Tempreture Sensitive Powders

S

SEHunter

New member
Is there any publication or write up on the PN site that discusses or lists the range of powders in order or a catgory of how temp stable or unstable they are?

If not and you know, would you mind shareing?

For the benefit of others, any powders would be great. I personally use Varget, H380, IMR4895, IMR4064, IMR3031, IMR4350, H414, H4831, IMR4831, IMR7828, RL22, Norma MRP, Possibly superformance and 8028 soon. Thanks for any help.
 
Rifle powders have become very complex beasts in the last several decades. In simpler times you could count on the single based propellants being a little less temperature sensitive. With the maturation of deterrent coating and more complex propellant chemistry in general; it just is not that simple.

As a general rule the Extreme series from Hodgdon is pretty insensitive to some broad swings in temperature. Along those same lines the Vihtavuori Oy 100 series and the Norma 200 series are also fairly stable. Even the VV 500 series is a good bit more stable than it was, just a decade ago (though it is still sensitive). At one time, all ball powders were quite temperature sensitive. Western Powders has really set the new standard in this regard. Many of their powders for rifle applications are quite consistent. Alliant has also made great strides with their R series (Though R-17 is still sensitive).

One other thing, and I have witnessed this first hand with both transducers and strain gauges. The same powder operating at the same nominal pressures will respond differently to a change in temperature in different cartridges. And then there are primers.................
John
 
Ok. I had never heard of any list or chart, i was just curious. I know the Hodgden "Extreme" series is supposed to be stable. As mentioned, i have heard ball powder, such as H380, is very sensitive but i didnt know if that was an accurate generalization across the board or not.

I do all my load developement in 30'F to 60'F because i hate sweating all over my guns. In the summer, i would be hunting in the evenings where it may be anywhere between the upper 70s and low to mid 80s.

So basically, i wondered if the H380 in my 22-250 loads that shoot awesome on these cool winter mid-mornings will shoot terrible when i squeeze the trigger on a coyote on a muggy August evening here in Ga.
 
Maybe someone will invent the "cartridge snuggie" that will keep our rounds warm in the winter then in summer, no worries.
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Seriously though, if anyone has a good article or write up on the subject, that would be great.
 
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Through the 70's and 80's, I shot H380 in a 22/250 from 38.0g to 39.2g(hot) in some guns. In cold weather I used the 39.2g with a 55g Sierra, and in 85*temps+, I used 38.0g with the 55's. We shot hundreds of coyotes in Mexico, Az, Ca, and Nv.

When I went to a 6 Rem and 243 shooting the 60g Sierra with a max load of 760, I shot the same load year round. Then I switched to the 80g Single shot pistol bullet in the 243 and 6 rem, and shot an over max book load of IMR 4064 with a Fed 210 all year long.

Shooting p. dogs with a 223, I shot a load of 26.5g of Win 748 with a 55g bullet, then shot 27.5g with a 50, never any problems in 14" twists. I shot Win 760 in my 22/250 AI and 243 AI (12" twists in both) on dog towns, temps got to 95* but we did shoot in the shade.

With all the ball powder that I have shot over the years, 748, Ball C2, H335, 760, 2230-S, 2230, 2520 I have NEVER had a problem in the field. Then again, I don't live or hunt in extreme cold conditions. I lived in Ca. for 20 years and Az for 8 years, shot just about everything that walked, flew, and crawled.

If you live in a area where you are working up loads in the Winter where temps are minus 32* then hunt in temps in 85* temps, you have a special challenge...temp sensitive powders become a special issue for you.

Unfortunately, I have not got Varget to shoot tiny groups in my 22/250 or 243's with various bullets, everything else shoots better, about 1" is the best that I can come up with loading with Varget. I do get much better accuracy with IMR 4064.

I think that there is a lot of confusion about "temp sensitive". Some shooters only buy one can small can of powder at a time, their new powder is a hotter or slower lot and they call the powder temp sensitive....HERE'S YOUR SIGN!!!

Some shooters let their ammo sit out in the sun, as you see in the pics of shooters sitting on a p. dog town and they are the first in line to call certain powders temp sensitive....IDIOT!!! Others let their ammo cook in a hot barrel while they are looking for their next target(creature), hot barrel causes pressures to spike...must be a temp sensitive powder...IDIOT!

If your rifle is extremely accurate on the ragged edge of stiff bolt lift, case head scuffing, and flat primers, don't blame the powder when the temps go up 20* and you get beat your bolt open with a 2x4, a shooter is an idiot that loads in this mannor.

Working up your loads on the ragged edge of max pressures when it is 35* and expecting those loads not to be HOT when it turns 85* is a fool's folly...no matter what the powder...don't be an IDIOT! If you work up your loads in 75* temps, chances are you are ok when it turns 95* or 35* as long as you don't load on the ragged edge of hot pressure.

I was coached by an old benchrest shooter when I was in my teens shooting benchrest that no matter what rifle you are shooting, always know what is high pressure for that particular rifle because no rifle can read a reloading manual. Also, most rifles will shoot their most accurate within 2.0g of what is a max load for that particular rifle.

So I load one round and one round only increasing the powder charge by .5g until I see pressure signs. Once I know what the max load@ pressure is for that particular powder/bullet combo, I can start to make some logical conclusions for temps that I will be shooting in. If I don't know what is the max load, I am taking a HUGE chance.

One thing that I have found is that the deterrent coatings on the LESS TEMP SENSITIVE powders need a hotter primer, they must be harder to ignite.......hummmmmmmmmmmm........

The uneducated say that I always stay away from book max loads or I always stay in the middle of the Minimum to Max load...the uneducated reloading novice does these things(you can reload for 30 years doing the same wrong thing and still be a novice).

Educate yourselves on proper advanced reloading techniques. If you read 4 different reloading manuals, you will see 4 different Max loads for your given situation. The book lists for "Reference Only" what they found to be a max load for the barrel and lot# of powder they were using. Also, there is a fudge factor based on folks that let their ammo sit in the sun at 125* and those brave souls that hunt in MINUS 25* where pressures spike.

So, you need to determine what is the max load for your barrel with the lot# of powder that you are using. If you change lot#, you start over...sorry!

Good luck on your education of temp sensitive this and that.

 
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Ackleyman, thanks. That makes perfect sence. Maybe reloading manuals should have a disclaimer in them with these facts. I will be the first to admit that lazyness is the reason to hope to find the perfect answer to questions like mine so that i dont have to spend the extra time and money to find out what my gun in my climate will do.
 
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