Home Forums Reloading Big Game Rifles IMR4350 in 300WSM Temp Stability/Sensitivity test

bsa,

The "efficiency" of the .300 WSM was an advertising line Winchester came up with when it was first introduced, implying it got more velocity out of a given amount of powder room than "conventional" cases. This wasn';t true, but it does burn powder more consistently, resulting in smaller variations in pressure and velocity, which may be why it worked so well in this instance.

But it also may simply be a coincidence. As I noted above, many powders are more temperature-consistent in specific applications, which aren't necessarily predictable.

All I used in my 300WSM was IMR4350 and at 20-degrees my average was 2900 +/- and at 80 was 2950 +/-. Resulted in about an inch at 300-yards.

Was not a concern to me since the accuracy was still good at both conditions.

I use a lot of it 25 06 up to 7 mags. Kills cshit out of deer and pigs. 50 fps isn't going to make any difference on game. 4350 ain't the powder to get the fastest speeds, but it's accurate in every thing I have ever tried it in. The guys on my deer lease say 4350 is an old mans powder.

JB-
Based on my reviews of NWS data from MT this winter, you should have lots of opportunities for cold wx testing...LOL!

Yeah, I've already run two tests, with five rifles each time, and may run another.

You picked a good winter to head south!

IMR 4350 is hard to beat, old reliable

I always say.... When all else fails, try IMR 4350.

That's an interesting way to look at it. I had a similar experience with RL17. In my 338-06 it performed very well, while in the 6.5 Creedmoor it lost quite a bit of velocity going from 70 to 12 deg.

Any results you can share? I'd like to see any RL16 results. I just tested a 6.5 CM load that did exceptionally well. But with such a small data sample it's nice to see additional results. I don't know why, but I am oddly fascinated with this.

I haven't even seen RL-16 anywhere, and that's not just local stores but the websites I primarily order from.

The results will be published in HANDLOADER magazine sometime this year, though I also have some more hot-weather tests to do, so probably not until fall.

I doubt case capacity has any consistent bearing on cold-resistance. Instead my tests have indicated that powder NOT specifically suggested or designed as temp-resistant will vary considerably in results in various applications, with no real pattern.

Thanks, look forward to your results. I just picked up another 3 lbs from MidSouth Shooter Supply. Seems to be really good in the 6.5 CM.

There can't be _no_ pattern or consistency to temperature resistance, otherwise one wouldn't be able to optimize a powder for a specific cartridge-bullet weight combo. Neither would Denton likely see worse temp-resistance from Varget in his 223 than surplus military ammo, but see excellent temp-resistance from Varget in his 308 (see his paper, Pressure Factors: How Temperature, Powder, and Primer Affect Pressure). There may well be general temp-resistance characteristics one can 'apply' to any powder, but it seems clear that there's more engineering to it than that.

It has always struck me as rather curious the disparity of results from one internet shooter/hunter to another, though, when supposedly using the same powder in the same cartridge.

IMR 4350 is generally the first powder I try, if it's listed in the book for that cartridge/bullet combo. I've just seen different results than the OP suggests. However I've never tried it in the 300WSM, since H4350 always seemed to get the nod from the guys here...

I always use temperature insensitive or cold tolerant powder in all my big game rifles. January temps in western mountains can vary dramatically. Last weeks hunt was pretty mundane with temperature swings - but we just missed out on a big one.
Our Saturday (1-7) morning departure was a drafty -30 on the truck reading.
By Monday, it was 43* and raining! Now for my self-imposed limit of 399 yards,
a loss in some velocity may not mean much but I don't want any surprises.

John,

I'm fortunate to have a gun range where I can drive up beside the last bench and string my Oehler into the cab.

I also spoke to a Hodgdon tech this afternoon about IMR7977 and it's temp stability. He made note of different loads having different respones to temperature, but he characterized the Enduron powders as having similar temp stability to the Extreme powders.

I have only shot IMR7977 a small amount, but I can say it burns MUCH cleaner than H4831 in my 243's, 270's and a 30-06AI.

Casey

That's my thinking too!


Casey

I'm going to try to keep H4350, H4831SC and Varget as my primary powders. If I am vigilant, I think I can keep enough on hand. An 8#er may last 4 years or so which may be about enough.