.223/5.56 heavy bullet subsonic load data

[jstein650]

I've done a few searches, but just didn't find what I'm looking for.
I will be putting together some sub-sonic loads for my AR, 1:7 twist, using 80gr tipped bullets. Published data for this is pretty scarce from what I've been able to find. I'm thinking I'll be needing something in the slow pistol range of powders. I'd like to just hit 1050 fps.
I have on hand IMR4227, All. 300MP, & Vectan Ba 6 1/2.
I don't really care if it cycles on its own or not. I can rack the thing manually if I need to.
Anyone out there been here before?

Thanks.

 

[Blue68f100]

If I recall the 80's are to long to fit the magazine, so they must be hand fed. The 77 gr will fit the magazine. But going sub sonic you will have plenty of room for powder. Have no Idea on the load though.

 

[Manny]

Found this thread that talks about loading 77gr SMK's w/ 5.7-5.8 grains of Trailboss to get the velocity you're looking for.
http://www.silencertalk.com/forum/viewtopic.php?t=3088