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

 

[Datchew]

Update:

Good initial results switching to varget powder.

I'm getting 0.750" groups of 3 with 71.5 grains at a COAL of 3.560 off a bench.
I'm shooting with a 1-6x scope. I think I could tighten up with more scope magnification but this is well within minute of cape buffalo so no need to burn powder further or mess around with seating depth.

This chrono'd at an average of 2618 FPS which is roughly 4110 ft-lbs energy at the muzzle.
That's a 22" blaser R8 standard barrel with an AB Raptor 10 suppressor on the end.
It makes the 375 "feel" like a 300WM.

I'm going to shoot my drops out to 300, sight in a 2nd scope for backup, and call it a day.

I very much appreciate all the help and guidance as this is the biggest caliber load I've developed thus far.

 

[Javaman]

don’t fix it if it ain’t broke! Sounds like it’s shooting, good job!

 

[Rule 303]

Why would you need more magnification to shoot better? On 6 power the target is optically a bit less than 17 mts from you.

 

[Datchew]

With a 6x shooting at a 8.5x11" paper with 3 targets on it at 100 yards, the reticle is literally larger (thicker) than the target axis. It completely blocks it out.

I have to interpolate bullseye position by holding away in order to see it and then moving to hold it over my assumption for each shot.

With a higher magnification, I don't have this issue and can be more precise at distance. Especially when I run dope out to 300yds.

I can hunt to 250-ish with a 6x but paper punching small paper gets fiddly.