I find it interesting that you would want to use Trail Boss in a 375 H&H.
I use it primarily in the 45 Long Colt with lead bullets and although it works great and I like it, it is a dirty powder. It doesn’t produce enough pressure to seal the mouth of your case to prevent blowback.
Your 375 is rated at 62366 psi MaxP. Trail Boss at a 100% case fill of 26-28 grains with a 220 grain bullet produces about half of that pressure. The recoil well be very mild but be prepared to clear your chamber and cases. It well have a little less punch than a 303 British.
It’s my understanding that it’s not a good idea to compress Trail Boss, spiking pressures is a problem. I haven’t tested the theory so I wouldn’t know for sure.
Posts: 2650 | Location: Lakewood, CO | Registered: 15 February 2003
I have used Trail Boss mostly with Speer 235 gr SP in .375 H&H but have also tried it with the 220 gr Hornady. Both loads have been accurate (the Speer somewhat more so) and a pleasure in terms of lack of recoil. I have used this just as a practice load and have been very happy with it.
I had a chat with a rep from the ADI company who make trail boss. He said the fomual for working out a start load (with trail boss) is work out the volume of the case once you have seated the pill then start with 70% of that volume and work up from there.
Posts: 110 | Location: sydney australia | Registered: 22 May 2005