Mauser M03 - Accuracy - 243 Winchester

Before heading out hunting a few weeks ago and again yesterday I quickly loaded up some 243 Winchester rounds, to test for pressure with the new Lapua cases I'm using. I'm not doing serious load development yet, just some quick proofing. Any time spent at a noisy rifle range is time that could have been spent better out hunting.

The first time I tried the new 243 barrel was with Speer Grand Slam 100gn projectiles. The pic below shows that targets the size of pigs out to 200m are in trouble, by I want better than that. I loaded these three rounds with my new Wilson in-line dies and a K&M arbor press, so could feel the tension of the bullets being seated. The very end of each neck was turned in slightly from fire-forming, which made seating the next bullet difficult. I think this happened because I put a small chamfer on the outside of the neck rim with an RCBS neck chamfering tool. That slight bevel might be a problem under high pressure in the chamber, causing the end of the neck to be pinched in. I'd put two chamfer angles on the inside of the necks as well, to make seating easy, but the pinching inwards right at the opening was still a problem. Given the trouble I had seating the bullets, I wasn't expecting them to shoot well.

A poor group from badly loaded test rounds. 6mm Speer Grand Slam 100gn

Some new 95gn Berger VLD Hunting bullets had arrived in the mail, so I tried these with some fired cases that had the neck pinching rectified, with a K&M neck expanding tool. This is normally used to prepare cases for neck turning, but is also good for straightening out any neck pinching. These bullets seated smoothly and consistently. I set them to 20 thousandths of an inch from the lands on top of 42 grains of 2209.

Resting over the front of my Landcruiser again, in a bit of crosswind on a farm, the first shot with the Bergers, with a clean and cold barrel, landed right where I wanted it to. The point of impact was consistent with the Speer Grand Slams, so that's a bonus. I fired the second and had to look really closely through my Kahles 24 power scope. Same hole! I should have stopped there as I don't ever expect to shoot a feral beastie three times. The third shot landed slightly lower - could've been me shaking a bit - my Landcruiser is not a concrete bench. This is a great result for loads that were thrown together before heading out. 13.5mm centre to centre. I will be tuning this load by adjusting the seating depth and the powder charge, so it could get better. I might actually waste a morning at a range to see how good this barrel can be.

The bolt is from my new Mauser M03 Deluxe, which has the 243 Win barrel fitted at the moment. Once I have loads for this one sorted, I'll start on the 6.5x55 Match barrel. Should be good. :-)

A better group with 6mm Berger VLD Hunting 95gn.