I am having some trouble with velocity deviations of around 100fps with RL22 in a 300RUM. The load is a published load with max velocity of around 3290. Pressure signs are fine and most of the loads chrono very consistently. The loads that blow my mind are down around 3200 which seems like alot to me. When this happens, of course, the shot pulls out of the group. Does this sound like a primer problem or do you guys think I might have a scale problem. My scale is a RCBS 505. (Not the nicest one I know) and the primers are Fed. 215. I am going to try the 215 match primers. If that doesn't help I am going to buy a new scale. Any other ideas....brass, powder, etc?)

Are all your cases identical as far as case prep, brand, powder charge, primer brand, and bullet seating? Try a different powder like Ram Shot Magnum. Go tohttp://www.ramshot.com/powders/

300RUM, can be tough. Problem is probably the cases. I had such hard time with remington brass. Always had a thick side. I ended up buying several hundred pieces of federal brass. And they performed much better, but after 3-4 firings, wouldn't hold primer well. I don't load for the RUM anymore, so I sold all the brass. Here is where you can get some more. I tried everything and ended up culling the rem brass based off of neck thickness variance.

http://www.dlsports.com/fed_300_rum_brass.html

My brother and I ran into the same issue with his 300 RUM and RL22. I tried just about everything. I even tried the 215M primers thinkin match primers might help. I soon gave up, my bro just has to deal with it. I feel bad but dont know what to do

Out of the 3 RUM's I owned, I don't think I ever got the extreame spreads to go below 40fps. And some as high as 100fps. H1000 and IMR4350seemed to be the most consistent. I tried IMR4350, RL22, IMR7828, H1000, RL25, Retumbo, and Norma MRP. But I had good accuracy out of most of them. Even RL22 loads with high spreads would produce under 1.5MOA out to 500 yards.

I am sure stubble will come on here. Maybe he can tell his spreads.

This problem could vey well be due to a combination of factors, the most significant of which are probably powder type and the .300 RUM's large case volume. It is likely that RL-22 behaves a littleerratically when used in such an overbore case at less than 100% + loading density. Both the .300 RUM and .300 Weatherby just have a bit too much case capacity to work well with some powders. You usually can find one that will do better than a variation as high as 100 FPS between shots, but sometmes it is a real PITA to do so. I have heard of cartridgesbeing so overbore that the barrel was shot out before a good consistent load was found!

One more thing to add to eld's post. RL22, loves higher pressure for some reason. At starting loads alot of times, I see crazy accuracy and velocity variations. But for some reason in cartridges like the 300win mag, it likes to be screamin hot. Where I notice powders like H1000 likes midrange.

Try some RL 19, it will load close to 100% capicity, like BC said they like being full or close to full which ends up screeming. My 300 Win Mag liked 77.8 of RL22 which is .2 from max and was moving at 3275 fps.

This gun has been a pill to begin with. It's a Model 70 classic stainless. I love the gun but I think the barrel is too whippy for the cartride. The thing will shoot lights out one session and 3" groups the next. It seems to prefer RL22 as opposed to RL25 for some reason. I have also tried Retumbo but haven't really wrung it out. Aren't the Hodgon Extreme powders supposed to be more consistent?

Yes, the Hodgdon extremes are supposed to give more consistency despite varying factors like temperature etc.