Retumbo, H1000 Barrel Length???


Well-Known Member
Oct 23, 2009
Iv just started reloading for my 300RUM and it has a 25.25" barrel. Iv been loading up some Retumbo for it. My question is with a 25.25" barrel will I get the most velocity out it or should I use maybe a little faster burning powder. I know most ultra mags have at least 26" barrels on them so it got me thinking if it would be a better idea to try H1000 or something faster? I dont have a chrony so I dont know my velocity and Iv been loading 210gr bergers and 200 accubonds. Any advice would be appreciated.
Sounds like you may have a Sako or a Tikka. You need not worry however, 3/4 of an inch will not make a noticable difference. Just find the load that shoots the best and go with it. Good luck and God Bless

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Without a chronograph, you're simply guessing at velocity.

My experience with the .300 RUM and the heavier bullets is that Retumbo will give consistently higher velocity over the others.

I suggest you do comprehensive load development with a few different powder and bullet combinations to see what the rifle likes, not what you want it to shoot.
I also shoot short barrels: 15"-18" with cartridges like 6-284, 7mm Dakota, and 338 Lapua Improved.
I pretty much use the slower powders myself too, or I will use the next fastest burn rate from teh slowest one typically used in longer barrels:
Such as, H-4831sc for my 6-284, H-4350 and or Hybrid 100V for my 6.5-284's, H-1000 for my 7mm Mag Imp, Retumbo with my 7mm Dakota, and Retumbo with my 338L Imp.
All of these have barrel lengths that I have listed above.
Find what is most accurate for your rig and be happy and as mentioned a chrono will tell you alot.
I just did an experiment that might help you out! I shot the max h1000 load compared to the max retumbo load in the seirra book and the h1000 averaged 2710 and the retumbo averaged 2890. the retumbo wazs definately hotter load, the h1000 could have went a little hotter to match the primer markings on the retumbo!
Just a thought,

My bunting bud, worked up loads with both Retumbo and H-1000. He foud that while the Retumbo did give higher velocities, it also loosened up pockets on the bras faster than the h-1000 did. So you might give that some consideration due to the state of affairs we have in getting components these days.

If you r happy with getting three to five loads verses the same accuracy and getting 12 - 15 loads per case, then no biggie either way.

Just some food for thought.
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