Author: britrifles
Subject: Mk 7z vs my Match Loads
Posted: December 27 2023 at 5:34am
Interesting your Varget loads have 60 fps more velocity with one grain less powder than my loads. Must be the different bullet (PPU vs SMK).
Subject: Mk 7z vs my Match Loads
Posted: December 27 2023 at 5:34am
Interesting your Varget loads have 60 fps more velocity with one grain less powder than my loads. Must be the different bullet (PPU vs SMK).
Hodgdon on-line data for the 174 SMK is 38.0 minimum and 42.0 maximum. Pressure at 42.0 gr is 43,800 CUP significantly below the SAAMI max of 45,000 CUP (which is conservative for the Lee Enfield, particularly the No. 4).
Notice that with a 174 Hornady round nose, max charge is reduced to 39.0 gr at 47,100 psi piezo pressure.
Interpolating on the Hodgdon pressure data for Varget with 174 SMK, 40.0 grains would produce 41,300 CUP, quite mild for .303.
Note that although Hodgdon publishes this data on their website, it is actually developed by the powder manufacturer, ADI. Hodgdon sells ADI AR2208 under the name Varget and their data is identical to ADI online published values for AR2208. We can trust the ADI data.
With my DCRA 7.62 No. 4 Mk 2, best accuracy comes with midrange .308 Win Varget loads at 45,000 to 46,000 CUP. This load shoots sub-MOA prone with PH 5C sight out to 800 yds. 7.62 NATO loads can be as much as 50,000 CUP which presumably the No. 4 action is strong enough to withstand, although I prefer to keep loads to within 45,000 CUP.
The way the barrel is bedded in the forend (location of barrel bearing) likely affects what bullet velocities perform best. My 7.62 DCRA is bedded at the middle band and free floating out to the muzzle and back to the reinforce.
