Reloading .303 British : Mk 7z vs my Match Loads

Isn’t that curious. My experience is just the opposite.

Loads that approach max for .303 and about equivalent to Mk7 velocities for an 174 gr bullet are the most accurate in my No. 4 rifles.  While I find that mild loads give good short range accuracy, they show inferior results past 300 yards.  At 600 yards, 174 grain bullets at low to modest velocities give inconsistent results.  Occasionally, they do very good at 600 yards, in the 1.5 to 2 MOA range for 10 shots.

The exception appears to be my DCRA 7.62/.308 Win. Best mid to long range accuracy with 168 TMK is at fairly high velocities, 180 fps higher than .303 Mk 7 specification, 2620 fps.  The 175 TMK also shoots exceptionally good at long range when pushed at muzzle velocities of around 2550 fps, 110 fps above .303 Mk 7 velocities. I’m talking 1/2 MOA, shoots like a laser, only limited by shooter skill.  These .308 loads produce about 45,000 CUP, perhaps a bit less as I’m seating bullets out longer than what is in the load tables.  After firing several hundred rounds with these loads in the DCRA, there is no signs of excessive pressures.  No primer flattening, very easy bolt handle lift, cases are on their 6th reload.

I stick with 40.0 gr Varget with 174 SMK in my .303 because it is a mild load and produces good 200 yd accuracy, certainly sufficient to win the 200 yd vintage service rifle matches, but I’ll likely have to tweak this for the No. 4T used in 300 and 600 yd vintage sniper matches.  I do plan to run a ladder test on the T to find the optimum charge weight in the range of 39.0 to 42.0 grains. I want to get 600 yard groups to be within the 10 ring (2MOA).