I have been looking for load data on the .300 ultra mag using retumbo powder and 200 gr. accubonds. I noticed that djpaintles said he loaded 95gr. retumbo with these same bullets, but this seems to be above every maximum load I can find with 200 gr. bullets and retumbo. The highest maximum load I have found is in the sierra catalog with 92.7 gr. retumbo using 200 barnes xfb bullets. Can anyone help me find load data for this, or DJ if you read this can you tell me how you arrived at that load? Thanks for your help.

http://stevespages.com/308.html has it listed at 96gr for a high. Stroll down to 300 Remington UM and click on that and find the 200gr bullet, and there is the selections of other powders also. Maybe some else has a book with it listed. Sierra has it 78.6gr to a high 92gr at 3000fps- Hornady has a 190 and a 220 gr bullet and 87gr to 96gr Max is what there tech's are looking at for the 200gr bullet. You know that Remington uses Imr 7828 in that Ultra mag and that is a very accurate powder. Imr lists a 200gr Nos-Partition 85.8gr 2990fps with Imr7828. Along with Nosler's Ballistics, they also list Imr7828-max load at- 87.5gr at 3102fps==85.5gr at 3023fps== 83.3gr at 2951fps.

First of all although this load is perfectly safe in my rifle I'm glad your double checking and working slowly because it may or may not be safe in yours.

I couldn't find specific load data for the 200gr Accubond and Retumbo So I did a little interpolating.
The Hornady Manual lists 98.9 grs of Retumbo as a max for their 190 gr bullet and a Velocity of 3200fps
The Hodgen Annual manual list 96.0 for the Hornady bullet with a overall length of 3.555, and lists 100.5 as a maximum for 180gr bullets
I started several grains below and worked up in 1/2gr increments. Also I'm using a longer than normal OAL which reduces pressure somewhat. My rifles magazine and throating allows an overall length of 3.715, .115 over normal max OAL.
This load and OAL is definitely too hot for some of rifles. I shot 1 rd in a friends custom winchester and the got velocities of about 3250 and a blown primer. Probably due to being seated into his lands. I get velocities around 3050fps and multiple reloads out of the same cases. I definitely worked up the load from a ways down and feel perfectly safe shooting it in my rifle. The velocity is right about where it should be. I've loaded for 4 different Sako in 30 Caliber and they all seemed to accept maximum powder charges while delivering normal or slightly below normal velocities, I think that maybe their 30 cal barrels might be on the large side of tolerances.

All the above being said I probably shouldn't have listed the actual powder charge. I know it's perfectly safe in my rifle with the longer OAL and proper velocities but It might not be safe for some peoples rifles. Again use caution and work up slowly. If you are hitting over 3100fps I would think about backing off........DJ

I did a little interpolating myself and ended up with a load of 92 gr RL25 with 200 gr accubond lit by Fed 215M primer OAL 3.670 . Chrono's at about 3150. My gun is a mod 700 with a longgggg throat. Case life is very good. Every rifle is different so work up safely from below. This load will put 3 shots almost touching at 100 yds if I keep my shooting and holding of my rifle consistent. Find your max for your gun. It could be a much lighter load than mine!

Thanks for your help guys. One more thing I would mention....I saw a study(maybe on this website) where they tested the pressure effects of different primers on the exact same load. I'm not sure what round they were using, but if I recall correctly they affected the pressure by a few thousand psi(I want to say 6000) but I could be wrong. Fed 215 and WIN large rifle were the hottest, Rem 9.5M the coolest, everything else in between. I never thought it would make that much of a difference. You guys probably already knew that, I just thought it was interesting....

I also use 95 grains of Retumbo. You can get this from interpolating from Hogdon's own data (100.5 for a 180 + 89 for a 220 divided by 2 = 94.75). http://www.hodgdon.com/data/rifle/300rem.php

The problem is most published 200 data seems to be for the Barnes X. It's probably correct for that bullet. That bastard has more friction than any other bullet I've ever used. If you put it on top of a max load for any other 200 grain bullet you'll pop a primer.

Ask me how I know....

I had a 300 ultra in a mod 70 classic.

I WORKED up to 96 grains of retumbo with a speer 200 grain bullet at 3200 fps.

The same load sent the 200 sierra gameking at just under 3200 fps. But I settled on 95 grains for this bullet.

I used factory 180 grain ammo as an overall length.

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I could not get as high of velocities when I tried imr7828

But I did get 3050 with a 220 grain matchking and 2850 with a 240 grain matchking and retumbo. lower grain charges of course.

I got my highest load data with steves pages and just work up my loads half grain at a time.