375 RUM and the 260 Accubond...

[Doublezranch]

Hey guys and gals,

I have heard now from a couple of you how devistating the 270 tsx is in this caliber, but I just love the BC of the 260 Accubond. Soo, has anyone developed a long range, "killer " load for this combination? In doing research, my heart leads me to IMR 4350 because of the velocities its showing (3026) however, I know 4831 in hodgon and IMR are very close seconds. Is there a powder that anyone has tried other than the powders listed? I am shooting a 26 inch factory barrel.

 

[mrultramag]

I use IMR 4350- 96 gr w/ rem 9.5M. Wonderful load. However; I would be curious about RL17 or maybe 19. I didn't get the velocity listed w/ H4831 or IMR7828. 4350 was as advertised for me.

 

[Doublezranch]

Interesting...I shoot 7828 out of my 7 RUM and 338 RUM with unyielding success. Accurate, consistant charges that shoot and ignite very well. I'm not suprised that 7828 isn't the answer in this caliber. I think it is just too darn slow of a powder. However, 19 and 17 might be something to try...

 

[Kennibear]

I shoot the 260AB in a 375 Ruger from a Savage 116 with a factory custom 26" barrel. 79.5grs of WW760 yields 3022fps with absolute max pressure (Pressure Trace II says 62kpsi). For this much powder I always use a Fed 215 LRM primer. My son gets top velocities out of 7828 in his 300 WinMag but RL 19 has proved very promising in his gun. As the 300 WinMag has a bore ratio closer to the 375 RUM I would try that powder. It has a high energy density and the burn rate is very close to 4831/7828.
Since my rifle is generating similar velocity to yours the load you are using is not optimum. Try a different powder and switch to the Fed 215LRM primer. They make it in a match version also I believe.

 

[mrultramag]

DoubleZRanch- yes 7828 works well in my 7 rum with 140's as well. I like RL25 in my 300 rum w/200's.

 

[Doublezranch]

DoubleZRanch- yes 7828 works well in my 7 rum with 140's as well. I like RL25 in my 300 rum w/200's.

I shoot half inch groups at 300 with 7828 in my 7 RUM and get the same or better performance with my 338 RUM with 7828. There is no way I am changing their loads. Way too accurate. I am trying to put together a consistant, long range thumper of a load for my 375 ultra.

My 300 RUM shoots H1000 and I'm planning on shooting rl-33 when I can get sometime to play.

 

[Kennibear]

DoubleZranch
Might want to look at Hodgdon's Superformance. Used it in development loads for the Hornaday 300gr SpBt in the 375 Ruger. The two loads were 80gr of IMR 4350 and 83.3gr Superformance. The 4350 showed about 56 - 57kpsi (Pressure Trace II) and the Superformance was about 4kpsi less. These loads were from Hornaday's Manual but they are safe even with their Copper clad steel jacketed DGX/DGS Dangerous Game bullets. Steel jackets have a much higher pressure coefficient so the AccuBond would be safe with a comparable ratio of 4350/Superformance. Superformance works at about 60kpsi and it isn't for every load but where it works it is the best. Superfomance has a burn rate about the same as 4831 and RL19.

Ball park load is 92grs but I would start lower and work up to reasonable pressure signs. The 80gr 4350 - 300gr Spbt load in the 375 Ruger was heavily compressed but the 83.3gr Superformance load was about 100% density. You can pack a ton of Superformance in a case - very dense powder. As always a Federal #215 LRMag primer.

Just my two cents....

 

[Doublezranch]

What type or shape is the superformance powder? Ball, rod, hybrid...?

 

[barnesuser28]

"In my research".......

 

[Kennibear]

Doublezranch

Ball, fine grained and almost no flattening. Meters very uniform in a Lyman #55 or a Lee Perfect Powder Measure. The Lee may be at the upper end of it's capacity to meter that much powder as the 375 RUM can use about 100grs+.

In 30-06 Hornaday and Hodgdon do not require a magnum primer but anything that has 70grs+ of powder to set fire to I use a Mag primer.

It is a "tailored" powder meaning the Chemical Engineers gave it specific characteristics as to grain size, nitroglycerin content, deterrent coatings etc. so it works in a narrow range of conditions unlike, say, 4895 which has a broad application and tolerance. 4895 will burn well anywhere from 20kpsi to 62kpsi but Superformance is supposedly designed around 58kpsi - 62kpsi according to what I've read. Also read that as it is a new technology ball powder it is far less sensitive to temperature fluctuation than traditional ball powders.

In today's world we reloaders enjoy the best selection of components ever. When I started in 1971 there were maybe 12 - 18 different rifle powders and may be that many shotgun/pistol offerings. 4831 was surplus only from Hodgdon's and Alliant had RL 7 and RL17. Last time I looked there were 138 different powders on the market.

Don't rule out the Scandinavian powders, Norma or VitaVourri. They are different enough to explore and back in 1974 I had a load in 30-06 that tossed a 200gr pill faster than anything else with Norma 205. The pressure signs were nonexistent.

Superformance is on my short list of powders to try if I need something in a burn rate around 4350/4831.

Just my experience...

 

[Doublezranch]

Alright Riley....

When I started this quest, I asked for Riley's knowledge. His recommendation was IMR 4350 and 260 accubonds. Kids.....

 

[Doublezranch]

Thanks Kennibear for the education. It sounds like you have a very good understanding of powder and I appreciate your willingness to explain. I will give superformance a try.

 

[mrultramag]

Real Guns - Handload Data - 375 Ultra Mag

This might provide a few ideas as well.

 

[Lefty7mmstw]

Alright Riley....

When I started this quest, I asked for Riley's knowledge. His recommendation was IMR 4350 and 260 accubonds. Kids.....

If you had a regular 375h@h like I do, I'd say 4320.. It's worked well for me with the 260 ab, though I'm only loading the 300tsx with 4320 at present.. With your extra capacity 4350 should work well.

I've worked with superformance a bit and it does well in my 25wssm, but it's flaky to bullet and primer. Change one parameter and a moa load goes to three. Of course this is win bbl. I'm working with so take that with a grain of salt.