Temperature stable powders
- Thread starter Wis65x55
- Start date
Depends on how far you need to setup to be accurate. IMO ES's of a load need to under 2% of velocity at 500 yds and under 1% to go to 1000yds and stay moa.
So if load is 3,000 fps es's under 60fps will take you to near 500 and es's under 30 will take you to near 1000yds. For 1000yd setups I use .7% of average velocity.
Now take that into consideration as to how much velocity change per degree of temp change. Some powders are as much 3fps per grain depending on use application matching case fill and bullet weights.
Most of your "stable" powders are still going to change velocity in the .25 to .5 fps per degree range. This can make a "stable" load stay within the same es's as mentioned above at 1% of average velocity over about 75 - 80 degree temp changes. That is about as stable as you are really going to get with most loads.
There is NO such thing as a truly temperature powder, the new ones are much better than most of those of old. Now you may build a specific load with the newer powders that claim temp stability but it will be on a load to load basis, not just pick a temp stable powder and it be "stable". Too many variables::::::
Bullet weights
Overbore
Case Fill
Burn rate changes due to case geometry
etc.
So if load is 3,000 fps es's under 60fps will take you to near 500 and es's under 30 will take you to near 1000yds. For 1000yd setups I use .7% of average velocity.
Now take that into consideration as to how much velocity change per degree of temp change. Some powders are as much 3fps per grain depending on use application matching case fill and bullet weights.
Most of your "stable" powders are still going to change velocity in the .25 to .5 fps per degree range. This can make a "stable" load stay within the same es's as mentioned above at 1% of average velocity over about 75 - 80 degree temp changes. That is about as stable as you are really going to get with most loads.
There is NO such thing as a truly temperature powder, the new ones are much better than most of those of old. Now you may build a specific load with the newer powders that claim temp stability but it will be on a load to load basis, not just pick a temp stable powder and it be "stable". Too many variables::::::
Bullet weights
Overbore
Case Fill
Burn rate changes due to case geometry
etc.
Here is a really good comparison to what many consider the most temperature stable powder made, H4350. Note the velocity changes on H4350 also. This is considered stable by most long range shooters. The key is KNOW what your changes are with temp and adjust accordingly.
http://bulletin.accurateshooter.com/201 ... -imr-4451/
http://bulletin.accurateshooter.com/201 ... -imr-4451/
joelkdouglas
Handloader
- Jun 5, 2011
- 1,310
- 3
Keith, if you will hunt in temperatures that you have difficulty preparing loads for where you live, it's more important to use a temp resistant powder.
If you can develop a load in the same general temperature and altitude range that you hunt I don't think it's very important to use temp resistant powders.
Conversely, if you load max charges at 20 degrees and then shoot them in the summertime you could run into pressure problems. Temp resistant powders reduce this difference, but as MAinAR noted they don't eliminate them completely.
If you can develop a load in the same general temperature and altitude range that you hunt I don't think it's very important to use temp resistant powders.
Conversely, if you load max charges at 20 degrees and then shoot them in the summertime you could run into pressure problems. Temp resistant powders reduce this difference, but as MAinAR noted they don't eliminate them completely.
Wyo7200
Handloader
- Aug 20, 2014
- 565
- 1
I'll post a list of powder fps changes you can probably expect tomorrow when I get to work. Its a good comparison.
How important is reloading with temp stable powder though? I have a hard time answering that since a lot old powders are not anywhere close to being as resistant as today's powders are. The old powders are still being produced (many under different names) and still being bought... Temp stable or not, the reloader will work it out in one way or another.
How important is reloading with temp stable powder though? I have a hard time answering that since a lot old powders are not anywhere close to being as resistant as today's powders are. The old powders are still being produced (many under different names) and still being bought... Temp stable or not, the reloader will work it out in one way or another.
I've started paying more attention to more temperature stable Powders. When I ran out of 22 and 25, I've switched to 23 and 26. I use a bit of Hodgdons powders and just picked up some H322 for the 200 ABs in the Whelen. I've never had a problem with them but I'd rather be safe than sorry.
Wyo7200
Handloader
- Aug 20, 2014
- 565
- 1
Results may vary.
DrMike
Ballistician
- Nov 8, 2006
- 37,312
- 5,976
I have to say that I've never been exceptionally fussy about the temperature stable powders. I keep quite a few on hand because I have so many requests to develop loads with them. In fairness, I don't hunt in hot temperatures. Mid-August temperatures here in BC will range from freezing to ~70. At the ranges I will shoot, the effect on velocity/trajectory is minimal. If I was planning on a hunt in the Sonoran Desert or in Africa, perhaps I would be more concerned. As it is, my hunting is during a period of Mid-August to Mid-June and the temperatures are not exceptionally high (though they can drop quite low).
- Thread starter
- #12
wildgene
Handloader
- Jul 4, 2011
- 1,597
- 2
Wis65x55":1hmfg7rp said:
...depends...
...lots of factors involved including B.C. & Altitude Density, etc., but let's stick w/ temp. stability. Everyone wants things to be as consistent as possible, but some powders are more temp sensitive than others, change the Time of Flight & everything changes w/ it. That said, using a powder, say RL-22, that's fairly notorious for sensitivity w/ a decent bullet, a loss of 100fps. will give you around 3-4" more drop @ 500yds., closer to 2' @ 1000yds...
...say you check your 'zero' @ as close to the temp. you'll be hunting as possible, & you probably won't be shooting over 600yds., your change in POI won't be that significant. Now if you built your load @ 40*, & you're shooting a 1000yd. Palma Match & it's 90* on the firing line, your ammo is heating to 120* in the direct sun, you're probably going to encounter some real problems...
