300blackout build, what you know like and dont

[nagantguy]

We are about to engage in a build, doing two ar's at the same time, think mine will be in 300blackout. Never done nor fired one in this flavor. Those who have, would you recommend it, love it hate it. It'll be for cast and jacketed but mostly cast, eventually I'd like to get a can for it, it'll be a plinker, deer hog hunter coyote ect. The ar is not my favorite platform but after my stint in the marine corps and years of shooting them in hi power and 3 gun I am very comfortable and proficient with one. Like the 300blackout on paper and in the theroy but what do you think of yours? Already have a way to make brass and molds from 150-200 grains. Lots of jacketed. Would I be better served getting an encore barrel first to test with?

[Ford SD]

We are about to engage in a build, doing two ar's at the same time, think mine will be in 300blackout. Never done nor fired one in this flavor. Those who have, would you recommend it, love it hate it. It'll be for cast and jacketed but mostly cast, eventually I'd like to get a can for it, it'll be a plinker, deer hog hunter coyote ect. The ar is not my favorite platform but after my stint in the marine corps and years of shooting them in hi power and 3 gun I am very comfortable and proficient with one. Like the 300blackout on paper and in the theroy but what do you think of yours? Already have a way to make brass and molds from 150-200 grains. Lots of jacketed. Would I be better served getting an encore barrel first to test with?

Love it
Wish I had more time to shoot it
Jacket 150+-
Cast 165-175-185
Data on internet some of it is Hot from reliable sources
first loads with 150j and I ended up with 60 pcs of enlarged primer pocket brass ( looked ok when i shot it)
only noticed when reloading and you could put a primer on the desk top and press down with brass and seat it 3/4 or the way

[Electric88]

I like the 300blk a lot, and will love it a whole lot more after I finally get the suppressor I ordered for it! It really is a fun caliber, and if you reload it is quite cheap (provided you form your own brass). Otherwise, it can be a little pricey.

Also, since you plan on building, I would highly recommend a pistol length gas system with an adjustable gas block. This should allow you to shoot pretty much any bullet subsonic or supersonic. That is my experience though.

[osteodoc08]

I love the 300 BLK. It has decent ballistics for what it is. It will never be a long range gun.

With 125 Nosler BT, It is a good deer and hog gun.

It is enjoyable and with heavy subsonic ammo, very quiet and fun for plinking. Plus brass is easily aquired and easy to make.

[Boolseye]

I like mine a lot, for many of the reasons mentioned.
Very efficient low end high powered rifle, near 30-30 ballistics with
2/3 the powder charge. I shoot mainly cast, Lee CTL312-160 2R.
i can bounce slugs off the 100 yard gong with ease in my carbine.

[nagantguy]

This is exactly why I came to you guys, thank you, adjustable gas block and pistol length gas tube I've heard as good several times. Keep it coming, the good and bad.

[popper]

For yotes I would recommend the 7.62x40WT. Longer case and 2400 fps with 125 gr. Same barrel chambered to the 40mm case, 1:12. Love the BO for supers but have no need for subs. I like the 1:10 for 125-180gr. Most are rifled for subs 1:7 which will work at 16-1700 fps (150gr.) & heavy subs. With 125gr. your probably good to 200, 145gr. for me is good to 150 yds, after that drop is excessive. Mine is a carbine gas rifle. With my 145gr PB I'm in starting 30/30 jacketed range (2100 fps). Took 308 & BO pig hunting, should have left the 308 at home (2.5x the powder and 3# heavier). BO gets lots of range trips. Yes, I like it a lot! 10 or 20 rnd mags are great for pigs & yotes.

[Electric88]

If you do plan on getting into the 300blk, get onto the MiHec group buy for the 300blk boolit. It's been running for quite some time, but I am assured by others that it will be a phenomenal hollowpoint for hunting critters. It's a heavier boolit too, something like 230gr. Perfect for suppressor use!

[geargnasher]

I love mine. Can't see having one if not an AR variant or Mini-14, though.

Pistol length gas system is easiest and most versatile, but a little more harsh compared to carbine-length systems. I have both and put an adjustable gas block on the pistol-length system to manage the gas volume, though it doesn't fix the too-short dwell time. No big deal really, reliability is a non-issue once I got loads dialed in.

Get a 7 twist if you can and even slightly think you might use heavy subsonic loads suppressed.

I highly recommend the ACE design that now NOE is making, the 311-235 grain. Plain-based and cast of air-cooled watered-down wheel weights (about 12 bhn) both of mine will put an entire magazine full into 1.5 MOA at any distance if you do your part. Reloder 7 has been good for me with the subsonics and full-auto BCG and standard carbine buffer weight and spring.

A tip on magazines if you use long, heavy bullets: Forget steel ones. Get Magpul Gen III mags and file the nibs off the top of the bullet nose guide rails so the bullets don't bind going in or coming out of the magazine, and also so you can more easily seat a loaded magazine on a closed bolt.

I wasn't much of an AR fan until I built a 300 BLK. Loved it so much I built another one. With full-house 125-grain bullets they tend to recoil a little bit more than 55-grain .223, so not really the hot ticket for games IMO, but you can fix that with a good brake or suppressor and the muzzle blast will still be less than a .223 of equal barrel length.

Gear

[nagantguy]

Thank you geargnasher that's exactly the kind of info I'm seeking!!!' Looks like this project is a go, if I turns out I don't like the round/platform as much in reality as on paper I can always sell or trade it.

[popper]

I imagine you will keep it.

[kawasakifreak77]

Even though I'm not a huge fan of the AR, I had one in Blackout & it was a fantastic rifle. 100% reliable. Cast or j-words, factory or handloads, subs or supers didn't matter! Extremely versatile & accurate. I had a couple GI mags given to me that seemed to work fine with most anything.

Later though I sold it & dived into the AK world for my 30 caliber bullet hose needs.

My Blackout is a semi custom bolt action that I load subs for only. Fancy stuff like Lehigh fracturing brass bullets, tracers, AP, etc. Scary quiet. Like, "click....thump"

[Scout800a]

I really like mine. I've had good luck with NOE 311414.

[mto7464]

Have a 8.5 pistol length from Palmetto. Using a buddies suppressor and the Lee 235 it's sweet. The lee's drop small but after powder coating it brings them up about .003 so I then size them to .310. The front bands are still a little under that so its not a perfect bullet but the mold is inexpensive and they function flawlessly. I will not use anything but PC and Hitek with cast in it, especially suppressed. As much as I shoot it j bullets would cost me a fortune. PC on all my other boolits makes the noses oversized so I switched to Hitek with them and have no problems feeding now. Would like to get the NOE mold but can't bring myself to buy another mold. If I hunt with it I will just used jacketed. Have lots of those in .30. I am SBRing it and building a form 1 suppressor when my stamps get here so it will be a lot of fun. Make my own brass too from all the 223 I have lying around.

[nagantguy]

I'm assembling my lower now, I thought this caliber which I can readily make brass, and already have several molds for couples with PC would be awesome and very useful as deer pigs yotes and garden pests are my main quarry and 6 years of service tranning/familiarity with the ar platform, the build is a go! Thanks you guys for being my enablers once again.

[mto7464]

your welcome. You will love it.

[popper]

I tried Eco100 AC oil as a BCG lube - I like it. Not a lot of rounds for testing but it says on and is not messy like mobil1 or lith grease. Applied with a Qtip to the rail wear points. Inside of receiver is dry now, don't see an accumulation of dirt/residue. Doesn't blow crud into the buffer tube either.

[nagantguy]

Lower is together, now to decide on an upper, so many flavors so little coin.

[ipijohn]

I tried Eco100 AC oil as a BCG lube - I like it. Not a lot of rounds for testing but it says on and is not messy like mobil1 or lith grease. Applied with a Qtip to the rail wear points. Inside of receiver is dry now, don't see an accumulation of dirt/residue. Doesn't blow crud into the buffer tube either.

I have been using Dupont Multi-use Teflon Lubricant (both spray and liquid) for several years, it goes on wet and the solvent evaporates leaving the teflon which works it's way into the pores and machining marks on the metal.

[MT Chambers]

As a cartridge for ARs it is a good choice, in a boltgun it is not optimal, it is far eclipsed by the .30 Br. in accuracy, with both j-word and cast bullets. I play with both cals. a lot in very accurate rifles and the Br. beats it every time out.