An interesting article on temperaure sensitive vs not as sensitive powder

[terminator]

http://www.rifleshootermag.com/accuracy-tests/fact-fiction-gunpowder-temperature-sensitivity/

[dubyam]

That's a good article, Rodger. I've often wondered if the velocities for my ammo with IMR7828ssc were sufficiently different at freezing temps to cause a miss. Never really felt like I was losing anything from 60-80deg load development temps to 20-40deg hunting temps. This confirms it for me.

[Blackbear3]

Thanks for sharing Roger, interesting article.

[rockville]

Yes it's a real good article. Really ties into some of the questions I have had lately about which powder to try out.

[danno50]

Really interesting article Roger. I've heard a lot of the guys on here talk about temperature sensitive powders and possible effects of their point of impact shift,(along with velocity) and this test helped to explain how its possible under these test conditions.

[danno50]

Quote from Hornady website:
Superformance ammunition is 100 to 200 fps FASTER than any conventional ammunition on the market today, and achieves this performance in EVERY gun, WITHOUT increases in felt recoil, muzzle blast, temperature sensitivity, fouling or loss of accuracy.Increases in rifle performance, no increases in barrel wear and felt recoil, along with superior temperature stability are all realized with Superformance ammunition.

Because of the the R&D of say Hornady and Weatherby ammunition, are they less susceptible to changes in velocity and POI in those test conditions, or is all factory ammunition less susceptible, than say handloaders ammo? I used Hornady and Weatherby as examples because no one knows what powders or mix of powders these mfg's use to achieve their results.

[southtxkiller]

I use hornady superformance in 270 win and 243 win,i haven't tested the 243 but I did chrono the 270win in 130 sst at 3190 from a 24 inch barrel vanguard about 75 degrees,its advertised on the box at 3200 fps,i was bored one day and decided to pull the bullet out of one to measure the powder charge to see how close it was to h4831 load data,ended up weighing 61 grains,anyway the powder was very interesting looking,it was a flake type powder rather than the extruded powder you typical see in rifle powder and the flakes were very shiny almost as if they were chrome plated,I don't know what any of that means but they do achieve the velocity that they advertise,not much temperature extreme to experiment with in texas,I also have been using reloader 22 in 7mm wby and 257 wby for over 20 years and never experienced issues with temperature sensitivity shooting out to 300 yards,I do my load development in the spring and fall I try not to shoot when its much above 75 degrees outside and I rarely get a chance to hunt in temperatures below 30 degrees.

[dubyam]

My guess with Hornady's Superformance (and with their Light Magnum and Heavy Magnum before it) is that these rounds are loaded with a slimmer margin against SAAMI specs, or by mildly exceeding those specs. Sure, they do like every manufacturer does and load using powders we handkoaders can't get. But there is no free lunch, and no breaking the laws of physics, even for Scotty from Star Trek. I came to this conclusion because Browning was very careful to explain in print and live in person that the use of Light Magnum loads was a warranty voiding activity for BAR owners. Now, in speaking with a Browning engineer at length about this issue, I was told the pressure wave was too strong and would batter the mechanism, causing it to eventually fail. When I discussed handloading, that same engineer advised me to use mid-burn-rate powders which were not progressive, for most reliable cycling, but assured me the BAR would cycle safe loads using any suitable powder for the 243Win and 100gr bullet in which I expressed interest. So using slow powders, including the various progressives like IMR7828ssc, is acceptable, but using Hornady's Light Mag or Superformance ammo is not. That tells me, along with the "pressure wave" comment from the engineer, that the way Hornady is making velocity is exactly how it's always made - with corresponding pressure.

I'll also go ahead and call BS on their claim that their ammo, using the same bullet weight, at a higher velocity, has no increase in felt recoil. Again, Newton's Laws of Motion, especially the 3rd one, apply here, as they do everywhere on earth. Same mass, greater velocity, greater resistance to that velocity (in the form of recoil). No way around it, except in the rarities air of the marketing department.

As for the powder question you ask, Danno, I can only say that I've seen factory ammo vary pretty widely in velocity over my chronograph comparing hot and cold velocities. At least as much as handloads, in most cases. I can't speak for all factory ammo, but the various brands I've tried (a dozen or so) have all behaved pretty similarly, reading through my range notes.

[7mmweatherby]

Temperature extreme be more important to match shooters as most hunting situations much closer than long range match shooting as most factory hunting rifles not made with tight tolerance to shoot them distance anyways as I was saying most factory rifles there always exception to the fact lol

I believe be more important stay with your most accurate powder for your hunting rifle then change to the extreme that may not be as accurate unless extreme powder is your most accurate win win         

Just couple weeks ago changed bullet brand (same weight ) and changed powders did not change point of impact @100yds(h222 to varget ) (hornady to nosler) just goes to show you @ 100 yds you not notice fps difference as you will down range start getting vertical stringing

[PARA45]

Interesting article.  Thanks for sharing Roger!

[7mmweatherby]

Duby , possibly with a powder blend that burns from chamber to end of barrel pushing projectile entire way out instead of instant burn at chamber could increase fps without increasing recoil because of longer burn rate not sure if that's what's going on only thing makes since to me I can't believe Hornady market product without some type data back it up

I courous see how they doing that also I know on my bench pack more powder increase recoil but I don't have all the technical resources Hornady has

[dubyam]

Even with a progressive burn blend - which while possible may be neither practical or consistent - I think you'd just trade ignited powder for propelled powder, which would add to recoil accordingly. Even with current calculations, similar velocities with different powder charges offer differing recoil, so propelled powder definitely adds to recoil.

I'm sure Hornady has marketers skilled in the methods of saying things which are approximately true and yet are misleading in how they are phrased.

[eford]

I have found RL-22 to have from lot to lot differences that show up at point of impact. I have not tested it lately on a Magnetospeed chronograph to find how much (if any) those differences are. I might not have two different lots of the powder anyway. I have not seen these differences with RL-19 or RL-17.

Varget, H-4350, H-4831, H-1000 have been almost identical in hot and cold weather with their respective point of impact. That shouldn't surprise anyone. H-4350 has shown the narrowest differences with cold and hot temperatures. No wonder the target shooters are buying so much of it and it is so hard to find.

Over the counter (canister) Superformance is almost the same burning speed as RL-19 and H-4831. SF has never been touted as temperature resistant. The cool weather differences with SFs point of impact were shown to me when trying to hit steel at 1,000 yards. Below 40 degrees it was a different acting load than at around 65-70 degrees. Barrel heat is a factor in that as well but I have rarely shot fast enough to make a barrel hot to the touch.  Inside of 600 yards when shooting steel the SF loads have been fine in cooler temps. I think the variances become easier to see with the longer shots.

The author of the story had a glaring incorrect statement in a story a few years ago about the effects of weather and geography on the flight of a bullet. Anything with his name on it is something I have to take with a grain of salt.

[badsection]

After reading reviews of the "super powders" in several calibers, over pressure signs are fairly common. Getting around basic loading principles is damn near impossible.  I'm not a max load type of person to start with. I find what shoots best and quit there. Temperature swings here MIGHT be 40 degrees in any case. Did we discuss this article before? It is 3 years old. 

[zonie]

I have no doubt  more extreme outside temperature spreads or other induced factors such as leaving your ammo on the dash of your truck in the middle of an Arizona desert summer day can and does have an affect on ammo.  In my case using loads in my son's 270 win  while initial load work-up was done in the much cooler winter months in the Arizona mtns, and then taking the same loads down in the desert when it was bouncing 115 in the shade while shooting .  Yes I did stick the bolt .  I backed off the loads by 2 grains and problem solved.    That particular rifle a Rem 721 can not be loaded to the same maximum loadings as compared to our other Ruger 77 or  pre-64 Winchester model 70 all in 270 Winchester.  In an of itself is to be expected not all rifles are capable of the exact same pressures as other rifles and this is not to say all Rem series 721 or 700's will do the same thing as ours did.  I am an absolute firm believer handloading and testing  at maximum should be done in the hottest summer months because of this reason.  Everything in our handloadings of all three 270 rifles  was done with the same recipe  i.e. same brass, same, primers, same bullets, same powder, same coal , etc.  The only difference was the rifle.  If you change one thing it can make a difference in pressures and that might be a bad thing especially working at top ends.  Test  with a specific gun when it's hot out and you lessen the likely hood of overheating the powders hence causing over pressures.