Home Forums Reloading Big Game Rifles 308 win loads

I'm also posting this in the Gunwriters section. I verified two loads at 100 yards for my 308win Remington 5R yesterday at the range. First load was 43.2 grains of IMR 4064, 175 SMK, BR-2 primer in Remington cases. Seven shots 1/2 MOA, 2662 fps avg. ES 22, SD 6. Second load was 47.5 grains of CFE 223, 175 SMK, BR-2 primer in Remington cases. Five shots less than 1/2 MOA, 2774 fps avg. ES 17, SD 6. The next outing will be at 200 & 300 yards. Now for the question. I load some subsonic rounds using 10 grains of Trailboss and 165 HPBT SGK's at 50 yards. Shot (1) 1101 fps, (2) 1109 fps, (3) 1077 fps, (4) 1064 fps. First three shots straight in, fourth shot alittle side ways (not complete key hole). Could the Trailboss be fouling the barrel differently to the point of slowing down the subsonic loads. All of the loads where weighted on a GemPro 250. Thanks for some insight.

I doubt it's fouling that's causing your issues. At those velocities and with your twist rate and altitude, you are just on the ragged edge of bullet stability.

I load 11 grains of Trailboss with 170 grain partitions made for 30-30’s. Damn accurate at 50 yards. Kills pigs at 50 yards.

You need more data. I don't think fouling is the issue, but it could be a stabilization thing. Stretch the distance and see what happens. Could have been a fluke, or you could be struggling to stabilize the bullets. Doing some rough estimations using Berger Bullets' stability calculator, it looks like it could go either way.

I tried Trailboss in my .308 after reading an online piece. Results were so-so. Going to try 5744 cast-bullet data next. 20gr seems to be a good place to be according to the Lyman 50 and another article I just read. Should just about duplicate original .30WCF loads.