IMR-4350 Temperature Sensitivity?

How temp sensitive is this powder?

I'm doing my first load development process with this powder currently and I'm curious if I need to back down my charge weight when the temperatures increases?

How much would I need to back it down if at all?

Would it be worth it to just switch to H4350 and start my load development over?

Here in Oklahoma are temp varies pretty drastically through the year from 100+ degrees in the summer months to as low at 20 degrees in the winter.

I currently do not have a chronograph as I am new handloader.


Basically I'm just curious as to the loads I'm developing now in winter months are going to be dangerous when the temps start going up in the spring.

I'm just curious as to the loads I'm developing now in winter months are going to be dangerous when the temps start going up in the spring.

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The simple answer is "Maybe." How much are you tickling the dragon's tail in mid-winter. Truthfully, if you are not loading "hot," and if the temperature isn't below about 20 F, I wouldn't be too concerned when the temperatures are running in the 90s. I grew up in SE KS, and I do understand the temperature swings in that area. Still, provided I knew I wasn't loading hot, it wouldn't be a terrible concern to me. This is, however, an excellent time to push a chronograph, as it will permit you to be cognizant of how close to maximum velocities you are coming (velocity being an imperfect, though reasonable indicator of pressure). I might suggest that if you work up a load, it would be worthwhile to do a simple retest in hot weather. I wouldn't, however, anticipate serious complications under normal conditions.

Published handloads from bullet makers, their latest versions (not Q/L near max data) are safe with IMR4350 whether winter or spring.

IMR4350 is a single based powder, as is H4350, all powders are a bit temp sensative (yes even the extreme powders, the moniker is a marketing ploy) double based powders are more temp sensative due to the addition of nitroglycerin into the make-up. book max loads are safe with 4350 if the temp is below 120F.
in other words don't lay them on the dash in the summer.
RR

There are some very interesting things to read in this thread:

viewtopic.php?t=11441

One of the interesting things is my own comment in regards to Ramshot powders, which I made in reliance on the writings of John Barsness. I think JB is one of the best rifle writers wielding a keyboard these days, but I am not so sure about his assertions following a conversation I had with a Western Powders ballistician a couple of years ago.

I think I'm just going to have to run an experiment of my own to see what I can see.

look at the label of listed ingredients on the back of your powder container, if it says it contains nitrocellulouse its a single base powder and less likely to be affected by tempature, if it contains nitrocellulose and nitroglycerine its a doublebased powder and will be more temp. sensative.
ya hear alot about reloader 22 being temp sensative, it is a double based powder, but my main problem with it is lot to lot varience, I can deal with temp sensativity.
RR

YES! Provided you are loading within book specs you will have no problem. Accuracy won't vary much whatsoever. If its -5 degrees F or 105 degrees F it will shoot fine. Again provided you are within book load data no worries.

here is a quick read on powder temp. stability . it is question # 7 . Jim


http://www.accuratepowder.com/faq/

Like I said, IMR4350 is fine when one stays at or below published max loads whether in cold or hot weather. Thanks for the link you gave so people can read it and be aware of the real truth concerning the matter.

I do most of my load work ups in the summer which here in terribbly torrid Tucson can get quite hot. It's not too unusual to be shooting on days where it as high as 110 degrees. :shock: Yes, you can get used to it. Which brings up the point of temperature sensitivity of IMR4350. I have several rifles chambered to the 30-06 including a custom mauser, another mauser that's strictly stock except for the Butler Creek stock and two Remington 700's one a BDL, the other a Classic.
I have never been able to get anywhere near the book max load in any of those rifles in the heat of summer which is not too surprising but during this time of year when the temps are running in the 60 to 65 degree range, I still can't come anywhere near a book max load without potentially serious pressure signs. :?: The custom rifle should show slightly less pressure as it has a 1 in 12" twist rather than the more normal 1 in 10" but it fares no differently in velocity and pressure signs from the other rifles.
Ball type powders are supposed to be more temp sensitive but for years I used them in several cartridges, mostly the .270 Win. and .300 Win. mag. (WMR) and .308, (W748 and W760) with none of the problems I had with IMR 4350.
With all I've heard about how great IMR4350 is supposed to be in the 30-06, based on those 4 rifles it hasn't been all that great for me.I just picked up some H4350 and I'll be giving that one a try. Dunno if that shed any light on the question of just helped confustiagte the issue. :roll: :lol: :lol:
Paul B.

Twist will have an insignificant impact on pressure. I should imagine that chamber dimensions and throat depth are more likely culprits in the inability to witness maximums in your case, Paul.

If find in several guns that IMR4350 gives smaller groups than the Hodgdon's powders. Given temp extremes (5 to 95 F), the IMR version still shoots closer to the point of aim as a group at 100 yards.

In other words, the temp is less important than finding the most consistent powder for me.

I have been using IMR 4350 for well over 30 years and I don't think there is a real bad problem with temperature change. I live in a area that has drastic temperature changes from -40 to plus 35
I have been Whitetail hunting that at the start of the season it is plus 20 around 70f and by the end of the week it is -20. I do not notice a lot of difference at 200 yards.

Blessings,
Dan

All gun powders are temperature sensitive. Charles Gas Laws are in effect for powder burning as well. Pressure is a function of temperature with any gas. You have to realise that any ambient temperature has to be compensated for or the temperature is slightly less in the case of low ambient temperatures. You are always adding the burning pressure/temperature curve to the ambient.

I have been using IMR 4350 since January 1964, almost 50 years. When I used to hunt in Canada, Wyoming and the rocky mountain states during late season and the temperature were close to zero *F, I always used a magnum primer instead or a standard large rifle primer to compensate. I do not even do that anymore becuase I do not think that there is enough difference in velocity, and/or bullet drop, to matter out to 300 yards.

I saw some test data of temperature resistant H4350 against IMR 4350 and the pressure changes at 20 *F were not that much different and in fact IMR 4350 changed about 800 psi less than H4350 pressure did at that temperature. Given this data, I would not worry about it.

PJGunner":p1kdzaj0 said:

I do most of my load work ups in the summer which here in terribbly torrid Tucson can get quite hot. It's not too unusual to be shooting on days where it as high as 110 degrees. :shock: Yes, you can get used to it. Which brings up the point of temperature sensitivity of IMR4350. I have several rifles chambered to the 30-06 including a custom mauser, another mauser that's strictly stock except for the Butler Creek stock and two Remington 700's one a BDL, the other a Classic.
I have never been able to get anywhere near the book max load in any of those rifles in the heat of summer which is not too surprising but during this time of year when the temps are running in the 60 to 65 degree range, I still can't come anywhere near a book max load without potentially serious pressure signs. :?: The custom rifle should show slightly less pressure as it has a 1 in 12" twist rather than the more normal 1 in 10" but it fares no differently in velocity and pressure signs from the other rifles.
Ball type powders are supposed to be more temp sensitive but for years I used them in several cartridges, mostly the .270 Win. and .300 Win. mag. (WMR) and .308, (W748 and W760) with none of the problems I had with IMR 4350.
With all I've heard about how great IMR4350 is supposed to be in the 30-06, based on those 4 rifles it hasn't been all that great for me.I just picked up some H4350 and I'll be giving that one a try. Dunno if that shed any light on the question of just helped confustiagte the issue. :roll: :lol: :lol:
Paul B.

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PJ,
I don't doubt what you are saying is happening but I would look for other reasons than the powder. I've loaded IMR 4350 in about everything one can think of at some point and never once had an issue due to the atmospheric pressure. Not once.

I don't doubt your ability to load ammo but something seems to be wrong with something. This is happening for you across multiple platforms so the odds that they all have a tight chamber isn't likely. It is also happening for you in extreme heat or moderate temps. I would say something is going on at the load bench.

I never had an issue with it.
That said the extreme powders do offer me more stability.

300WSM":394tqdek said:

PJGunner":394tqdek said:

I do most of my load work ups in the summer which here in terribbly torrid Tucson can get quite hot. It's not too unusual to be shooting on days where it as high as 110 degrees. :shock: Yes, you can get used to it. Which brings up the point of temperature sensitivity of IMR4350. I have several rifles chambered to the 30-06 including a custom mauser, another mauser that's strictly stock except for the Butler Creek stock and two Remington 700's one a BDL, the other a Classic.
I have never been able to get anywhere near the book max load in any of those rifles in the heat of summer which is not too surprising but during this time of year when the temps are running in the 60 to 65 degree range, I still can't come anywhere near a book max load without potentially serious pressure signs. :?: The custom rifle should show slightly less pressure as it has a 1 in 12" twist rather than the more normal 1 in 10" but it fares no differently in velocity and pressure signs from the other rifles.
Ball type powders are supposed to be more temp sensitive but for years I used them in several cartridges, mostly the .270 Win. and .300 Win. mag. (WMR) and .308, (W748 and W760) with none of the problems I had with IMR 4350.
With all I've heard about how great IMR4350 is supposed to be in the 30-06, based on those 4 rifles it hasn't been all that great for me.I just picked up some H4350 and I'll be giving that one a try. Dunno if that shed any light on the question of just helped confustiagte the issue. :roll: :lol: :lol:
Paul B.

Click to expand...

PJ,
I don't doubt what you are saying is happening but I would look for other reasons than the powder. I've loaded IMR 4350 in about everything one can think of at some point and never once had an issue due to the atmospheric pressure. Not once.

I don't doubt your ability to load ammo but something seems to be wrong with something. This is happening for you across multiple platforms so the odds that they all have a tight chamber isn't likely. It is also happening for you in extreme heat or moderate temps. I would say something is going on at the load bench.

Click to expand...

I have to agree somewhat with what you say. Three of the rifles in question are just commercial gun, a couple of Remington M700s (BDL and Classic) and the other a J.C. Higgins M50 given to me by a late friend. The fourth rifle is on a commercial FN Mauser action and was built by the late Cal Albright a more of a hobby gunsmith that had a good reputation in the Reno and Winnemucca Nevada area for his fine metal work. Where I'm running into difficulty is I'm getting pressure signs with out velocity and nowhere near the top charges in any manual. :?: Definitely has me scratching my head. I've been reloading since 1954 and even did some commercial custom handloading for people back in the 1970s.
Right now I'm just a bit too busy to mess with it as I'm getting stuff ready for an upcoming cow elk hunt. My freezer is screaming that's it's too empty. :lol:
Paul B.

Paul, I am one of those people who has been loading IMR 4350 for 50 years and loading up to the book and over by a couple of grains on several loads including, .257 Roberts, .280 Rem, .30-06, and even the .340 Weatherby. I have never had an issue. I certainly do not doubt that you have an issue. I just can't fathom what it might be on the basis of an internet communication. Without getting physically involved, I do not know what the issue is with your loads?

PJ,

Please don't dismiss this next thing as just a "no way"....

How is your scale? When I say how I don't mean the type or the maker of it, but rather is it giving you a true reading or measurement...every time all the time. I once had a lyman digital scale that would read one thing and the next time weighing the exact same thing it would read something else. Luckily an accident never happened and I smashed that scale so nobody, even a garbage picker would ever use it....... but it can happen. I had a friend who used a mechanical scale and the timing..balance if you will.....got out of whack. That can happen. I'm not saying that is happening here but it might be.

IMR 4350 is a powder that i tell everyone they have to have for the bench. It is a powder that can be counted on to work good. It might not give you the best results as something else but in everything I ever loaded with, it was atleast acceptable accuracy, velocity with no pressure signs no matter the weather.


Lastly, when you say too high of pressure, how are you determining this too high pressure. Again I don't doubt your experience in detecting the tell tail signs of high pressure but what are you really experiencing here that is making you say such. It very well might be something simple and has nothing to do with powder whatsoever. Nothing can be more frustrating than chasing one's tail on something and I would love to help you figure this out...because IMR 4350 is such a staple that can be counted upon to provide good shooting with no pressure in such a wide range of applications.

PJ,
The questions 300WSM posed are mine as well. Just think there must be something going on here besides the powder. Is the IMR 4350 all from the same lot? Was it always stored properly?
How old is it?

My old 5-0-5 scale is good, but won't tolerate any dust or crud at all on the 'bearings' or the knife edges. It will give false sort of hung up readings in that case. I still bump it up and down a couple times every weighing, just to make sure it is moving freely.

Other things in the maybe category: brass with thick necks from the factory; brass too long after one firing; cleaning/tumbling/whatever after sizing that makes the neck interior have high friction and resulting high neck tension. Primer pockets all at a weird non-standard depth resulting in primer appearances that don't tell the story as usual.

I suggest one new off the shelf pound of powder, if there is any doubt at all about what you have.
EE2