poweder problems

[tmmcampbell]

Hi, just started reloading for a 7mm ultra. The rifle is the sendero with the barrel sent in to christenson arms to lighten it up. I loaded it up with 140 gr nos part, 92.5 gr of reloader 25. velosity was around 3370 and it shot quite well. This was at about 72 deg. day. I took the same load out and shot a 98 deg. day. There were pressure signs on all the brass and the bolt handle was sticky. It also sprayed bullets in about 6 inches.

Is reloader 25 that temp sensitive? I am looking to try h4831. However a max load is only 88 gr. with this much space in my shell will I have problems with pressure excursions. I have been told if there are large spaces of air in the case you could have problems??

What do you guys think? Thanks

[liltank]

I'm kind of in the same boat as you with my rifle. I don't seem to be getting the same grouping abilities as with powders with less capacities. I have a load using H1000 that is almost compressed and shoots wonderfully. I then tried shooting RL17 and with even a ten degree temp change, the rifle is shooting erratic pressure sign changes and groupings. The nice thing is that I am getting the speeds I want. The H1000 load shoots considerably slower, but it group at .5MOA where the RL17 is currently shooting .733.

I hope this helps.

Tank

[winmagman]

IMHO, its not so much the 10 or 20 degree swing but where that swing occurs. For example 40 degrees to 60 degrees will most likely have a minimal effect on your load, but for some reason 70 degrees to 90 degrees can get you into big trouble. I don't know why but it seems like once you get over 80 degrees it takes much less of a temp change to radically effect a load.

That of coarse is a generalization, when and where the changes start to happen vary with powder type and brand.

Chris