Home Forums Hunting & Shooting Ask The Gunwriters JB, have you tested IMR 4350 temp sensitivity?

I enjoy reading your temperature sensitivity powder tests and I don't recall reading anything on IMR 4350. I use it it in a 6mm rem and it seem to work well in that rifle, and it is available. I know that it is a little faster than H 4350, but I can't find that powder to try. Have you done a cold / hot temperature test with IMR?

I'd love to see a comprehensive (as much as possible) test across powders for temp sensitivity. I shoot across a lot of temps from summer with mid-90's (more volume shooting) to last week hunting in mid-teens (less volume, mainly hunting)...and all seasons in between. I mainly shoot H powders but wonder how much it matters.

There were two IMR4350 cold-weather tests included in the long list in my recent HANDLOADER article on temperature sensitivity, one with the .30-06 and 165-grain bullets, and one with the .375 H&H and 300-grain bullets. In both tests IMR4350 lost some velocity, though considerably more in the .30-06 load.

In general, the traditional IMR rifle powders like IMR4895 and IMR4350 are somewhat temperature sensitive, but not nearly as much as some other powders, especially older sphericals. Plus, as I pointed out in the article, temp sensitivity varies with the specific cartridge and bullet weight. This is true even with some of today's more temp-resistant powders, though the effect is smaller.

After the article appeared, the head guy at one of the major powder companies wrote me a complimentary e-mail, noting that in their tests they've also found temp resistance also depends a lot on powder compression. More compression usually results in less velocity loss in cold--which is probably why the .375 H&H load loses less than the .30-06 load.

He also said the specific primer can make a measurable difference in cold-resistance. Their lab tends to use Winchester large-rifle primers and CCI small-rifle benchrest primers.

Another item I noted in the article is that velocity loss in cold sometimes doesn't result in any measureable change in point of impact at 100 yards, but sometimes does. It depends on the individual rifle as well as the load. The .375 IMR4350 load didn't change POI at all, I would guess partly because the velocity loss was less than 50 fps, and the .375's barrel has a relatively heavy countour. The .30-06 load lost about 75 fps, and POI at 100 yards ROSE two inches. Which brings us to the other important point made in the article: If POI changes at different temperatures, it can be in any direction.

Very interesting John, especially for typical hunting rifles as opposed to typical heavy barreled long range setups.

What I've found, while doing cold-testing over the past 25+ years, is that rifles which change POI noticeably with different powder charges (as when working up a handload) also tend to change POI when muzzle velocity drops in cold weather. But not always, which is why there's no "rule" about what will happen, and the only way to find out in any rifle is to shoot it in cold weather.

John, pardon the ignorance but what defines "cold weather, below 32F?

I do my tests at 70 and 0 Fahrenheit--or as close as Montana weather allows me to--with both rifles and ammo chilled overnight. Zero was chosen because I'd noticed some wonky results over the years in temperatures somewhere around it, and to make the tests consistent. Plus, in my part of Montana we can usually count on getting some days down around zero each winter, but not always much colder.

I have, however, tested ammo at various other temperatures. Generally, from about 25-30 degrees to the mid-80's there's not enough change in velocity or POI to worry about with any powder, especially for hunting big game. The real problems are almost all encountered from about 10 degrees and lower, and from the high 80's up, but with many of today's newer powders neither is a real problem.

Thanks, John. No worries on my end then

While hunting Mule deer north of Winifred, MT temperature sensitivity came into play.

Several of my relatives who own ranch land in the area and I set up to push out some coulees that led down to the Missouri. My cousin and I were at the head of a coulee that went north and merged with another coulee from the West. It was a crisp morning with temps in the teens. We were waiting 45 minutes for the standers to get set when suddenly a huge buck and two does emerged on a switch back at about 250 yards out. (later ranged at 285 yards).

I was already tagged out so Cuz went prone and laid his Winchester M 70 Featherweight 257 Roberts that was loaded with 100 grain Hornady InterLock/IMR 4350 over his pack. He settled in and touched off a shot and I saw the bullet hit underneath with my binoculars. The buck vanished and it was quiet, Cuz looked over to me and said: "Damn powder temperature sensitivity". I about split a gut laughing.

This is great info and thanks for answering my question. I think I had an old age moment because I have the issue at home but forgot about it! Thanks again.

Thanks M D:

NOT to toot my own horn, well not too much anyway, but I found THIS....from your post above....

>>>>[/b]"He also said the specific primer can make a measurable difference in cold-resistance. Their lab tends to use Winchester large-rifle primers and CCI small-rifle benchrest primers." [b]


to be the case BACK in the 80s. I ran my test with quite a few rifles in quite a few calibers, using different powders, using DIFFERENT primers. < I have my notes and can post them....outdated as they are>

I was comparing B Hagel's tests to MY OWN. I was comparing vel at temps @ 75*-------down to @ 30*. Thirty degrees is/was close to the average temp I hunt here in the South.

During my testing I used WW LR (the WW L R M weren't out), CCI LR & LR M , Rem 9 1/2 & 9 1/2 M. I did not have access to Federal primers at all.

Mr. Hagel wrote off temp. sensitive to POWDERS.... well I found the POWDERS were MORE consistent THAN primers.
To verify that, I RE ran my test using ALL W W primers.

Yet some powders DO show more sensitivity than others. That's probably MORE true today than 30 odd yrs. ago.

PER the OP - I have found IMR 4350 to be NOT SO BAD with high density charges & W W primers.


Jerry

My experimentation has shown that those powders that don't change much are advertised as such. Powders such as Hodgdon Extremes (Varget, H4350, H322, Benchmark are the ones I've tried), some newer Alliant powders (16 and 26 anyway) and IMR 8208 do exceptional down to single digits. Regular ball powders (AA2230, AA2260, TAC, Leverevolution, 2000-MR) tend to lose 90-100 FPS while the more stable powders remain the same or lose perhaps 10-20 fps. And as JB says, different cartridges do seem to matter. RL17 in my 338-06 lost very little while it lost more in the 6.5 Creedmoor (I think...need to check notes). I've tried powders in the 338 Federal, 308, 338-06 and 6.5 Creedmoor. Unfortunately I can't add to the IMR4350 discussion other than to link to some info from Hodgdon.

https://www.hodgdon.com/extreme-rifle-powders/

jerry,

One of the major flaws in Hagel's tests was only freezing the ammo, then testing it in rifles at normal temperatures. This does NOT usually reproduce what happens when everything's at the ambient outside temperature, as it is in hunting. Any primer comparisons under those test conditions are pretty much worthless.

prm,

I've found TAC to lose nothing in cold temps in the .223 Remington--which is essentially what it was designed for. And there are quite a few powders like that, very cold-resistant in some rounds, not much in others. Big Game, for instance, is very good in the 7x57, .30-06 and other cartridges with similar bore-to-powder capacity.

I'm going to be putting that article in GUN GACK 2, and adding a bunch of other information that was impossible to put in a magazine article due to space restrictions. We hope to have GG2 out by early fall.

Thanks JB, Yes, cartridge does matter. I haven't done this enough to quantify it in any way, or even understand it, but I did see signs of that with RL17 and the 338-06 and 6.5 Creedmoor. Edit: all my TAC readings were from a 338 Fed.

Yes, M D we have talked about that before.

I was able to leave my ammo in an OPEN cardboard box on my carport - not garage.

I left the rifles locked up in my Pickup. So both the ammo & rifles were at the same 'ambient' (grin) temps.


Jerry

I was just noting why Hagel's tests were flawed, not yours!

I've had IMR4350 in a 30-06 AI with a 200gr Partition average ~80 fps loss from 80 degrees to 5-10 degrees but shoot to the same POI.

I have a friend who says that POI may be markedly different at 300 yds and beyond though.

Yes I understood. No Harm No Foul. I added my comments for those who might be interested.

Thanks

Jerry

John,

Any info on the temp sensitivity of AR-Comp & IMR-8208 XBR?

Thanks.

MM