Loads that maximize barrel life

I am working on my first rifle build. I have the parts together for a 243 Win on a model 12 action. I have another 243 that doesn't see a whole lot of action, but I plan to make this one my "go to" rifle and hope to shoot it a lot with different weight bullets. I've been reloading for 25 years, but never considered that maybe a cooler powder might reduce the temperature of the barrel. I read something on the internet that said that some folks are using very slow powders that burn cooler. Its on the internet, so it has to be true. Have any of you experimented with loads that might extend the life of your barrel?

I know a lot of range shooters are using H 380 for less recoil while keeping the accuracy. Less recoil. Less heat?

Yes, it's called Win 748; which doesn't work in the 243.
Slower powders don't burn cooler, that is all about energy content and burn characteristics. Somewhere I have a chart with energy content and some specific burning temps.... IIRC, sticks are something like 3,500°, whereas most ball powders tended toward 3,300°. But again, that is subject to composition and mix changes. Remember that canister grade powder is a waste dump of the military industrial complex. Hodgdon doesn't call General Dynamics and ask them to make the 1930's patented formula for what you know as H335. They ask for something with a general burning rate and characteristics.
There was an old army research paper done in 37mm weapons with ceramic inserts, attempting to avoid the flame cracking in the throats; read some of it here:
http://www.arl.army.mil/arlreports/2005/ARL-MR-624.pdf

Fast powders will have a cooler gas temp at the muzzle, than the slower burning powders. Somewhere around 1931 there was a book by A.M. Ball who calculated and discussed what you are asking.....

Found you a preview, here:

http://pubs.acs.org/doi/abs/10.1021/ie50257a006

This year is the first year I used the 243 for the matches and P Dogs. All I can tell you is I was amazed at the difference in barrel heat using my finger tips as a gage between different powders I was trying. I think the powder that keeps the barrel cooler after a long string of sighters or 40 rds on dogs in 20-30 minutes should give longer barrel life but I could be wrong.

I could get a laser thermometer and see for myself what the difference in temperature would be, but I might go through several different barrel/ammo combinations before I had an answer.

i never did any actual heat testing but H100v seemed to run a little cooler than H4350 or H4831...and by cooler i mean it seemed to take more rounds for the barrel to heat up from chamber to muzzle...this was in a 28" 6.5mm barrel.

I agree LR. I've shot out one 243 barrel in just 1400rds (due to mag length restrictions on seating depth) and H4350 does seem to heat up much quicker the H100V and accuracy between the to is very close to call. Recoil is snappier with H4350 and more of a push with H100V. This is only about 2,000rds of experience on the 243 though. I think H100V is a pretty good powder in the 243, but have switched to H4350 because of accuracy and velocity consistency dependent on match locations.

I've never tried H100V. I will give it a try, if I can find it.

H100V gets a little squirrely if compressed and its hot outside LOL....it is a good powder and you should be able to find it local to you as theres not a lotta ppl running it.

"Drive it like you stole it!" The "go-to gun" has so many better things to worry about. I know it sounds harsh.....Still think it's true!
When I think powder: I think temp stability? fill ratio? Burn rate vs bullet weight = ACCURACY.........everything else is mute.

My understanding is barrel life can be measured in powder burned so a barrel last let's say 16 pounds of powder worth. That doesn't matter if you push 500 rounds down the pipe or 5000 it is mainly how much powder you burn. I don't remember the amount but maybe sharpshooter remembers and will chime in.

what really takes a toll on barrel life is heat...long strings of fire where the barrel really gets hot...this is why i only shoot a couple of F-class matches a year and the few i do shoot are in the spring or fall never in mid summer when temps are in the 90-100s.

and earl is correct about LBs of powder and barrel life...my first 260 barrel shot 2900 rounds at an average of 40.5g of powder so 2900x40.5 devided by 7000 equals just under 17lbs of powder....now that barrel was still very accurate but i pulled because it was right at the start of a match season so im not sure how many more rounds it would have shot before going south but i think some where between 3-500 which would of meant re-barreling mid match season.

I believe double base powder burns hotter than single base, so stick with single base. Double base contains nitroglycerin in addition to nitrocellulose.