How to you deal with powder temperature sensitivity and velocity change with temperature change?

Ballistics program that you can update like the one on Gunwerks or Horus vision.

But I think you are talking about the effects on certain powders on heat.

I don't, I use Hogden Extreme powders where I can. We had 15 degree temps in January and will have 115 degree temps within a month.

Most loads shoot best if they aren't the hottest loads.

As the most consistent load among extreme deviation for feet per second is generally a mid-range load.

quote:

Originally posted by Big Wonderful Wyoming:
Ballistics program that you can update like the one on Gunwerks or Horus vision.

But I think you are talking about the effects on certain powders on heat.

I don't, I use Hogden Extreme powders where I can. We had 15 degree temps in January and will have 115 degree temps within a month.

Most loads shoot best if they aren't the hottest loads.

As the most consistent load among extreme deviation for feet per second is generally a mid-range load.

I tested some Extreme powders once when it was -30 F vs cartridges heated via my truck heater (they were quite warm to the touch). I was really impressed with the lack of temp sensitivity of Extreme and astounded by the difference I saw with spherical powders - they had about a 150 fps difference IIRC.

quote:

Originally posted by Ackley Improved User:
How to you deal with powder temperature sensitivity and velocity change with temperature change?

What I've found for temperature sensitivity at -40 C (or F; same thing)is all the powders suck. Its best handled by staying home. At -20 C (-4 F) sanity mostly returns.

For a quick and dirty, if not technically perfect fix I'll just get on at 650 at my range and slip the scale. That make all the velocity, heavy air, possible zero shift, and even small click error lies align at that distance; and a goodly margin on each side. At close range who cares? At much longer range it wouldn't be the first time someone took a sighter. In a general sort of way a 1 MOA scale slip will put me in winter mode on my longer range rifles. I've done a limited amount of summer and winter load for the same rifle shooting, though much of it wasn't exactly planned. Some loads developed in the winter got a little too warm in the summer. Switching back and forth does cut down on the summer/winter error.



More general purpose, zero to 5-600 yard hunting rifles I'll just pick a 4 or 500 yard crosshair and re-sight the rifle. If that means that instead of shooting 5 inches low at 500 it now shoots a couple inches higher at 200 than before,(for example) who cares?

I guess what I'm doing is twisting two curves for a best fit, not unlike tweaking a a sight-in to match a subtention reticle.

I keep my loaded rounds in a cooler out shooting; and I load about ten seconds before I fire.

The major culprit is "cooking" in a warm to hot barrel for varying amounts of time.

I have been shooting 1000yrd matches for some years, sure, we try to strive to have consistent dopes, but, who doesn't check their dope and adjust when the match starts?

I never really consider temp sensitivity, if it shoots consistently, groups well and holds it's MoA, I use it.

I single load, and my ammo is always in a MTM case with a moist towel over it.

I find lot to lot variation to also effect my dopes and sweet spot. I am always adjusting powder charge to keep the node as the throat erodes anyway.

Cheers.

Powder temperature sensitivity is most important to those of us who want first shot hits, especially when hunting.

I just shot a Palma match today and it was sunny and 95 degrees here at noon. My ammunition stayed in the shade on the line and didn't get dropped in the action until I was ready to load and shoot it.

I used my new "Barrel Cool" fan between strings and my gun barrel was noticeably cooler than the other guy's guns on my relay.

At one time Varget was considered to have the least variance due to temperature changes, but there may well be even better powders now?? Have been told that as a rule a 15 deg. increase in temperature can result in as much as 1moa change in bullet impact at the longer ranges. Say at 9am upon match start, temperature at 65 degrees and by 12 noon temperature is now up to 95 deg. you are looking at some 2 moa of change. Is that true, can't say it is exactly correct but have seen considerable change due to temperature at 1000yd matches, Palma, etc.

Too much emphasis is placed on temp sensitivity.
Atmospheric conditions play havoc with dope as the day progresses also, a lot of these temp swings people blame on the powder are simply air density changes. Warmer air is less dense, therefore your MoA will change as the day warms up, or cools down, as the case may be.

BC also changes as the air thins or thickens, it's the nature of the beast we play with, unfortunately.

Cheers.

I only have a couple of rules I made for myself...never use ball powder for anything other than making noise and for just about every rifle I own based on the /06 case or belted cases good old H-4350 is used...bad experience bench rest match shooting with ball powders caused rule one 1, about went crazy with temperature poi changes..never again! I've used that powder from -20 F to 95 F and have never noticed any real poi differences, I'll sacrifice a 100 fps using it in my mags for repeatability and accuracy any day...great powder..

quote:

Originally posted by frankinthelaurels:
I only have a couple of rules I made for myself...never use ball powder for anything other than making noise and for just about every rifle I own based on the /06 case or belted cases good old H-4350 is used...bad experience bench rest match shooting with ball powders caused rule one 1, about went crazy with temperature poi changes..never again! I've used that powder from -20 F to 95 F and have never noticed any real poi differences, I'll sacrifice a 100 fps using it in my mags for repeatability and accuracy any day...great powder..

H4350 or AR2209 is a very stable powder. Shame I cant run the big capacity magnums on it. I gave up on ball powders 20 years ago. They are by far the most temperature sensitive powder I have used.

quote:

Originally posted by Ackley Improved User:
How to you deal with powder temperature sensitivity and velocity change with temperature change?

I shoot the load year round at 300-600 yards,noting POI in various temps(in my region this can run from roughly 0-10 degrees up to 90F or so. But most shooting is between those extremes.

If I don't see significant changes over a long string of range sessions, I don't worry about it.

quote:

Originally posted by Bwana_500:

quote:

Originally posted by frankinthelaurels:
I only have a couple of rules I made for myself...never use ball powder for anything other than making noise and for just about every rifle I own based on the /06 case or belted cases good old H-4350 is used...bad experience bench rest match shooting with ball powders caused rule one 1, about went crazy with temperature poi changes..never again! I've used that powder from -20 F to 95 F and have never noticed any real poi differences, I'll sacrifice a 100 fps using it in my mags for repeatability and accuracy any day...great powder..

H4350 or AR2209 is a very stable powder. Shame I cant run the big capacity magnums on it. I gave up on ball powders 20 years ago. They are by far the most temperature sensitive powder I have used.

Bwana_500
I thought all the AR range of powders which are just re-branded for Hodgdon, were temperature insensitive?
AR2213 (H4831) and AR2217 (H1000) and even a couple of slower ones again are the magnum powders?

quote:

Originally posted by eagle27:

quote:

Originally posted by Bwana_500:

quote:

Originally posted by frankinthelaurels:
I only have a couple of rules I made for myself...never use ball powder for anything other than making noise and for just about every rifle I own based on the /06 case or belted cases good old H-4350 is used...bad experience bench rest match shooting with ball powders caused rule one 1, about went crazy with temperature poi changes..never again! I've used that powder from -20 F to 95 F and have never noticed any real poi differences, I'll sacrifice a 100 fps using it in my mags for repeatability and accuracy any day...great powder..

H4350 or AR2209 is a very stable powder. Shame I cant run the big capacity magnums on it. I gave up on ball powders 20 years ago. They are by far the most temperature sensitive powder I have used.

Bwana_500
I thought all the AR range of powders which are just re-branded for Hodgdon, were temperature insensitive?
AR2213 (H4831) and AR2217 (H1000) and even a couple of slower ones again are the magnum powders?

Yep, that's right, and to continue:

ADI's AR2225 = Retumbo "Extreme"
and
ADI's AR2218 = H50BMG "Extreme"

Extremely thermoballistically independent (TBI).

Thank the Aussies for some great powders.

On some of my old chronograph data with the .375 Wby I noted 1/2 fps per degree F of thermoballistic dependence (TBD) with H4350.
IMR 4350 gave 4 times higher TBD at about 2 fps per degree F.

TBI is good. TBI is a qualitative adjective.
TBD is a quantitative measure.
Higher TBD is worse.

For you metric people:
H4350: 0.27 meters/sec per degree C of TBD
IMR 4350: 1.10 meters/sec per degree C of TBD


Rifles In Progress by
Riflecrank Internationale Permanente aka Squirrel Killer
Pet Wildcat Certifying Authority and Tree Rat Control Specialist
NRA Life Benefactor and Beneficiary to the Fourth Degree
https://home.nra.org/