Acording to last year's Annual Mannual by Hodgdon, Trail Boss can be used in virtually all modern 'nitro' guns. In the .45/70 tested, a 405gr. bullet developed a high of 25,600 CUP (PSI)(identical #'s in the .45/70 and many straight cases)at a mere 1,007fps.

The highest pressure recorded by Hodgdon in testing was in one of the .300 mags, with a 180gr. jacketed bullet and a full case of powder - not-compressed (do not compress it) at 36,000PSI and a velocity of 1,700fps.

Some of the small bore shooters (.17's or .20's) are recording speeds over 2,000fps - so perhaps they are compressing it. My .17AH would produce only 1,745fps with a max load of 3.7gr.

I would not hesitate to use it in anything I own- having ued it in the .45/60, .375/06IMP and the .17AH, with jacketed bullets only in the .17 cal., which produced the highest velocity and pressure, which was evident by the almost perfect case forming that resulted. I suspect pressures well over 35,000 to 40,000CUP as it takes that much pressure to properly form the brass without cracking the shoulders. TYhey cannot be formed with light pressure.

Full case to the bottom of a seated bullet is the max load. 70% of that is a starting load. Simple rules for simple loading.