Reduced loads with SR4759

[BD264]

These bullets are not powder coated. I cast these several years ago for my 6.5x55. Target was at 25 yards or so.20210404_212348.jpg

I can definitely see going higher, there were no signs of pressure, lots of blow back and case sooting due to a lack of pressure. Of course, shooting cast bullets is way different than shooting a jacketed bullet. But I figured this information would be helpful to others.

[LR1955]

These bullets are not powder coated. I cast these several years ago for my 6.5x55. Target was at 25 yards or so.[ATTACH=CONFIG]17738[/ATTACH]

I can definitely see going higher, there were no signs of pressure, lots of blow back and case sooting due to a lack of pressure. Of course, shooting cast bullets is way different than shooting a jacketed bullet. But I figured this information would be helpful to others.

How about informing the guys about the difference between cast and jacketed bullets when using reduced loads of fast powder.

[BD264]

In a basic sense as I understand it. A cast lead bullet or boolet if you may, takes less pressure to go "x fps" than a copper jacketed bullet. Lead being more "slippery" than copper being pushed through a barrel.

In otherwords, I cannot guarantee that 4759 will push a copper jacket bullet out of a barrel without further testing it. So take my data with a large grain of salt, I am not really a fan of pushing jacketed bullets at sub load levels.

That cover it LR1955?

[Mad Charlie]

In general, lead alloy bullets have less resistance to starting and engraving into the throat and rifling and less friction traveling down the barrel, compared to a copper jacketed bullet, which changes the entire pressure curve, compared to jacketed bullets. Jacketed and lead bullets are two different ball games, sort of like baseball and softball, related, but different. There a lot of variables, alloy, lube, coating, sizing, and such.

[LR1955]

BD and MC:

Covers it great. Thankyou!

As for 4759, its bulk density is pretty low so more of it can fill the case than the shotgun powders we used to use for cast bullets. That's why I really liked it for cast bullets. Wish it was still made.

Not sure myself how it will react to jacketed bullets for the reasons you guys say. Could work fine and may be one of those powders where an extra half grain becomes a bad situation. Just not positive but if I wanted to test loads at 1700 fps using jacketed bullets I would probably opt to start with something like a case fill of 4350 and use it as a baseline for other powders.

Thanks again for explaining it!

LR55

[Fess]

Does anyone know how similar Accurate 5744 is to the old 4759? It also uses the 40% capacity loading for reduced charges. I think that it is made by General Dynamics in Canada, where some of the IMR powders are currently made.

[BD264]

4759 and 5744 appear next to each on most burn rate charts.