300 Blackout


Well-Known Member
Remember that last time I said I was building my last rifle, well I lied! My 8 year old deer hunted last year with my AR in 223. AR's work great for kids because they are short and adjustable. I have killed plenty of deer with a 223 (nothing big mostly during our doe only season) but I view it more as a expert round than a starter round. So I went looking for a replacement. My kid is a little skinny (kind of like his old man) so I have to keep the recoil to a minimum. I think I have found a pretty good match = works in the AR platform, light recoil, double the bullet weight of the 223. Muzzle velocity of 2350 fps with 1350 ft-lb of energy. Almost gets you to 30-30 performance. Just built a new upper so I can use my existing lower. Goofy looking little round but on 100 yard max deer I think it will be a good one.

I thought long and hard about adding an upper in 300. I ended up going with a 6.8 instead. I have a Mini-30 so it was hard to rationalize duplicating 7.62x39 performance. Awesome little performers at woods ranges. If I lived in a free state where a suppressor was a possibility, I would have gone with the 300.
I liked the 6.8 ballistics better, and also looked at the 6.5 Grendel. The selling point for me for the 300 was the ability to use the same bolt carrier group on both my uppers. Cheapened up the build.
Goal was light and easy to handle
Anderson Slick sided upper
16" KAK Stainless barrel
Matrix Arms 9" handguard (from Joe Bob Outifitters)
Lo pro gas block
Carbine length gas tube
Cheap knock off scope mount off amazon
All in for around $280

My existing AR equipment:
DPMS bolt carrier group
CMMG lower
POF 3.5 lb trigger
Magpul buttstock
Hogue grip
Scope is a cheap bushnell 1.5-4 x scope (low power = easy for the kid to use)

I thought about a 300 BO upper earlier this spring. I have a 30 cal suppressor on order that I'm waiting for the paper work to go through for, and was trying to decide on a gun to put it on. Everyone says 300 BO "is almost 30-30 performance", but when you really look at the numbers, it's not really that close. A 30-30 out of a typical lever gun is 1900 ft-lbs of energy. 300BO is about 1350 ft-lbs like you said. I still may build a blackout in the future, but for now I ended up getting a short barreled 308 bolt action instead. I'm looking forward to shooting it with a suppressor.

I you whack a deer with your blackout, report back on how it performed. I would definitely like to know.
Yes muzzle velocity for a 110 gr blackout vs a 150 gr 30-30 is about the same. You gain ft-lbs with the additional bullet weight. No more powder than can be in the little case it is amazing they can ring as much out of it as they do. Hopefully I will have a report come fall.
My grandson killed his first deer with my CMMG Piston AR with a .223 round. I have thought about a .300 BO upper for myself but then I look at how seldom I even shoot a gun and the fact that ammo is extremely hard to get when you don't load your own... Heck a Shotgun with a slug and a muzzleloader would probably take care of any hunting I do because I don't have anywhere I can hunt I can see more than 100 yards (food plot) and usually much less (Timber)...
I may buy some dies for this one. Got a box of 20 on sale for $17 the other day! The Barnes cartridges I plan on him using for deer are $35. I inherited this disorder from my dad, he was always buying guns and MIGHT shoot once a year. I have guns in the cabinet that I have never even shot! Don't tell the wife......
Like azeeb, I too can't wait to see the results this fall. I think the AR platform is the best rifle for kids. It's adjustable and doesn't kick much.
I may buy some dies for this one. Got a box of 20 on sale for $17 the other day! The Barnes cartridges I plan on him using for deer are $35. I inherited this disorder from my dad, he was always buying guns and MIGHT shoot once a year. I have guns in the cabinet that I have never even shot! Don't tell the wife......

With a disorder like that, how can you have a thread about the last rifle you'll ever need?:)
I inherited a bunch of my dads and my grandfathers guns that I have never shot and may never shoot... I should shoot more but time is always my enemy on that deal...
If you're going to wind up reloading anyway, a 308 or 30-'06 bolt gun will let you tailor low-recoil loads while your son is young and then step them up as he gets bigger. My wife has harvested her last thee deer with a 30-'06 shooting handloads I put together with H4895 and the Nosler 125 Ballistic Tip bullet at around 2,600fps. The recoil is less than a muzzle-loader with 100 grains of powder and the performance of that BT, at reduced velocity, is excellent.
Remember we are dealing with a 45 pound 8 year old. Even reduced loads are a lot for a man that size. When he gets bigger there are plenty of full size deer guns waiting in the cabinet. The 300 BLK recoil is just a little more than the 223 (and that is without a break). Also the collapsible stock lets me get the length of pull down were it needs to be.
I built a 300blkout pistol this off season to replace my 223 hunting rifle. I also "need" another 300 so its not lonely so i have been looking at the Ranch from ruger or the handi from H&R both are threaded for my hearing pressure and have 20" barrels. i have a 30cal can and subsonic 300 ammo, i'm hoping it helps the spookiness this year. I have some maker bullets that a local reloaded made up to test they really work well on hogs.
When my son was that age I started him on a T/C Encore. He learned to shoot it and handle it with a 22-250 barrel and a soft reload. When the season rolled around I put a 243 barrel on. He made a perfect shot and never noticed the difference. I love the Encore platform. We both hunt with Encores during muzzleloader and rifle seasons, just switch barrels. ARs are a lot of fun too. They can be addicting.
Like Sheep Dog, I bought a T/C Encore and put on a Choate adjustable stock for my son and with the can the recoil is almost non existent. My son, now 7 shot his first buck/deer 2 seasons ago with this combo and dropped the deer in its tracks, last year he got a doe (DRT) and these two bucks, both excellent lung shots and deer ran no more than 50 yards. When I first got this set up I wanted to see if the round would be suitable for a humane kill, I shot a doe at 188 yards, DRT, I was sold, this is an effective little round. I highly recommend it as an intro for young hunters as it is a pleasure to shoot and really builds confidence.ej1.jpg ej2.jpg
In addition to the above, I liked the 300BLK so much that I bought an Ambush (Daniel Defense) Blackout and it is now my go to deer gun for 200 yards or less, the 270wsm collects dust now. My goal this year is to attempt to harvest a deer with it subsonic using the Lehigh ME or CF bullet, favoring the Maximum Expansion at this point in the game as it shoots great and know of several people who have had good success with it, hopefully I have something worthwhile to report in a couple months...
I think the 300 Blackout in the AR platform is an excellent choice for a small person to deer hunt with at close to moderate ranges. The fact that the stock is adjustable without permanent modification is half the argument, and new shooters probably need to keep their shots to 100 yd. or less anyway. That said, I'm about to re-barrell a .223/5.56 to 6.8 for my night time hog killer. I just like the 6.8 for my purposes.
I've been loading it for 20 years as the 300 whisper in TC contenders. Buy the dies, cut down 5.56 Lake City brass. You can load hotter with lc because the case head is tougher than the 221 fireball case head. We took 20 or more deer with the whisper, but they would most times run a long way, with out much blood so we only used it on field shots. 110 grain Barnes X. Some will disagree.