I have been reloading for my .300 RUM for about a year now. I have found that it is an awesome shooter when it gets the load it likes. For a factory barrel it never stops amazing me. Below is the picture of the gun and some of my best 3 shot groups. I have also loaded a dozen or more loads that easily shoot under .6" at 100 yards. I have not chronographed any of the loads listed below, but I will this Fall and I will also be reaching out to 1000+ yards with it.


Here is the rifle, a Remington 700 Sendero SFII. It is stock except for a Timney trigger and some stock cleaning up. It is wearing a Bushnell Elite 6500 Tactical scope in 4.5-30X50mm and mounted with Weaver rings on a 20 MOA Weaver base.


This group is 89.5 grains of Retumbo under a 230 grain Berger Hybrid and seated .030" off the lands. Measures .325 inches if you can't read my sloppy handwriting.


This group is 86.0 grains of RL25 under a 210 grain Berger Target seated .030" off the lands. The group measures .245 inches.


This group is 94.0 grains of RL 33 under a 230 grain Berger Hybrid seated .030" off the lands. The group measure .389".


This is my favorite load. It is 97.0 grains of H50BMG under a 230 grain Berger Hybrid also seated .030" off the lands. The group measures .217" and had 2 bullets through the same hole. If I was a better shot or the gun was in a vise, I have no doubt it would have been just one hole.

10 shots out of a RUM (I only have the 7mm), without fatigue getting to you before the weather conditions changed, would be impressive in itself.

I have the 300 RSAUM. I agree with shooting more than 10 rounds at a time is not a lot of fun. I think my max I put myself through was 30. At that point, I was just slinging lead. Not really hitting anything. Getting ready to load up some more bullets for it soon. Maybe Ill post some pics.

Um, yea, if you don't start pulliing flyers after 4-5 rounds you are pretty damn good.  Nice rifle.

Exactly. The gun has never made me flinch, but shooting even 5 shot groups is not productive when testing several different types of loads in these big magnums. It is crazy expensive and the factory barrel would get so hot that I think accuracy would decline rapidly after a few groups. Once I find my perfect load I will shoot a 5 shot to note any change in group size.