IMR-4350 Temperature Sensitivity?

RiverRider · Dec 20, 2012

I think the only way to know for sure about temperature sensitivity is to load up some ammo with powder in question, say 40 rounds or so---all at the same time---and then shoot half of it over a chronograph in very cold weather and do the same with the remainder of the ammo during very hot weather. Then all you have to do is wonder whether the temps were affecting the chronograph.

You can't win, but you have to play.

Oldtrader3 · Dec 20, 2012

Go to the site: Shootingsoftware.com. Read about powder and temperature distribution of IMR 4350 versus H-4350. I summary, IMR 4350 only shows a temperaure variation of a few hundred PSI or about 2/10's that of H-4350 in terms of PSI versus temperature variations.

PJGunner · Dec 21, 2012

Thee last set of loads I did was with my Chargemaster 1500. I did periodically check the thrown charge with my RCBS balance beam scale and they were spot on, plus or minus 1/10 grain. I don't seem to have this problem with other cartridges though, just in the 30-06. As far as pressures signs, stiff bolt lift, ejector marks on the case heads. I could understand it if it was just in one rifle but in three? Oh well, they do just fine with H4831 and 180 gr. bullets.
FWIW, I did give it some thought and yesterday did a side by side test of the Chargemaster and checking with the balance beam scale plus another digital scale by RCBS, Each scale read within 1/10 gr. of each other as before. I ran 30 charges over the scales for the test.
I also have a small batch of bullets of known weight I use as check weights and they all gave the proper weights so I think my scales are not the problem. The powder is maybe 5 years old at the most and I still have powder I bought back in 1973 that works just fine today.
Right now I'm getting loads done up for my .35 Whelen in preperation for an elk hunt in about two and a half weeks. The rifle was in the shop for some work and I have to get it sighted in. I've also loaded up a test series with the 225 gr. Accubonds and Partions plus a few ballistic Tips I came across at a gun show. Not enough of those to be meaningful but I'll use them for practice.
Paul B.