300 Blackout Kick-Off: Gavin’s 16″ AR-15 with Anderson Upper

300 Blackout has been on my “list” for a LONG time- but sometimes life gets in the way. Well now it’s time, and I’m going to “go big” with this fun cartridge including rifles, suppressors, reloading, ballistics, and more (please leave a comment with your ideas!). To start things off, let’s take a look at the AR-15 I put together using an Anderson Manufacturing 16″ upper, and Sharps Rifle Company lower!

Anderson 16″ 300 Blackout Upper

I’ve built a few AR-15s with Anderson lowers, and they have always performed well. So when it came time to start shooting 300 Blackout, I thought I would give their uppers a try! Talking with Anderson, it sounded like the best “all-rounder” would be a 16″ setup (partially due to various legality issues) with a pistol-length gas system. Why a pistol-length gas system? With small powder charges, you need to maximize dwell time (the elapsed time which the bolt carrier is pressurized) in order to ensure reliable functioning. The shorter the gas system length, the more dwell time, and that’s where the pistol-length gas system comes in!

Fog Ammunition did an article on this which is an interesting and short read: (click image below to read article)

So I ended up with a complete upper from Anderson with the EXT handguard:

I took an existing lower from the “AR-15 library”, my 25-45 Sharps Rangemaster, and put it together with the Anderson upper. The result? A pretty nice looking business-first AR-15! The Vortex Strike Eagle 1-6x24mm scope works really well for the close-range shooting I’m doing with this rifle.

Initial Range Results

I’ve only had this rifle running for a few days now, and I’ve already tested it with the following ammunition:  (All loaded by myself, I’ll share more on ammo in my next post!).

In case you didn’t know, Capital Cartridge has once-fired 300 blackout brass!

So far everything has run 100% with the exception of some magazine issues related to my 190 grain subsonic load (barely fits in the magazine). The only issue here was stripping the first round, and I may have loaded the magazines improperly (without enough care pushing each round back). There have been a couple times when the bolt has not caught (back) on the last round- but only unsuppressed, and only two times in several hundred rounds of testing. On that note- this rifle has an adjustable gas block- and I haven’t even touched it yet! So between the adjustable gas block, different bullet options, and load adjustment (when reloading) there area LOT of tuning options for this cartridge and rifle.

What’s Next

There’s a lot to talk about related to 300 Blackout! Here are some of the things I plan to cover:

  • Rifles and suppressors (will look at this long-term)
  • Reloading, gear, and components
  • Ballistics
  • Shooting scenarios
  • [insert your ideas- forming 300 Blackout from 223?]

Lots more coming, so make sure you’re subscribed!



5 thoughts on “300 Blackout Kick-Off: Gavin’s 16″ AR-15 with Anderson Upper”

  1. I was looking at loading sub-sonic 300blk with Missouri Bullet Company’s 245 grain hi-tek bullets – they are easily 1/3 the price of other projectiles. Where would you start?

  2. Great to see you doing work on this cartridge. I’ve been really interested in finding reliable hunting options for the 300 Blackout. I know the Barnes 110 Tac TX is considered the go-to round for things like hogs and white tail, but what about the Hornady SST in 125 or the Nosler 125 BT. Can you get reliable expansion for these at 300 Blackout velocities? Are there other projectiles worth considering?

    1. Primary Arms makes some really high quality “budget” red dots, prism scopes, and magnified optics specifically for 300 Blackout (and 7.62×39) with etched glass ACSS (advanced combat sighting system) reticles, bullet drop compensation, and lifetime warranties.

  3. I’d like to see what you think about various 300 BLK optics, too. Also curious if you’ll delve into coated cast lead bullets. I’ve had some accuracy issues with those, not that they’re intended for match use, but would be interested to see if you found similar results. Thanks for what you do here!

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