225 and 250s arent grouping with H1000 or Retumbo

[Ultramag45]

Hey guys I have been sending alot of rounds downrange from my Defensive edge 338 RUM...I have a couple really good loads with RL22 and RL25..shooting the 225 gr accubond.1/2moa..Decided to change to H1000 and Retumbo for temp stability..wow best I can come up with is 1 inch groups at 100...tried increments in .5 grains...and several different seating depths... strange grouping..2 touching and 1 an inch away.atleast 10 different loads..all loads have the same pattern...tried the 250s...same thing...went back to rl 22 and bughole groups..same with Rl 25....I have a bunch of this powder and want to make it shoot...getting awesome ES of 8 and under and SD of 6 and under...very strange...I then loaded an accuracy load that Shawn Carlock sent with the gun..86 gr of H1000 300 smk...it shoot a bughole....loaded some 300 accubonds, they to were in one hole.....cant figure out why these powders wont shoot the lighter bullets out of this gun...I usually shoot the 225s as i am primarilyHunt highcountrty mule deer...any thoughts about why this is happening...best load has been 100 gr of h1000...fed 215 primer seated at 3.70 Oal...played and played with too many getting a little expensive...Shooting 96 gr of rl 25 consistantly .3 to .5 moa....Am I missing something, thanks guysgun)

 

[Franklin]

My 338RUM shoots bug holes with 100grs of H1000 behind the 225accubond and federal 215M, only difference is my coal is 3.76. I think H1000 and retumbo are a little on the slow side though, for a 225gr bullet. I'd try H4831 and see what it does, if you want to stay with a temp stable powder.

 

[royinidaho]

Regardless of how much of what powder one has on hand the goal is to get the best performance which in my mind means a combination of energy and accuracy.

Speed isn't all that important.

If she shoots bug holes w/300 gr offerings that's about as good as it gets.

My go to load in the RUM is 300 Hybrid well into the rifling ahead of 101.5 gr 50 BMG. Weird but effective. MV is right at 2735 with enviable ES & SD.

 

[tim jurczak]

This effect has plagued me and my 6.5 STW. WC 872 and H50BMG will fling shots and break my hunting confidence. So I use fast (realitively) powders, Retumbo, RL25, and 7828 and get little triangle shaped groups. Hard on brass but trust worthy. Actually Retumbo seems to be in what appears to a gaping hole between the burn speeds of the 7828,h1000, RL25's and then the 872, 869, and h50bmg. Retumbo also gives good groups without wrecking brass seems to work well with my shortish 26" barrel. I believe barrel length is the reason one has trouble sometimes with a powder that by all accounts should be ideal.

I hope to learn more from this thread.


Tim