Starting loads for 300 ultra and retumbo

[arthurj]

Hey guys, I've searched and searched and I can't seem to find any solid data for a 300RUM with retumbo. Where would you guys recommend starting for a 200 accubond, a 220 MK, and a 210 berger?
Thanks

 

[Michael Eichele]

Is this a factory chamber or a tight custom chamber??

If its a tight bench chamber I wouldnt use any more than 85 grains with the 200 grainer and would start closer to 77-78.

If its a factory chamber start with 87 and work up to 95 SLOWLY. Even 95 might be too hot depending on your location and lot# and so on. This is of course for the 200 grain bullets.

 

[arthurj]

It is a rifle kirby just built for me, it has a .344 neck, so not too tight but tighter than factory. He emailed me some starting loads but I lost them.

 

[Michael Eichele]

I have a .333 ND and a super tight chamber and 90.0 is MAXIMUM for the 180 accubond and 86.0 for the 200 accubond is max. Both RL-25 and RETUMBO give me the same velocities, but retumbo seems beat up my brass much more. If retumbo isnt quite the ticket try RL-25. Me and several buddies have had AWESOME results with it. The 1 load that my rifle excells with using retumbo is 95 grains with the 155 AMAX @ 3600 FPS. It will group .75" at 300 yards. I find the 178 AMAX does much better as it seems to fly MUCH flatter due to the high BC despite the fact I can only get 3300 FPS with it. I get 33" of drop at 600 yards with the 178 and 35" with the 155.

Good luck!

 

[arthurj]

Thanks a lot meichele, I think I'll have to give the amax a try.

 

[the444shooter]

Make sure you check your variations with RL25-it will give you the best velocity, but it is also plagued with variations by Lot# and temperature sensitivity. It may work just fine, but you will need to play with it a lot and under many different circumstances to determine whether or not it will be consistent. Retumbo is probably the way to go for consistency. As for myself, I will be using Retumbo with either the 180 Accubond or 180 TSX-the Remington Factory Scirocco ammo is too inconsistent, with deviations as much as 100fps.

 

[mrultramag]

with the 200 accubond, I ended up with a load of 95 gr retumbo, fed 215m primer, rem case, oal max to fit magazine on Model 700 rem. 300 ultra. It really liked this load and at 94 gr as well. Getting pretty close to max I think. No apparent pressure signs however. Need to shoot it more and see how soon the primer pockets loosen up. 92 gr of RL 25 is a tackdriver with the 200 accubond as well. I don't know if it is me or my imagination but it seems loads with RL25 have less recoil than with retumbo even with each loaded pretty close to max. Doesn't really matter anyway; its not that bad. Work up from below if you try these. Be careful with RL 25. you may have to adjust your charge for your lot of powder. I would say that 3150-3200 fps with a factory 26 in bbl rem 700 would be right at max with the 200 accubond and either retumbo or RL 25. I would give retumbo a ohsoslight edge in velocity. Each gun is different though.

 

[mrultramag]

There are a ton of loads out there for the 300 ultra. It seems the most popular for hunting rifles depend on Retumbo or RL 25 for powder. Educate yourself on max loads for the 300 and drop 10% for starting loads. Get a good Chrono and start working up your load watching for pressure signs as you increase your charges. Beware if you are getting 100 to 200 fps more than anyone else similiarly equipped. You may be too hot. On the Rem brass, loads too warm will usually loosen primer pockets real fast. The Rem ejector will make its mark known on the case head too; but this is not all that reliable. I've had factory loads do this before.

 

[Wild_Bill]

Hi this is the Published data by ADI that devolped Retumbo especialy for the 300 RUM i shoot with one of the balastitions that works at ADI the data is as follows.

ADI AR2225 (Retumbo)
300 Remington Ultra Mag

Start, Vel, Pres, Max, Vel, Pres
190gr
90.0gr 3069fps, 56500psi, 96.0gr, 3204fps, 62500psi

200gr
81.0gr 2852fps, 56200psi, 86.0gr, 2988fps, 62800psi

220gr
84.0gr 2800fps, 56600psi, 89.0gr, 2905fps, 61900fps.

all data in a 24" test barrel

Hope it helps

Cheers Bill
Australia

 

[arthurj]

Thanks for that info guys.

 

[Derek M.]

Did you look at Hodgdon's website? They have some info there.

 

[arthurj]

Yeah I looked at it but they didn't have the specific bullets I wanted to shoot. I didn't know enough about the different bearing surfaces of these bullets to figure what the load should be. I finally called sierra and they said they got up to 89.5 with the 220. I have worked up to 87.5 with the 220, and 89 with the 210berger. Accuracy has been excellent, due to Kirby's work. I've got the berger shooting under 1" at 300, and the matchking right at 1" at 300. With some work on the seating depth I think I can bring them both down to about
.75 inches.