HandLoading 300 BLK, Anyone?

[Toprudder]

I doubt anyone here has run into what I call the "LilGun Phenomena". LilGun is a great powder in all of my B&M Super Shorts, .500, .474, and 458 calibers. But, at some point in compression, LilGun actually goes "backwards". The more you add, the less pressure you get, and the less velocity. A strange occurrence I have never experienced with any other powder.

Actually, I experienced something very similar with 300-MP in a 357mag 5" barrel. I worked up a wide range of charges, all the way up to the max charge that Alliant listed (their data was from a 10" barrel - more on that later). I got the expected increase in velocity up to a point, then the velocity appeared to go down some, but basically stayed flat through the last 2.0gn of charge level. 1200fps with a 158gn bullet, which was no better than other powders I tried (N-110, H-110, 2400). I did not understand, since both Hornady and Alliant showed much higher velocities, compared to other powders. (Hornady data was from an 8" barrel). I set aside the 300-MP and moved on.

Later, I purchased a 16" Rossi in 357mag, and though I would revisit 300-MP. I'm glad I did. I saw a linear increase in velocity all the way up to max charge, which was just short of becoming a compressed charge. I think it was around 150fps faster than anything else I tried, with no high pressure signs, and using non-magnum primers. Accuracy was great @ 50 yards.

For some reason, 300-MP really shines with longer barrels, but there is no advantage at all in using it for short (5" or less) barrels. Something about the burn characteristics, it does not behave like other powders I have tried. Even with slow burning powders, I still get SOME increase in velocity as the charge increases, even with short barrels.

Later, I tried 300-MP in a 44 mag rifle, and I saw similar characteristics to what I observed in 357mag.

I've been under the impression that there is some similarity between Lil-Gun and 300-MP, and your observations seem to confirm that.

 

[Goofyfoot2001]

Actually not that good. Caliber does make a difference at 1000 fps....... My opinion .308 at a 1000 fps ain't hitting on much, not in Terminal Performance terms, and I have tested them....... Personally, I could give a rats ass about SubSonic and Suppressors. But when we did the NFA Trust a few years ago, my boys wanted to add suppressors. We did two. I got interested enough to try some things and came to the conclusion for terminal performance at SubSonic Velocities, you are going to have to work damn hard to be a 45 ACP 230 grain anything. And, it comes like that straight out the box, is .451 caliber to start with, and expanding 45s work at those velocities. You have to have special designed .308 caliber bullets to get any sort of Terminal Performance, and even then sometimes comes up short. Run of the Mill basic .308 caliber subsonic is not hitting on much if anything at all............ You are not even going to drill a hole very far without special solid designs, common spritzers will not expand, pointy solids are not terminally stable, and will flip and go off course....... I know there is a lot of SubSonic fans around for the 300 BLK, I am not one of them, or any other sub 308 for that matter. Make it a 45 ACP, and you start to have something worth working with....... Now if you are just shooting and plinking that is one thing, but Terminal Performance is quite another.

True, but when I load up 30 rounds in my .45 the mag keeps hitting my bad knee.

 

[Michael458]

then the velocity appeared to go down some, but basically stayed flat through the last 2.0gn of charge level.

Normally when one reaches peak pressures, velocity does go flat at that point, but you put more powder in and pressure continues to go up, pressure does not go flat........ With the LilGun on several occasions in other cartridges and in particular the 50 B&M Super Short, the more I put in, velocity not only stayed flat, but went DOWN, and so did the pressure........... This is what I have seen a few times with LilGun, I personally have never seen another powder do it, none used here. I never used 300-MP.... so don't know anything about it. Powder can be extremely interesting to work with. And many times quite a challenge. Recently with the 358 MGP I tried some blends with LilGun and WW 296 mixed, but was not successful with meeting velocity, reached pressure max too fast. With that one need to look more at CFE Black, and maybe a dose of WW 296. I never blended any with 300 BLK, I don't think one would gain much, but never put a lot of thought into blending 300 BLK........ Most of the blending I have done has been big bore cartridges......

True, but when I load up 30 rounds in my .45 the mag keeps hitting my bad knee

HEH........ Yeah, I can see where that would be an issue, good point, will have to remember that........ LOL......