Author: britrifles
Subject: Effect of Primer Selection on Muzzle Velocity
Posted: January 29 2025 at 4:51am
Shaun, this forend has a barrel bearing at the middle lightening slot in the forend, just behind the sling swivel band. The slot was filled with wood and a hardwood bearing block glued in. I’ve measured the barrel pressure on the bearing, but can’t remember what this was. The work was done by the DCRA Armorer in the 1960’s. I’ve shot some very good groups with this rifle, approaching 1 MOA at 300 yards. 600 yard groups are larger, 2 MOA at best.
Subject: Effect of Primer Selection on Muzzle Velocity
Posted: January 29 2025 at 4:51am
Shaun, this forend has a barrel bearing at the middle lightening slot in the forend, just behind the sling swivel band. The slot was filled with wood and a hardwood bearing block glued in. I’ve measured the barrel pressure on the bearing, but can’t remember what this was. The work was done by the DCRA Armorer in the 1960’s. I’ve shot some very good groups with this rifle, approaching 1 MOA at 300 yards. 600 yard groups are larger, 2 MOA at best.
I believe the scope and mount affects the muzzle “jump”. The mount is quite stiff. Maj Reynolds wrote about a trial carried out by the Small Arms Inspectorate at Enfield in 1945 on 24 No. 4 T rifles to ascertain the affect the telescope and mount had on the angle of jump:
Without Scope Fitted 4.5 to 12.5 Minutes
With Scope Fitted -2.0 to 4.75 Minutes
Clearly, the scope does have an affect. I don’t know how much jump would be necessary for the rifle to show positive compensation, but it would have to be a positive (muzzle moving upward) value. The test shows some rifles had a negative angle of jump (muzzle moving down as the bullet exits the barrel).
None of this should affect muzzle velocity though. I still don’t have a good explanation to offer for why I’m getting large extreme spreads. But I am hoping that leaving some carbon fouling in the grooves will settle it back down to where this rifle was shooting before. 2 MOA at 600 yds May be as good as it gets with this barrel.
