model 10 barrel advice

[Idaho]

I finally got to shoot the rebuilt rifle today. It was done entirely for break in. fired one shot and cleaned the barrel 4 times, then two shots and cleaned the barrel 5 times, then 4 shots and cleaned the barrel 5 more times.

I was using cheap factory FMJ 55 gr loads and did not expect much accuracy. At the end of the day it was shooting groups of about 1 1/2 inches. Back at my bench and I measured the distance to the lands with three different bullet types and found that this barrel does not have nearly as deep a throat as the factory one did. With the 1/8 twist in this tube I'm hoping that I can get some decent groups with 70 and 75 gr bullets. Loaded up a few for the range tomorrow. We will see.

[Idaho]

Update. I measured the distance to the lands of the new barrel for three different bullets. 70gr Berger VLDs, 75gr A-Max and 55gr V-Max. The throat on this barrel is a LOT shorter than the factory barrel was. I could actually load these touching the lands if I wanted to.

I chose to stay a few thousands off for the first go around. When I got to the range a friend was already there with a chronograph set up so we put my handloads through it. The 75gr A-max over 23 gr of H335 gave a four shot 1/2 inch group at 100 yards. The fifth round in that bunch clocked at 2801 fps which was 68 fps slower than the rest. It was 1/2 inch away from the group and opened the 5 shots to 1 inch.

I got similar results with a Varget load. The spread in velocity was evident in the group. It was still 1 inch but now I'm looking to pay closer attention to my powder charges. I'm going to invest in a powder trickler and set my beam scale up so that it is at eye level and easier to see. I think if I can get my velocity spread down to less than 10fps that my groups will get smaller.

Now I'm going to pay attention to seating depth to the lands, accurate powder charges and then play with neck crimp. There are ragged holes in my future.

I think I'm going to like this McGowan barrel.