Powder

[dcederberg]

My question is, are any of you guys using IMR 7828 or Hodgdon US869 in your 300 ultra mags? I am using Retumbo but I cant ever find any and I have noticed that these two powders are usually available. I think Retumbo is supposed to give a little higher velocities but who cares if you cant go shoot.

Ceder

 

[MudRunner2005]

I use 7828 SSC in my 7mm STW, which is pretty similar in case capacity to the RUM's ( about 19 grains difference), and I am having excellent results with the heavier bullets. Very consistant pressure and velocities.

I use 7828 SSC from my .25-06 AI up to my .300 Ackley, and everything inbetween. It has been a great powder, so I've been stocking up on it.

 

[Engineering101]

dcederberg

The two powders you mentioned will work if you just want to shoot but there is a reason they are available such as temp sensitivity/extreme spread/pressure versus velocity. The IMR is probably the better of the two if you are stuck. If you are able to find some RL-33 give it a try. I'm guessing you will be glad you ran out of Retumbo as RL-33 seems to be the new king of the hill for the 300 RUM and 338 Edge.

I'm running the 210 Bergers at 3040 fps out of my 300 RUM, getting groups at 200 yards that average about 1.3 inches out of a factory barrel with no pressure signs and an ES of 10 fps. The flat primers indicate I'm over 60,000 psi but I probably have some room left. Eventually I will take it up until I do get some sticky bolt but I'm in no hurry. My nephew is getting the same 3040 fps out of his 338 Edge but with the 300 grain Berger OTM. That is crazy fast. That equates to 6,150 ft lbs which is way past even the 378 Weatherby.

If you can't find RL-33, Magnum works good and is emperature stable. That was my go to powder until I tried RL-33.

 

[dcederberg]

Thank you that is good info, I really hate to start over on load development but thats fun too. I sure wish that the reloading componants would start getting easier to get. Looks like this will be a good time for me to try heavier bullets and a different powder anyway.

Ceder

 

[Doublezranch]

I shoot 7828 ssc in both my 338 RUM and 7 RUM with excellent results. This powder has been very consistant. I see no reason not to use it. I do know that temperature sensitivity can been a issue, however I have never seen it. I have been wanting to try 33 in these two guns but 7828 ssc is making this very hard to change up what's not not broke.

 

[dcederberg]

Thanks for the reply, I have been searching the internet for RL33 or Retumbo and cant find either one. I can find 7828 though.

 

[Timber338]

I've gotten in the habit of checking a few different internet sites every morning when I'm up early drinking coffee. Gotten lucky the past couple weeks and found an 8 lb container of RL-33 and a 5 lb container of RL-22. I did see Retumbo available as well, but I do not personally use it. But all the powders were sold out again in less than an hour. That approach has worked for me, although you do have to be persistent. I'm still trying to find Federal GM215M primers, but no luck.

 

[MudRunner2005]

I shoot 7828 ssc in both my 338 RUM and 7 RUM with excellent results. This powder has been very consistant. I see no reason not to use it. I do know that temperature sensitivity can been a issue, however I have never seen it. I have been wanting to try 33 in these two guns but 7828 ssc is making this very hard to change up what's not not broke.

I haven't seen any temp-swing issues with 7828 SSC either. It has been so good, it has become my most commonly used powder in pretty much everything I own, except my .308 & 7mm-08. They still get healthy doses of Varget.