7x57 - Not Supposed to Do This - 07/22/20
I posted some of this on another thread, but yesterday got my digital caliper out in order to get some precise measurements (old eyes and dial caliper just doesn't cut it anymore). Here's the back-story.
A couple of years ago I bought a M1909 Argentine Mauser that had been bedded into a B&C Carbelite stock. I bought it because I wanted something I could use in the wet weather that we have during our rainy season. The rifle shot ok, but the barrel was a pretty heavy profile, so I sent it off to have a few things done to it: check for lug set-back (there was none), have the action hardened, and then turn down the barrel. The 'smith used an old Rigby profile on the barrel, including the step, and finished it at .540 inches at the muzzle (24 inches). It took almost a pound off the entire rifle, bringing it to 7lbs, 2oz on the scale. I put an old 3-9 VXII on it, mounted in old-fashioned Weaver tip-off rings and Weaver base. Now the entire outfit comes in right at 8lbs. Not bad for an old, heavy military action.
Since this rifle will spend most of its life chasing pigs, I loaded up some 175-gr Hornady Round Nose Interlocks that I got a while back from Rocky Mountain Reloading. I loaded six three-shot groups, starting at 41.0 grains of IMR4350 and worked up to 43.5 in half-grain increments. Brass was Prvi, primers were WLR, and the CBTO was 2.635 inches, .010 off the lands. I didn't chronograph any of the loads, but using the data in Nosler's manual, I adjusted for a 24 vs. the 22 inch barrel they used in developing their data. I came up with about 2400 fps for the 41.0 grain load, and about 2500 fps for 43.5.
Here's where things get interesting.The first 100 yard three-shot group measured 1.607 inches CTC. Each subsequent group tightened up just a bit until I got to groups 5 and 6. Group 5 tightened up considerably to .661 inches CTC, and group 6 went .387 inches CTC. .387 inches! I suppose I could tweak the powder charge and seating depth to maybe even improve on that, but I'm not consistent enough off the bench to make it happen. Considering the fact that I was going to be content if this rifle shot around 1.5 MOA, I think I'm going to stop right there. Just about everything I shoot is inside of 125 yards or so, generally much closer to inside 75, this load will do.
I never dreamed that this old cobbled-together Military Mauser would be capable of anything even close to this, especially with that particular bullet. I guess I'm not all that interested in a 7-08 anymore.
Sorry for the crappy smartphone pictures. I ought to learn to use my wife's camera.
175-grain Hornady Interlock Round Nose
Turned down barrel with step
Finished rough weather Mauser
Three shots into .387 inches. That load is a keeper.
A couple of years ago I bought a M1909 Argentine Mauser that had been bedded into a B&C Carbelite stock. I bought it because I wanted something I could use in the wet weather that we have during our rainy season. The rifle shot ok, but the barrel was a pretty heavy profile, so I sent it off to have a few things done to it: check for lug set-back (there was none), have the action hardened, and then turn down the barrel. The 'smith used an old Rigby profile on the barrel, including the step, and finished it at .540 inches at the muzzle (24 inches). It took almost a pound off the entire rifle, bringing it to 7lbs, 2oz on the scale. I put an old 3-9 VXII on it, mounted in old-fashioned Weaver tip-off rings and Weaver base. Now the entire outfit comes in right at 8lbs. Not bad for an old, heavy military action.
Since this rifle will spend most of its life chasing pigs, I loaded up some 175-gr Hornady Round Nose Interlocks that I got a while back from Rocky Mountain Reloading. I loaded six three-shot groups, starting at 41.0 grains of IMR4350 and worked up to 43.5 in half-grain increments. Brass was Prvi, primers were WLR, and the CBTO was 2.635 inches, .010 off the lands. I didn't chronograph any of the loads, but using the data in Nosler's manual, I adjusted for a 24 vs. the 22 inch barrel they used in developing their data. I came up with about 2400 fps for the 41.0 grain load, and about 2500 fps for 43.5.
Here's where things get interesting.The first 100 yard three-shot group measured 1.607 inches CTC. Each subsequent group tightened up just a bit until I got to groups 5 and 6. Group 5 tightened up considerably to .661 inches CTC, and group 6 went .387 inches CTC. .387 inches! I suppose I could tweak the powder charge and seating depth to maybe even improve on that, but I'm not consistent enough off the bench to make it happen. Considering the fact that I was going to be content if this rifle shot around 1.5 MOA, I think I'm going to stop right there. Just about everything I shoot is inside of 125 yards or so, generally much closer to inside 75, this load will do.
I never dreamed that this old cobbled-together Military Mauser would be capable of anything even close to this, especially with that particular bullet. I guess I'm not all that interested in a 7-08 anymore.
Sorry for the crappy smartphone pictures. I ought to learn to use my wife's camera.
175-grain Hornady Interlock Round Nose
Turned down barrel with step
Finished rough weather Mauser
Three shots into .387 inches. That load is a keeper.