Temperature sensitivity - How much of an issue?

rush709

New member
So it's been mentioned by a couple users here that H380 might not be my best option living in a colder climate. Varget has been suggested as a better option, and I'll pick up a can of it as some point. I'm guessing that there's not an exact formula that will predict performance variations due to temperature changes, but I'm curious about how big the changes are. Again, i'm sure it will vary, but is accuracy effected hugely or just slightly? I could probably live with an inch or so, having shot factory ammo all my life, that'd probably be within that normal variation anyway. Though if things go way off I'll definitely be looking in to the Varget sooner rather than later. Are factory bullets very subject to temperature changes or are more temp stable powders used in those?
 
It all "depends". Some rifle/ammo combos, 100 fps is enough to make a quite noticeable difference in accuracy at point blank range (under 300 yards). Others, that same 100 fps won't even be detectable at the same range. Rifle itself, being a major variable, along with the ammo.

I burned up an awful lot of H380 in .22-250's and .243's in cold weather. Cold, meaning down to about 15F, but mostly in the 20's and 30's. I did see velocity changes of over 100 fps from a warm summer day to a cold winter morning. Can't say it ever made a big enough difference to save a coyotes life though. That was before any powders were being marketed as being less sensitive to temperature. Have since mostly moved on to other powders. One of my favorite .243 coyote loads is still with H380, and a 55 B-tip or 58 Vmax. But, Varget gets about the same 4,000 velocity, with more temperature stability. And the accuracy between the two is a rifle to rifle thing, not anything you can bank on either way.

- DAA
 
Depends on the ammo.

I've used a lot of reloader 15, which is pretty sensitive. Groups CAN go from sub .25 to over .75. It's not really that big of a deal for hunting, but what can be a big deal is shooting a cold weather load in warm or hot weather. In fact, it can be down right dangerous.

These days I use a lot of Benchmark and Varget, and it certainly minimizes the environmental effect.
 
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Rush, have you ever asked yourself how the old timmers put up with temp sensitive powders?

Here is what we did:

1. work up a load in cold weather-designate the load for cold weather hunting loads

2. work up a load in 70*(Spring weather-test in warmer weather).

Common sense is not common until you educate yourself on the subject.

As those before have mentioned, where you get into real trouble is working up a load in cold weather, say 25-35*, then shooting it in 90* temperature.

So, you have two different loads.

Are you organized enough to work up two different loads?

With the availability of components being hit and miss in availability, many will have to learn to adapt to other than Australian powders and if Hillary is elected, there is a good bet that they will not allow the import of those powders and other components into the country, guess where Dupont powders are now made?
 
It's not an issue if you test and collect data in variable conditions. Load notes are pivotal.

Factory loads are just as subject to the same variables as any other. Again, shoot I'm all conditions possible prior to hunting. And record the results...
 
Originally Posted By: CZ527 Groups CAN go from sub .25 to over .75. It's not really that big of a deal for hunting, but what can be a big deal is shooting a cold weather load in warm or hot weather. In fact, it can be down right dangerous.



For hunting purposes, I could live with that. And thanks everyone for the advice on winter vs summer, that's a good point. Warm weather is a good seven months away yet where I'm living, so I'll have a bit of time to do some experimenting. Over the fall / winter I'll work on developing a load my gun likes. So far i've stayed under max load, which is where i'll probably stay for a while yet until a get a bit more experience under the belt. I'm fine with having a little less velocity as long as there's accuracy (and the loads being a little more barrel friendly is a good thing to me too
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I had heard the name Varget a lot in my readings, though only today realized it's a Hodgdon product (I'm pretty new to reloading and was focusing most of my attention on how to safely do the process, hadn't put a whole lot of time into reading about all the different product lines. Had been associating Hodgdon products with numbered naming schemes). My local shop carries Hodgdon products, I'll check if they have any Varget.
 
Originally Posted By: ackleyman
As those before have mentioned, where you get into real trouble is working up a load in cold weather, say 25-35*, then shooting it in 90* temperature.

So, you have two different loads.

Are you organized enough to work up two different loads?



I've never really been one to do a lot of summer shooting. Though with this new reloading hobby, I can see myself getting a range membership and spending a bit of time there (up to this point I mostly only fired shots when hunting, and sighting up rifles in a gravel pit when need be). I'll be sure to start with the lighter loads with H380 come the warmer weather, and I'm sure i'll have picked up some Varget and did some experimenting with it by then too.
 
To me, the PRESSURE changes involved are what keeps me looking at "temp stable " powders. Accuracy change is a secondary consideration, although one to look at. Ackleyman makes a good point about having cold and hot weather loads, and that is certainly doable. I look at it in the sense that if I can get as good of useful accuracy and velocity for my purpose with a given load/gun combo w/ a "temp stable" powder, I see no need to go to a "non-temp stable" powder which costs about the same money. I used H-380 in my old 22-250 which was mostly used in summer, and that's when loads were worked up - worked well enough. Simply picked it initially cuz they said Bruce Hodgdon did so well with it in the 22-250. When I ran out of H-380, I moved on to other powders, and didn't look back as H-380 is known to be less temp stable than many other powders in it's class. - no need to for sentiments sake alone in my case. It appears to me that the development and marketing of "temp stable" powders is something we will see for sometime to come, and may see the "less temp stable" powders fade over time. JMHO.
 
Originally Posted By: rush709..is accuracy effected hugely or just slightly? (by pressure change due to temp changes) ...

Good question !
Given you have done the homework required to locate an accuracy node, the bullet speed changes based on temp should only alter the vertical spread on target.
However the radial spread on target may increase more than just the vertical if the speed moves off of the accuracy node by too much.
So what I'm trying to say is that vertical errors aren't the only errors on target to think about.
We reloaders spend a lot of time and effort chasing accuracy nodes (holy grail) within ladder work-ups, some of us think that's a big part of the fun of reloading.
One thing is for sure, a more temperature stable powder make life easier for those of us that reload/shoot throughout the year.
 
Originally Posted By: Mike BI look at it in the sense that if I can get as good of useful accuracy and velocity for my purpose with a given load/gun combo w/ a "temp stable" powder, I see no need to go to a "non-temp stable" powder which costs about the same money. I used H-380 in my old 22-250 which was mostly used in summer, and that's when loads were worked up - worked well enough. Simply picked it initially cuz they said Bruce Hodgdon did so well with it in the 22-250. When I ran out of H-380, I moved on to other powders, and didn't look back as H-380 is known to be less temp stable than many other powders in it's class. - no need to for sentiments sake alone in my case. It appears to me that the development and marketing of "temp stable" powders is something we will see for sometime to come, and may see the "less temp stable" powders fade over time. JMHO.

I'm in the same boat. Picked the H380 because I was starting reloading with 22-250 and Lyman's book suggests it as a good starting powder for 22-250. I'd rather have year round powder/ammo and not keep separate boxes of ammo for certain temperatures. I'll eventually pick up some varget as I've heard that's not so sensitive and will work well in 22-250 and 308 (my go to calibers). I've still got the better part of a can of H380 (minus 40 cartridges worth), and I plan to get a bit more reloading experience out of it. Adding a can of varget now would just be introducing another variable in, so I'll keep it out of the equation for now. But I will make a point of going out and firing a few shots on a bitter cold day and a more mild day and see how it's effecting things.
 
I shot out my first 22/250 Rem 700 with H380. 38g of H380 with a sierra 1365 is what I shot year round, hot and cold weather. With this particular Remington 700, we got into hitting some coyotes up at some long shots in the winter, and 39.2g is what I loaded for sub45* weather. This 39.2g load shot well at 500 yards, but around 350 was as far as we had to shoot, dessert flood plains where smart yotes would circle, wind us, and not come in.

Couple of ways to test your loads, freeze the loads, pack them in a zip lock bag and put on ice in a cooler. Then the opposite, put the rounds in your arm pit for 5 minutes, or have your shooting partner do the same, remove them from his arm pit one round at a time.

When Extreme powders came out, I shot a lot of 39g of H4350 with a win primer, Sierra 55g 1365 and the same in the BTHP version.

Work up to these loads in your rifle. Remingtons are 14T, faster twists jack up the pressure, so be careful.
 
When I started loading the .22-250 I tried H380. Started in May for groundhog hunting, and everything shot great. Worked all summer. In Sept as temps started to drop I noticed the POI changed by about 1". Adjusted the scope and shot the rifle through Sept with no ill effects. Oct came and again the POI changed by about 1". This time I switched to Varget. That was 5 years ago and all is well.

I'm sure the POI still changes but not as much as it did with H380. I live in OH where winters are cold and summers can be hot. I'll stay with Varget as it works for me.

Soon as I get the chance I want to try IMR 8208 as it gives more velocity then Varget.
 
Originally Posted By: joedWhen I started loading the .22-250 I tried H380. Started in May for groundhog hunting, and everything shot great. Worked all summer. In Sept as temps started to drop I noticed the POI changed by about 1". Adjusted the scope and shot the rifle through Sept with no ill effects. Oct came and again the POI changed by about 1". This time I switched to Varget. That was 5 years ago and all is well.

I'm sure the POI still changes but not as much as it did with H380. I live in OH where winters are cold and summers can be hot. I'll stay with Varget as it works for me.

Soon as I get the chance I want to try IMR 8208 as it gives more velocity then Varget.

That 1", how far were you shooting?

I'll be picking up varget as my next powder I think. Though I've got a good bit of the H380 left, so I'll make use of that as well.
 
this is the work i did many years ago with my rem 788 in 22-250 with H 380 started in july 70 degrees 40 gr nosler bts 10 shot avg.3894fps next try 40 degrees same load 3748 fps next 25 degrees 3527 fps next 15 degrees 3464 fps next 0 degrees 3341 fps and lastly -20 degrees 3204 fps.these were all 10 shot test averaged by chrony these were with cci primers and winchester brass.I also have results for .243 and .223 with several different powers as well as several powers with this 22-250 bill
 
Originally Posted By: 19grizz69this is the work i did many years ago with my rem 788 in 22-250 with H 380 started in july 70 degrees 40 gr nosler bts 10 shot avg.3894fps next try 40 degrees same load 3748 fps next 25 degrees 3527 fps next 15 degrees 3464 fps next 0 degrees 3341 fps and lastly -20 degrees 3204 fps.these were all 10 shot test averaged by chrony these were with cci primers and winchester brass.I also have results for .243 and .223 with several different powers as well as several powers with this 22-250 bill

Wow, that's a pretty dramatic change. I wouldnt have thought it would have been that big a difference, but the numbers dont lie. Thanks for that info.
 
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