Author: britrifles
Subject: M30 170grn FMJ-BT Update
Posted: September 02 2023 at 3:52am
Subject: M30 170grn FMJ-BT Update
Posted: September 02 2023 at 3:52am
 Goosic wrote:Sapper740: I have alot of original 1941', 42', and 43' Winchester MkVIIz ammunition and chronographed 48 rounds of the 1943 lot and the averaged MV was 2545 fps so I used that information in comparison with my new test rounds... |
All the Mk 7 and 7z ammunition I have chrono’ed thru several different No. 4 rifles (20 feet from muzzle) gave velocities in the range 2430 to 2450 fps. The specification velocity for the Mk 7 cartridge (both 7 and 7z) was 2440 fps. If you’re getting 2545, I suspect either an issue with the chrono, the powder has deteriorated giving higher pressures/velocities (which can happen), or the Winchester quality controls were poor on those lots.