Ar- 300 bo cast loads info needed

[sixgunner452]

Fellers, I need to be schooled on a couple points on the 300 BO. Please.

I ordered a 10.5'', 1-8 twist, pistol gas system AR barreled upper in 300 BO. Which I have zero experience, in this caliber. I also ordered the Lee 3 die set. Have 180 1X cases incoming too.

I want to shoot 150-175 grain, CAST bullets. Already own the molds. The 175 throws, GC and PB bullets, 150's are PB. Can I get them going 1200 to 1700-ish with 2400 or similar powder? Do I have unrealistic expectations? Do I need exotic powders?

Will they run going that slow? Do i need a heavier bullet? I am NOT apposed to heavy bullets.

Do I need the "special" 300 BO magazines?

Many thanks, in advance. Randy.

[barkerwc4362]

Get some 300 BLK specific mags. Lancer makes 20 rounders that are utterly reliable and Magpul currently makes 30 rounders. With either of these you will have no functioning issues. .556/223 mags can be problematic.

Bill

[sixgunner452]

barkerwc4362, Bummer. Kinda hurt my feelings. I was hoping if I stuck to middle-of the-road wt boolits I would not need specialty mags. I know they are only 15 bux, BUT I try to apply the KISS principle to all aspects of my life. Will have to investigate the 300 BO mags. New toy. New expenses. Thanks, Randy.

[sixgunner452]

Any takers on the 300 BO loads info using CAST Boolits? Thanks, Randy.

[imashooter2]

Your velocity targets and boolit weights are certainly in the common 300 BLK range. I don’t see a lot of load info on 2400 with heavier bullets, but Lil Gun, IMR 4227, AA 1680 and RL7 all have a fair bit of jacketed data that I wouldn’t hesitate to use working up with cast. Most users powder coat, but I load conventionally lubed boolits.

[imashooter2]

The requirement for 300 BLK specific magazines really depends on your boolit profile. If your boolits are larger than ~.250 diameter where they contact the internal rib of the .223 magazines, the cartridges won’t stack correctly and may bind when magazines are fully loaded. I had no luck using Colt aluminum 20s with the Lee C312-160-2R. Lancer 20s fed them flawlessly.

I have seen posts that claim filing down the forward rib in Magpul magazines solves the problem. I can’t see why that wouldn’t do the job, but I paid for 2 Lancers and never looked back.

[sixgunner452]

Sounds like Lancers are the way to go.

[endwrench]

You shouldn't have any problem developing a reliable load with the components you're talking about. I've found some cast designs without much of a oglive can be problematic in the 300. Most of my problem loads are in subsonic variations though.

Sent from my SM-T380 using Tapatalk

[sixgunner452]

endwrench, thanks for your input. Sounds encouraging. I also have some Vectan 6.5 I thought I might try. Anyone out there tried that powder and 300BO? Randy.

[sukivel]

barkerwc4362, Bummer. Kinda hurt my feelings. I was hoping if I stuck to middle-of the-road wt boolits I would not need specialty mags. I know they are only 15 bux, BUT I try to apply the KISS principle to all aspects of my life. Will have to investigate the 300 BO mags. New toy. New expenses. Thanks, Randy.

All I use are 5.56 pmags and have never had a problem. I load 155 and 230 grain cast bullets with 4227. No feeding problems.


Sent from my iPhone using Tapatalk

[sixgunner452]

sukivel,That is good info on the mags. I did watcha Utube vid showing how to remove the ribs on G2 PMags.

[sixgunner452]

I am still in need of load data on a 170-ish cast boolit and 2400 powder. Any Takers? Thanks, Randy.

[imashooter2]

Alliant doesn’t list any data for 300 BLK. Nosler lists 9.5 grains max under their 220 grain jacketed. Best I could find.

https://www.nosler.com/300-aac-blackout

[sixgunner452]

imashooter2, thanks for the load data. Randy.

[sutherpride59]

I have used H110 for all of my super loads and I have had decent results with it in my subsonic loads. I am currently working up a load for my 9" pistol in 300 but I didn't venture out much with powder choices. H110 was a popular option and worked well in my 357 so I bought an 8lbs keg and never looked back. I have also used WIN231 for my subsonic quiet rounds that I didn't mind a lack of cycling in.

[BJK]

Try your 5.56 mags and see if they work. There is a rib in them that might be a problem, There is interference with some cartridge profiles. Will it be a problem for you? I dunno. I thought it was hogwash, bought one Lancer mag and saw the difference immediately in observing the "obstruction". Again, will it be an issue? Try it and see.

There is also a potential issue with the heavier bullet and springs with 5.56 mags not pushing the cartridges up quickly enough to be picked up.

But again, I'd try what you have and see what happens. Or if you can use more mags just buy the mags made for the cartridge and be done with it. The cartridge was designed to be used with only a barrel change, and everything else being the same. Just sayin'.

[sixgunner452]

Thanks to all that have offered info. I have never used H110/296. I guess I am old school. I've always used 2400. I know it is not as full throttle as H110 loads, but it has always worked good enough for me and my cast loads. Might have to pick up a LB and see. Thanks again, Randy.

[sixgunner452]

Any of you have n opinion on H110 vs 1680?

Subs/ Supers. Light and heavy Boolits>? Thanks, Randy.

[popper]

From GRT powder selection (for my seating depth):
--------------------------------------------------------------------------------
A T T E N T I O N - A T T E N T I O N - A T T E N T I O N
--------------------------------------------------------------------------------
Depending on the setting of the limiting tolerance windows, the charges can
exceed the specified maximum pressures, or have no meaningful, or even
a dangerous value. Please check a load prior to use for plausibility.

The order of the list depends on the composition of the powder list.
--------------------------------------------------------------------------------
propellant mass load ratio pmax v0 E0 burnt eff. BT BLT recoil
grain % psi ft/s ft-lb % % ms ms ft-lb
Alliant Reloder 7 15.30 99.6 ▼27634 1363.0 701 74.9 26.6 1.0501 0.9774 3.57 Out of spec. tolerance
Alliant 2400 12.44 85.3 45017 1514.8 866 94.7 38.5 0.9130 0.8171 4.17
Hodgdon CFE-BLK 18.10 99.9 ▼44592 1544.8 901 86.0 26.7 0.8806 0.8063 4.80 Out of spec. tolerance
IMR 4227 15.30 99.6 45482 1574.6 936 84.5 31.8 0.8490 0.7866 4.74
Accurate 1680 17.46 96.7 50586 1590.1 954 78.5 29.3 0.8171 0.7612 5.01
Hodgdon H110 15.30 91.4 44974 1602.4 969 93.3 33.0 0.8546 0.7867 4.93

[imashooter2]

Any of you have n opinion on H110 vs 1680?

Subs/ Supers. Light and heavy Boolits>? Thanks, Randy.

From the data I’ve seen, 1680 seems to start near the upper end of the velocity band you are looking for. I’ve never used it though.

[1006]

I use 2400 with a plated 150 grain bullet.

14.5 of 2400 gives me 1839 FPS in a Ruger American Ranch, and it cycles the AR 16 inch rifle with a Carbine Gas system, but I find LilGun works best in the AR with 140 to 170 grain bullets.

[F_L]

Any of you have n opinion on H110 vs 1680?

Subs/ Supers. Light and heavy Boolits>? Thanks, Randy.

I use H110 for my supersonic BO loads, 1680 for subsonic. My supersonic loads are for 125gr J-word, 150gr cast HP. Subsonic is 215gr cast HP.

[sixgunner452]

1006, that's exactly what I was looking for. Thanks, Randy.

[sixgunner452]

I noticed 7.62X39 has similar case capacity. Anyone use this a starting load data? Thanks, Randy.

[sixgunner452]

Fooey, thanks for the intel. I need to get a heavy-30 cal mold. Randy.

[imashooter2]

LOL! One post and banned? He must have brought up the forbidden subject. :groner:

[sixgunner452]

imashooter2, I must have missed something. Please elaborate. Randy.

[sixgunner452]

Imashooter2. Please pm me forbidden subject. Randy