Specific Heat Content of SR 4759

[Bill*B]

Hello, all. Does anyone know the specific heat content of 4759 powder? I have been unable to find this. Regards, Bill.

[ascast]

I am curious, why do you want that info?

[Bill*B]

I am interested in a reduced "target load", to optimize barrel life. Granted, while most reduced loads will outlast me, it's nice to know which powders are most appropriate. SR 4759 has bulk - a real positive - but if it burns "hot" then I might choose other candidates. Bill

[ascast]

Well, I did not know that one would lead to the other. I do know 4759 is no longer made. I real used a bunch of it.

[M-Tecs]

I am interested in a reduced "target load", to optimize barrel life. Granted, while most reduced loads will outlast me, it's nice to know which powders are most appropriate. SR 4759 has bulk - a real positive - but if it burns "hot" then I might choose other candidates. Bill

With reduced loads and cast you should be able to surpass the 50K mark. How much SR 4759 do you currently have?

[M-Tecs]

Well, I did not know that one would lead to the other. I do know 4759 is no longer made. I real used a bunch of it.

The high energy powders tend to be the hardest on throats.

https://forum.accurateshooter.com/th...range.3878902/

https://www.rugerforum.net/threads/w...olvers.124332/

[Green Frog]

When I got started in Schuetzen I gravitated toward IMR 4759 because it was reputed to be “gentle” on old soft steel barrels like my century old 32-40 high wall Winchester. I settled on 13.6 grains of 4759 behind a breech seated or a fixed bullet of 185-200 gr. I shot a fair amount of it and never saw any undue throat erosion nor barrel wear. I’m glad I still have 8-10 pounds of it but now I have to conserve it for that and similar applications… “they ain’t makin’ no more of it!”

BTW and FWIW, I used to joke about how dirty it shot… turns out at lower pressures it doesn’t burn as clean. I used to say if it wasn’t leaving a dirty bore you weren’t doing it right. What I should have said was a dirty bore means you’ve got a good mild load. To respond directly to your stated question, I can’t give you the specific heat information you request, but based on my personal experience and observations, I would expect it to do just what you want if you stick to low end loadings. What rifle and what cartridge are you thinking of using, and do you have access to a supply of 4759 (or the point becomes moot)?

Froggie

[Bill*B]

Thanks, all! I have several pounds of 4759, so based on your experiences, I might as well use it. I was thinking of the .220 Swift (don't laugh, please). Speer actually published - and the loads are still online - .220 Swift loads using 4759. With a 55 grain bullet, they recommended starting with 11.5 grains, for around 1700 fps. I also have 8 lbs of IMR Blue. Since some of the other forums advocate Alliant Blue Dot for reduced loads, I thought of using it - but the more I consider the matter, I'm leaning towards 4759.

[Green Frog]

Remember, to make the 220 be… SWIFT, you’ll be using relatively hot loads to send that bullet. Downloading and worrying about avoiding barrel wear kinda defeats the purpose of the round. OTOH, mild loads in your rifle will make it last a lot longer even if you give up some of the advertised performance. With that in mind, 4759 sounds like a really good idea.

Froggie

[Bill*B]

Yes, and I should be embarrassed to ask a jacketed bullet question in a cast bullet forum - but I have found honest hands on data here - real world experience as opposed to theory. I’m grateful for that and hope that I will be forgiven. My Swift has a 1 in 8” twist and I think of it as a pleasant shooting medium game gun, rather than the fire breathing varmint destroyer (and, Lord, what a 3800 fps 50 grain bullet can do!). A mild 70 grain Speer that replicates the old .22 Savage High Power is more to my taste - but really, most of my shooting is at the range, rather than in the field. Hence my angst about barrel saving target loads.

[Larry Gibson]

Thanks, all! I have several pounds of 4759, so based on your experiences, I might as well use it. I was thinking of the .220 Swift (don't laugh, please). Speer actually published - and the loads are still online - .220 Swift loads using 4759. With a 55 grain bullet, they recommended starting with 11.5 grains, for around 1700 fps. I also have 8 lbs of IMR Blue. Since some of the other forums advocate Alliant Blue Dot for reduced loads, I thought of using it - but the more I consider the matter, I'm leaning towards 4759.

With the 8" twist on your 220 Swift rifle you probably will find 1700 fps with a GC'd cast bullet to be the top end velocity/RPM for the accuracy you may be expecting. You might want to try a faster burning powder such as Unique and drop the velocity down in the 1400 - 1500 fps range.

[Bill*B]

Good point. The fast twist is a plus for jacketed, but an overall negative with cast.