Temp sensitivity in RE10x

[Its204fast]

When I first started loading I started with .204 Ruger, 32gn Sierra Blitz King. always used BR4 primers, and a charge in the area of 26gn of Alliant Re10x.

It was a great load (5 shots under 0.5" at 200 yds. on sandbags.) It brought my confidence up tremendously. I started shooting around the end of fall temps in the 60° range through the winter temps down as low as the mid 30°'s. I joined my first shooting range and the guys were really impressed by a newcomer.
Then it started to warm up as spring approached and my groups started to spread, I went back to the 100yd range and it was grouping the size of a solo cup. I was about to pull my hair out, I had another guy shoot it and same result. He told me that Alliant powders are temp sensitive and it was due to the heat. so I switched to Benchmark and it does good but I have never been able to achieve the same group as before with it no matter how I adjust the charge, seating depth, case length. I'm now shooting a 0.8-1.0" group at 200yds but it doesn't matter if it's 25° or 105°

any suggestions on achieving a better group with Benchmark?

 

[Seabeeken]

Some of their powders are temp sensitive and some are not. Since you tried to adjust the charge weight and COL and going back to cold temps, I have to ask how many rounds thru it since the last cleaning? Large powder charge, small bore and high speed gets em dirty quick. Check it with a bore scope if you can. It might be enlightening. Years ago, the 220 Swift had a reputation as a barrel burner but often it was just a badly fouled bore. Once cleaned the accuracy came back. Hope this helps

 

[Doom2]

You might try dropping the RL10 charge back 1.5 grains and working the load back up.

A note on cleaning mentioned above. Some powders don't play well when they are shot without cleaning the rifle in between.

 

[Its204fast]

Some of their powders are temp sensitive and some are not. Since you tried to adjust the charge weight and COL and going back to cold temps, I have to ask how many rounds thru it since the last cleaning? Large powder charge, small bore and high speed gets em dirty quick. Check it with a bore scope if you can. It might be enlightening. Years ago, the 220 Swift had a reputation as a barrel burner but often it was just a badly fouled bore. Once cleaned the accuracy came back. Hope this helps

It's been a few years since I moved away from RE10x but I rarely went over 20 rounds without cleaning. I'm not so particular now. I know with the benchmark its going to shoot the same dirty or clean. gun has somewhere around 1200 rounds through it.

 

[Its204fast]

You might try dropping the RL10 charge back 1.5 grains and working the load back up.

A note on cleaning mentioned above. Some powders don't play well when they are shot without cleaning the rifle in between.

I also have a decent load worked up with 26gn varmint grenades over Ramshot Xterminator that groups about the same.