08-16-2023, 12:06 PM
stef1274 Wrote:Want to add something - hope it helps.
While temperature stability may be good, and temperature instability may be bad, make sure whether your powder is actually stable or unstable.
Test: I read an article a while ago, but I am unable to find it again now. Someone did a test with a number of SB extruded and DB ball powders. The way the guy did the test really looked solid to me. He cooled (with a 12V fridge) and heated (with a seedling heat mat) batches of each, loaded to the same CBTO and pressure rating. He also did some temp increments in between the extremes. Of course he worked with thermometers, good recordkeeping and good principles such as barrel management.
Result: both the SB stick and DB ball had some velocity response to temperature. The variations were quite linear, and relatively small for a hunter's requirements. I can't remember the exact variations, but the article blew away the idea that SB is oh so stable, and DB is unshootable. In some cases, variances on DB ball were actually smaller than its equivalent stick powder, most notably so in my favourite ball powder, Somchem S321.
After reading that article, I became very relaxed around this topic. I know I don't chase velocity, and rarely have loads > Pmax - 15%. I also hunt in areas where 80% of shots are below 150yds, and often at larger animals (read 'larger vital zones'). I only hunt in autumn and winter, and go to the range only early morning in summer, or midday in winter.
Summary: To answer the OP's question, yes, I think temp sensitivity is overblown. Not because it doesn't exist, but because the majority's skill level and requirements are insensitive to it. Also, don't just assume a powder to be stable or unstable just because someone said so. If you really must know, go and test it.
Stef:
Totally agree. I have put issued M-118 Special Ball into a bed of MRE heaters and got them so hot the shooter had to use gloves to put them in his M-24. Also put some on dry ice to cool them down. I did take temperatures using a thermometer. Can't remember the exact temps but there was about a hundred degree difference between the two. Shot them over a chronograph and found about a sixty fps difference. The powder was a ball powder. That's about one minute and yes, it can mean something but that something is caught up in a bunch of 'other things' and in my experience those other things tend to balance out any changes in velocity caused by powder temperatures.
I think some extruded powders of yesteryear had big problems with extremes of temperature but not so today.
LR-55