I had a great load with 180 Accubonds and 74.4 grains of RL-22 with CCI-250 primers out of the 300 Win Mag back in the late spring. It was shooting half inch groups at 300 yards and haven't used it. I had 6 rounds left after running out of powder. I picked up 3 pounds of RL-22 last week and worked up a load ( 3 round charges ) from 74.0 to 74.8 grains and it shot horrible at 200 yards (1.75 to 2 inch groups at least). So I shot the last 6 remaining from the last batch that used to shoot well. This batch also shot horrible. The air temp from the late spring is around 75 degrees if i remember. When I shot this morning, it was 50 degrees. Would this be enough to cause a temp swing? I hear RL-22 has about 1.5 fps with each degree change. Not sure if I should go back to square one with RL-22 or switch to a more temp stable powder like H4831 and H1000 with the 180's? Should I go to a hotter primer?

I would have never used that powder in the first place. H-1000 in a .300 Win Mag is too reliable, and temp stable.

Clean the barrel, shoot that load again, and see if it tightens up.

Going to give it a good cleaning with Bore Eliminator, check scope rings and bases and run a few more loads from 74 to 75.5 grains with RL-22 and see if that will work. If not, I'll switch to H1000

Try to use Hogdon extreme powders and you won't have to worry about temperature.

RL-23 would be another good temp stable powder to try

I have seen the same issue with RL22 and my 300 win mag. I switched to H1000 and never looked back!

I am leaning to skip RL-22 after reading others comments, going to try a ladder test with H-1000 at 300 yards and see what pops up. Thanks fellas. I'll keep ya posted soon as the wind dies down, it will be howling the next few days.

I run H4831 out of my winmag and never have temp issues and I hunt with it from likely teens to 50s. Never an issue. 200 ELD-x with 72.7.

Focus near book max.

I've tried them at medium powder charges, and they made dismal results. Get that case plum full of powder, and they shoot. Speaking of .300 Win Mag/ H-1000, and 7 Rem Mag/H-Retumbo here.

In the manner you are shooting for load work ups, no. I burned out a barrel shooting a 300 WM, 190 SMK and R22 powder, so I know it well. Yes, it will be temp sensitive. But it is also one of the most accurate powders in the 300 WM. So yes, it's a good choice.

What you are seeing is something changed from the last outing to now. 20-25 degrees isn't a lot. So, I'd be looking at the rifle, cleaning, fouling, or something else.

What was your speed with the .300 using the 180's when shooting good? Trying to find a node window. Thanks

P.S. If I could remember mine was around 3,165 fps.

Can't help you. I load for a friend's .300 Win Mag, with H-1000 and 210 gr Berger VLD-Hunting.

8 pound sledge!

I've burned a lot of rl23 and had awesome results in all temps.

How does the Berger 210VLD-H open up on deer and hogs out of a .300? I have some.

The friend that shoots that load contacts me every time he hits an animal with it. 250 pound snow at 500 yards dropped like a rock. Basically he bought the rifle and told me to load for it like it was my rifle, so I did.

Thanks Fireman and those who responded.