Another Stupid 300BLK question....

[minmax]

What is the lightest cast boolit without gas check you would shoot? What is the lightest with GC?
The reason I ask is I got a great deal on a 16" barrel w/carbine length gas tube, before the blackout craze.
I have had it setting around and never built an upper for it. Now I have all the parts and figure I should put it to good use . I did get an adjustable gas block. I bought this barrel before I knew that I should have gone with a shorter barrel and a pistol length gas tube, so I could shoot subs. This was also way before the Sig pistol brace. I know al my answers are probably at 300blk.com, but I trust you guys more.

[Jupiter7]

I wouldn't try any without a gas check unless they were over 200grs and subsonic(around 30k+ PSI). Supers are same spec as .223(55k psi)and it's not hard to get there when trying to get gun to cycle. Personally I like the 150-160grn range, the lee 312-155 works as good as any.

[popper]

I shoot a 145 & 150 PB @ 1700 OK, 1:7 carbine. 1400 should be easy. I save the GC for the 308. It will depend on the mould you choose. COD & LEE BT sub don't have a good RAP.

[ipijohn]

You won't need the adjustable gas block on carbine length gas. I'm currently shooting 150gr+ w/GC full throttle with cover with a nickel accuracy at 50 yards. I've not shot plainbase, and not sure its a good idea at the pressures the BO works at (other than subs). Powder coating may work in place of GCs.

For about a year I have been shooting the Lee 312-155 GC & Powder Coated on the driving bands and base only. I shield the bore riding section because I had trouble with some not going into battery when the bore rider was PCed. Shooting A1680 at 1950 fps. Using a 1:8 twist 16" carbine length gas. They group at a little over an inch at 100 yds.

[Quiettime]

Second what ipijohn said about PC. Had it happen with some tumble PC'd NOE 247's. I ESPC now or just tumble lube them.

My carbine length would not cycle subs until I changed to a half-round bolt carrier (Old Colt) and put a couple hundred rounds through it. I also hand cycled it several hundred times. It works pretty good now with my sub loads using 4227.

Some people just open up the gas port. Carbine wants more gas usually.

I love casting and shooting this boolit. It really smacks the hell out of steel even at 130 yds. I've been crimping in the crimp groove but I may experiment with seating a little deeper to see if it makes for more reliability. Still get a short stroke once in a while and I can't use my load in PMags. I don't use gas checks and have the plain base mould with the hollow point cavity (HP expands a lot even sub)

HTH

[detox]

Sizing your lead bullet as large as possible (.0005 under free bore diameter) works best for good accuracy. Hard linotype alloy will grip the fast twist rifling best. I would use the Harris designs by LEE....either the 155 or 160 version.

[bruce drake]

I have a 20" 300BLK barrel but with a carbine-length gas system so take this advice with a little guidance that your results may be different than mine. I don't often shoot plain-base loads at all in my AR Upper as I built it for use with super-sonic loads. I have a 130gr load that is reportedly great in bolt-rifles as a sub-sonic using a shotgun/pistol powder and I know its a nice rabbit round at 25 yards.

Lyman 311359 120gr spire-point gas-checked mold: This mold was originally designed for the 30 Carbine and it works excellent in my rifle with a 1-8" twist barrel.
24.5gr WC-844 (H-335 starting data minus 10%) pushes this bullet out at 2000fps.

LEE CE Harris designed 155gr spire-point gas-checked bullet: Mr. Harris designed this bullet mold for use in an SKS. It is an excellent bullet for the 300BLK out to 200 yards.
22gr WC-844 (H-335 starting data minus 10%) pushes this bullet out at 1900fps.

Lyman 311410 130gr bevel-based, plain base bullet: Designed also for the M1 Carbine and due to the plain base, I would recommend not pushing it over 1600fps to prevent leading. I have not built this load to function in my AR but this load is a great load to finishing fireforming new cases and it will drop rabbits very well. It will not function the AR and will not eject either. You will have to operate the rifle as a straight-pull with the charging handle.
8gr Red Dot pushes the bullet out at 1500fps with my 20" barrel.

I hope this helps point you in a direction to start.

Bruce

[Pink_Vapor]

Second what ipijohn said about PC. Had it happen with some tumble PC'd NOE 247's. I ESPC now or just tumble lube them.
HTH

Help a noob, what's ESPC?
I've a 1/7 10" supressed 300BLK that I'm soaking up info to hopefully only purchase one mold for subsonic hunting & plinking rounds. I'm thinking PC is the way to go to minimise can buildup.

[minmax]

ESPC = Electro Static Powder Coating

From Wikipedia, the free encyclopedia

Powder coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form. The coating is typically applied electrostatically and is then cured under heat to allow it to flow and form a "skin". The powder may be a thermoplastic or a thermosetpolymer. It is usually used to create a hard finish that is tougher than conventional paint. Powder coating is mainly used for coating of metals, such as household appliances, aluminium extrusions, drum hardware, andautomobile and bicycle parts. Newer technologies allow other materials, such as MDF (medium-density fibreboard), to be powder coated using different methods.