Stable Powder

[krobins]

I have a month off for Christmas and the ranchs i work on are thinking that they want need me so i have to kill a lot of time. So this looks like were i am going to be building my hunting loads for a my rifles.

Were i live it is very cold during this time of year warm days may hit 32F. I need a good stable powder(s) to work up my loads for two rifles.

Savage 11f 223
Savage 116 300wm

Im not lookin for powders that will make it possible to drive tiny little groups, though it would be nice. What i am looking for is a powder(s) that will not be change to much from this Dec cold to when i go hunting during the spring and fall, when it can get up to 100F.

I will be shooting 55g bullets out of the 223 and Nosler Partions and Accubounds out of the 300wm probably of the 180g class.

Anything is apprciated.

[MT4XFore]

robins: Hogdon makes a line of powders called "Extreme" powders, they are made to be very tolerant of temperature changes. Ramshot powders are also not affected by temperature change. Either of these lines of powders would work nicely for you. Good luck,
Jim

[krobins]

I am looking at not spending a fortune, however before i put my foot in my mouth i have not checked prices on these. I use now imr 4831 and w748. How stable are these.

Additionally is this somethin that i should worry to much about how much will the temp change effect the accuracy.

Thanks

[bailey1474]

I'm not sure about the IMR but the Win is very temp sensitive. Accuracy is not directly effected but velocity on pressure are and these will in turn effect the accuracy.

[goodgrouper]

Sorry to say this but want you want does not exist.
Since velocity is a direct result of pressure, any magical coating or process of manufacturing that would reduce pressure on a 90 degree day would also reduce pressure on a freezing day thus giving you velocity reductions from faster to slower. In essence, how can a powder change it's burn rate or desired pressure(all by itself) while inside the bottle while maintaining a specific wanted velocity when the temp has now dropped 58 degrees?

Getting back to velo being a result of pressure, there are many many things that influence pressure. To name two that are relevant here are ambient air temps, and ambient temperature of the steel used in the action and barrel. As the temperature of your steel climbs from sunlight, air temp, or residual heat from previous shooting, the ability of it to increase pressure also increases. <font color="blue"> No powder available to citizens of this country can change this simple fact. </font>

Ever notice while chronographing that if you let a cartridge sit in a chamber (that has already been heated up from previous shooting) for several minutes that normally shoots standard deviations in the single digits, that it will spike up in velocity? THis is a direct result of higher temperature barrel steel causing internal pressures to rise. If your barrel goes from stone cold freezing to too hot to touch, it may have had the outside temperature raise 100 degrees or more. So when the ambient air temp changes your barrel steel temp from 32 to 90, it also changes the internal pressure proportionately which in turn increases your velocity!

All the magical coatings and fairy dust in the world cannot do a thing to change this to a degree that would make enough difference to us.

Only in the world of marketing and advertising developers does this basic principle of internal ballistics not exist.

Or in other words: WHen using Hodgdon, IMR, VV, Win, Ramshot, ALliant, Accurate, or any of the others, <font color="red"> you must find a suitable load and alter it slightly with the changing seasons. </font>
Some change more, some change less based on their composition and exposed surface area, but the bottom line is that they ALL change.

Sorry to be the bearer of bad news, but this might save you from spending money on miracle gimmicks and chasing your tail. [img]/ubbthreads/images/graemlins/frown.gif[/img]

[royinidaho]

GG,

Is the pressure/velocity change due to chamber/bbl temp. or the increased powder temp. due to time spent in the chamber of a hot chamber/bbl?

I 'think' I know the answer, but since hanging out around here, what seems obvious to me has been way wrong. This may be one of those things.

BTW, w/RL-22 from summer to winter with the same load I loose ~130 FPS. Ouch! Also a bit skeer'd to have a winter and summer load laying around. Some times I space things.[img]/ubbthreads/images/graemlins/crazy.gif[/img]

Tnx

[goodgrouper]

Internal pressures rise from both the steel being warmer and the powder/brass/primer being warmer. Remember what happens to ammo left in a ammo box in the sun? Why does it shoot faster and have more pressure?

The same thing happens to ammo that is heated up in a chamber. In full automatic rifles under sustained fire, a round can actually cook off (fire without the trigger being pulled) from internal chamber heat.

So basicly, it doesn't matter how the round got heated, it will have the same effect on pressure and there ain't a dang thing the powder can do about it. [img]/ubbthreads/images/graemlins/frown.gif[/img]


My 300 winnie likes RL-22 also and there is 100-175 fps difference between my summer load and my winter load depending on the lot! Crazy. That is why I never load huge quantities of ammo at one time unless I am positive what time of the year I'm going to be shooting them in.

Generally, I will go one grain low and one grain high of the normal load and chrono the stuff a few days before the hunt or shooting session just to stay on top of things. Pain in the rear I know but that is what you have to do to stay on the cutting edge of performance.