800-x, vs. SR4756

[puke]

800x is cool, but even when I trickle my loads perfectly, I get a fairly large velocity spread (I think at least 30 feet per second..don't have my data in front of me).

I noticed that SR4756 was right next to 800X on the burn rate charts.  I have some of that I have never opened, is there is a reason there is not any 10mm loads listed for it?  I would love to go away from 800x since #1 it meters poorly, and #2, even if I trickle to perfection,..the velocities vary quite a bit.    I was going to switch back to Power Pistol, but then I saw that SR4756 was right next to 800x ,. So I thought I would make a post here and see if anybody knows any info on it.  thank you in advance.

[AlinMi]

If memory serves me, I believe 4756 has been discontinued a couple years back.

[Muskrat]

I don't have any input on SR4756, and I'm no expert on gunpowders. But placement on the burn rate chart doesn't seem to have a whole lot to do with which powders are suitable for which cartridges.

I've got 10mm loading data ranging from #15 on the chart...Tightgroup, to #59...A9, but MOST of the powders in-between are not supported with any 10mm load data.

I can't tell you why that is, but interpolation would suggest that burn rate is just one of many factors that make a powder suitable for loading any given cartridge.

Good luck!

[The_Shadow]

The SR powders were single base powders if I recall...Hodgdon and Hornady Manual #6-#10 has some data for SR4756

[puke]

Thank you for that information. THe only hodgdon book I have is pretty old,. and my newer lymans and speer are silent on the sr4756. I think my hornady is  #3,.and there are some things that were not "a thing' yet when they wrote it.  I'll probably see how 4756 meters and use it up. Apparently it does sit alongside 800x in some of those handload charts.   

[RDub01]

Hi
The main difference between the two is 4756 is single base and 800-X is double base.

I did a work up with 4756 with 180gr Hornady HAP bullets using a WLP primer; G20-SF stock.



8.8 grs was the heaviest charge I could find in all the data I looked at. This yielded 1146 fps. SD's were excellent.
Here is a data sheet;



The case expansion indicates there is some room to grow.. I didn't take it any higher.

With 800-X and a 180gr jacketed bullet, about 10 grains yields around 1250 fps
This is one of my pet loads;



Notice the 26 fps spread using a REM 2½ primer. I get good SD with the Rem primer with 800-X.  Expansion here is right at max, so not recommended to go any higher. I've found 800-X to be stable at this pressure.  Primers can make a huge difference with pressure in the 10mm. I believe the Rem primer to be the mildest of all the LP primers.

Anyway, hope this helps..

[oldman10mm]

Been reloading since the late 70s'. My foray into 357M and 44M was with 2400 but the stuff burnt 'too dirty' even with a heavy crimp. Back then the Remington / Dupont reload data indicated SR4756 could produce equivalent ballistics to 2400. Tried it and have been using it ever since because of its' clean burning properties. When it was announced that SR4756 (along with some others) was being discontinued, I started acquiring/stocking up. I use SR4756 for performance loads in 38sp, 357M, 44sp, 44M. When I got into pistols, SR4756 was the first powder tried. I use it for 9mm, 40S&W, 10mm.

[RDub01]

This is a continuation of what I started a few years ago;

http://10mm-firearms.com/reloading-10mm-ammo/sr-4756-workup-with-hornady-180gr-hap/

Today I took 4756 out a little farther using Magtech 180gr FMJ. I'm out of Hornady's..
Starline brass was used.




Started with 8.8grs and ended with 9.4grs.
Here is the expansion data;

8.8grs  .4338, .4335, .4335, .4337, .4332"
9.1grs  .4335, .4332, .4337, .4339, .4340"
9.4grs  .4336, .4332, .4343, .4342, .4344"

The Magtechs run a bit slower than the Hornadys.
So at 9.4grs I started running into expansion over the .4340" mark. So, at least in this Glock with the unsupported chamber, SR4756 maxes out at about 9.0, 9.1grs..
9.1grs shot the best group anyway.