches point of impact at 25 yards and 200 yards (in actual test) with British military MK 7 ball ammunition) No pressure problems with CCI primers. Tested July 1997. There is no point in using loads over 38.0 grains of H-4895...I can see why Hodgdon gives 40.0 as maximum."
The "best" loadings favoured here in UK to duplicate Mk 7 British military ball were 42.0 grains of Vihtavouri N140.
Vihtavouri N140 was certainly the powder of first choice and excellent results were also had with 41.5 grains of Vihatvouri N140.
Less used but also favoured was 42.0 grains of Vihtavouri N150.
Posts: 6831 | Location: United Kingdom | Registered: 18 November 2007
A number of different loads were use to zero and set up the scope. All were full length resized. I had some loads with me that had been neck sized from been shot in a No.4 Mk II and they would not come close to chambering.
Mine works really well with a 180 Speer RN and either RL15 or RL17. The rifle is a dream to shoot and with a 1.5X5 Leupold weight is 7 3/4 lbs making it ideal to carry.
Posts: 98 | Location: Fraser Valley B.C. | Registered: 07 December 2005
Changed the scope to a Weaver 4x and sighted in with South African Ball ammo.
I then fired 3 shots with 125gr Sierra Pro Hunter 43 grains of IMR 4895 The third shot was fired just after I fired the military surplus ammo and hit below the paper.
This target was fired with the same bullet with 42 grains of IMR 3031