375h&h guidance - bullets, dies, and brass

[benchracer]

Quick update.

Unfortunately, it appears RL-15 has become unobtainium just after I got my suppressor out of jail and my barrel cut to continue trials.

I have copious amounts of varget and some H4350 that I will run a few trials in initially.

That being said - it appears the heir apparent of RL-15 is RL-15.5.
Does anyone have experience with this in 375h&h in a 270 TSX?

I am just beginning to work with TS 15.5, but not in 375 H&H. I am finding that it is not as slow burning as I had expected. In .308 Win, powder charges are staying within one full grain of VARGET and picking up about 40 to 50 fps in muzzle velocity. TS 15.5 will sit between VARGET and H4350 in burn rate, but it is less bulky than H4350, so it will take up less case volume.

 

[Javaman]

h4350 is probably the optimum powder for 300 gn bullets in the 375.
the reason is that the slowest burning powder that will give the velocity also has the least pressure.
so you get best velocities at lower pressure, AND h4350 is fairly temp stable.
this powder burning rate has a tipping point with 270 gn bullets in 375, working well with them, but lighter than that a faster powder is preferable.
in the old days, the next slowest powders were re15, varget, and 4064.
these are ideal for 235 gn bullets in 375, but too fast for 250, 260, and definitely 270 gn bullets.
now there are powders in between that will suit 237 to 260 gns.
yes re 15, varget, etc, will give the speed, but at what pressure compared to slower powders?

Long time lurker, first time poster.

I found the above info helpful to me last year in Limpopo. YMMV.

Cheers,

Javaman