H110 works fine throughout the 300BLK's subsonic to supersonic range (though not sure if there are any temperature/positional sensitivities). It has the benefit that it can be used for 357 magnum loads as well.

You said you wanted flexibility. A little more restrictive, but if powders get hard to find another option is CFEBLK. Be aware that if you try CFEBLK, it seems to like to be close to compressed both in terms of getting consistent accuracy and cleaner burning.

 

H110 works fine throughout the 300BLK's subsonic to supersonic range (though not sure if there are any temperature/positional sensitivities). It has the benefit that it can be used for 357 magnum loads as well.

You said you wanted flexibility. A little more restrictive, but if powders get hard to find another option is CFEBLK. Be aware that if you try CFEBLK, it seems to like to be close to compressed both in terms of getting consistent accuracy and cleaner burning.

You're absolutely correct on 'compressed powder charges'. Both the Hornady & Nosler manuals lists compressed powder charges, for instance; Nosler reloading guide #8, pg 436, 110 gr bullet using IMR 4227, all 3 listings are compressed powder charges. For H110, the max charge is compressed. Reloading manuals express the powder as a %(percent) of case capacity, for a particular manufacture case. I've used compressed charges a number of times in the past. Of course, I 'always' start about 3% less and work up from there. We want to keep our fingers/hands and faces in tack, as well as our firearms in one piece!

 

Actually most loading manuals and powder companies recommend -10% when starting new loads.
But the BO is basically a pistol cartridge so the pistols powders are the primary candidates.
300MP is the Alliant near equal fir 110/296.
110/296 has carried the warning of not down loading in the past.

 

What's your platform? What's your application?

Are you punching paper with an AR rifle? Are you hunting?

Do you want to use a suppressor?

I've heard that Hodgdon 300 BLK is a fine propellant for most work.

 

AR platform, some paper punching, and occasionally, taking Coyote's, on friends & relative's ranches. The powder I choose must be flexible enough to use for 'other' cartridges I reload. I don't expect miracles, but just as long as I'm spending the money, I require my powders to be 'flexible'!

 

We are talking a large search space here. I do not know what you reload, your platforms and projectile combinations.

I would recommend the newer "small" cartridge offerings by Hodgdon and others. They tend to be more versatile than older propellants. 300 CFEBlk, and the like might work.

I would not recommend using most pistol propellants in rifles, especially AR pattern firearms. You will probably be disappointed by cycling issues.

For some reason Hodgdon recommends pistol powder.

Reloading Data Center – Hodgdon Reloading Data Center

www.hodgdonreloading.com

 

For some reason Hodgdon recommends pistol powder.

I use pistol powder in bolt action rifle 'youth loads'. My go to powders have been Trail Boss and Red Dot. They work great with 30-06 youth loads.

My experience in using pistol powder in AR platforms has been mixed... often the action does not cycle. Port pressure impulse is not enough to cycle the action.

Safety isn't a concern..... making the thing run is a concern.

I went to the trouble of checking out the Hodgdon site....

The platform uses a 16" barrel, 1:8 twist. No mention of the test device, if it was a Universal Receiver with barrel or a firearm.

Your mileage may vary....

 

A little more restrictive, but if powders get hard to find another option is CFEBLK.

BLK is really good stuff. It was developed for the .300 BO. If you can't find any, AA 1680 is also very good, and may have been developed for the .300BO, it's nearly identical to BLK.

 

BLK is really good stuff. It was developed for the .300 BO. If you can't find any, AA 1680 is also very good, and may have been developed for the .300BO, it's nearly identical to BLK.

Good call on AA1680. For some reason, it seems to be a hair better for subsonic semi-auto extraction without a suppressor than H110 or CFEBLK. Not much, but some, for same FPS-rated loads.

 

Good call on AA1680. For some reason, it seems to be a hair better for subsonic semi-auto extraction without a suppressor than H110 or CFEBLK.

I built a pair of .300 Hamr's with Wilson tubes, 1680 and BLK will both turn in sub MOA groups at 100yds with Speer, Hornady, and Sierra bullets, W296, not so much. At the moment, Precision Reloading has AA1680 for a half decent price for anyone in need.

 

The 300 Blackout cartridge is unique and resembles a 30 Carbine more than it does common bottle neck rifle cartridges. As such, it uses the same slow burning powders as a 30 Carb or magnum handgun cartridges such as a 327 Fed Mag, 357 Mag, 41 Mag, 44 Mag or even 410 shotguns.

In the overall scheme of powder burn rates, there are fast burners for light target handgun loads, then there are medium burn rates for mid-velocity handgun loads. Slow burning magnum powders for handguns are at the beginning edge of fast burning powders for rifles. The 300 BO falls in the unique "magnum handgun" category .... not slow enough burning to be called a rifle powder and not fast enough burning to be called a normal handgun powder. The powders that produce the highest velocity in a 300 BO without exceeding the max chamber pressures are the slowest burners like Accurate 1680. The fastest burners like AA #9 develop the slowest velocities with the highest chamber pressure. The traditional Magnum handgun powders are the most versatile. These include Alliant 2400, Lil'Gun, Win-296, H-110, and IMR 4227.

I have been using W-296 for decades and have found it to be very predictable, accurate, and universal for all magnum handgun cartridges so I would buy it for 300 BO without hesitation. It works for all listed 30 cal bullet weights from 110gr to 225gr.

When using any of the slow burning powders, filling the case to at least 75% is essential to prevent squibs. Assuming a 150gr bullet, the 75% risk area would be 12gr or less of W-296 in the 300 BO, which uses from 12.7 to 16gr of W-296 so it will never fall into the risk area for squib loads. W-296 will maintain enough barrel pressure for gas operated actions, so it should meet all the criteria for a 300 BO and virtually all Magnum handgun loads from a 327 Fed Mag to a 45 Colt Ruger Only. It's also a great 410 shotgun powder.