I am soon going to be getting a Remington 700 Sendero SF II chambered in .300 RUM. I am most likely going to be shooting 180-210 grain bullets, which powder would yield the highest velocities, Retumbo or RL-25? If their is another powder that may yield higher velocities let me know. Thanks.

Braxton

Not sure which one would yield the highest speeds but I can say that every person that I know who runs a 300 Ultra they're all using 200 Accu's and R25.

Dober

And everyone I know that shoots a .300 RUM, runs 200-210s with Retumbo... and gets 3100-3250.

Don't be afraid to try both powders you mention. In the 200 gr's, Nolser AB's and Nolser Partitions are hard to beat. In the 180 gr's, try Swift Scirocco II's. Don't know about 3250, in 200 gr I get 3150.

I had both on hand so I tried both in my RUM with 200 gr accubonds. Retumbo gave higher velocity and they were both accurate enough.

Also a RL-25 user: 200 gr accubond/3200 fps/27" barrel.

RL-25 also works well with:

257 Roy/115 Berger VLD
7 STW/168 Berger VLD
7 Rem Mag/ 180 Berger VLD.

That's a good example of each gun being diffrent. Out of my 26" REM 700 BDL, with RL-25 I had pressure signs show up at about 3050fps. With retumbo I never seen any pressure signs, I stopped at 95.5 gr. as the accuracy was great for 3175fps. This is all with a 200gr. accubond.
I've got some loads made up to test in my .257 WBY. RL-25 and retumbo under a 115gr. berger VLD.

Put me with the RETUMBO crowd:

200yd group:




300yd Group:



The 3 of 4 shots requires explanation. The first 2 were in 1 hole, so of course I got all excited on the third shot I flinched so bad the 3rd shot was completely off the paper! I cursed my lack of shooting skill gathered myself back up and put the 4th shot back near the other 2. - Even a great load can't help if you jerk the trigger!

I could run my load warmer but it shoots too well to mess with.

Lastly 547yd 1 shot group results:




RL-25 is probably good too but IMHO Retumbo was MADE to shoot 200gr bullets in 300 ULTRA's. I've had great results with the same combo different powder charges in 2 other 300 ULTRA's......................................DJ

i use 95.5 gr retumbo fed gm 215 primers 200 gr accubond for 3200 fps.this groups under 1/2 moa out of my 700p

Good example. My Sako has a long throat (and maybe a large bore) and so most other rifles will acheive higher velocities with the same powder charge. 1/2gr more powder and you get 150fps more velocity. This is why you should always back off powder charges and work your way up while watching velocities.........................DJ

I also get 3180fps out of my Model 70 in 300 RUM using 94gn of Retumbo but the sleeper in the bunch is H 1000 which I used in other .300 Rums in Australia when they were first released with red hot results. Tried it here and it still works fine.

My Model 70 likes all 3 powders.

JW

Retumbo was more accurate for me, but R25 was just as fast

BTW- who's runnin 180NAB's over Retumbo?

Retumbo for me in 300 RUM and the 30-378.

more accurate and more velocity for me than RL22 or 25.

I shoot 96.0 grains of Retumbo and 180 Accubonds out of my Rem 700 with a 26 in. Hart barrel. I get 3325 fps and dime sized groups. 163bc

I have had better luck with retumbo in respect to velocity and accuracy.

I have had better luck with retumbo in respect to velocity and accuracy.

I've owned a 300RUM from their inception and now use RL25 with 200gr. NP's. Seeking both the high-ends of accuracy and velocity, I didn't need to look any further than RL25.

I get 3,189 fps with RL25. Seems to fit right in there with some results of a few others.

Give several powders a look see if you have them on hand........as was said, all rifles are a bit different.

Good luck.........

200 gr AB
92 gr of RL25
3147 Avg velocity
300 yard group .675"
SAKO 75 SS
Elk hate this load.