Anyone Want to School a Newb on 300Blk?

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Tophernj

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I never thought I'd be saying it, but I am...

...I'm building an AR. In 300 AAC Blackout.

Aside from the fact that they are (to me) pretty ugly they are quite fun to shoot and reasonably accurate. So, I'm going to go for it. I am going the full on build route. Stripped lower and upper, both forged Mega Arms. I will be picking up the LPK from Midwest PX as he supports a "local" forum that I inhabit. Hella nice guy as well. I'm currently un-decided on the trigger but am considering a Geissele SD-C as I am a fan of flat triggers. I run them on my 1911 and find them to be very comfortable. (Any trigger suggestions are welcome.) ACE Skeleton stock. For the most part, the lower is pretty set.

It's the upper that I'm worried about. BCG will most likely be a Midwest PX unit as well for the above stated reasons. My questions come in regarding barrel choice. I would like a 16". I am not sure what to look for in twist rate. I am not allowed to own a can or an SBR. Supersonic is my only (real) option. I am thinking that a 1/8 would be a bit better for me but is something a bit slower more desirable? Gun will be used for range/plinking and a pig hunt(hopefully) later next year.

Also, a quick primer on gas tube lengths and their pros and cons would be most helpful.

Thanks all.

Christopher
 
I'm not a pro on 300BLK, but I have done some reading so I'll share a few things I know.

300BLK will only run on Carbine length or shorter gas system, so that means carbine or pistol length gas only. It will not cycle reliably in a midlength according to Rsilvers. (correct me if I'm wrong). If you are getting a standard 16" barrel, then go with a Carbine length gas. If shorter than 16" (under 10", Pistol AR) then pistol length gas tube/block.

1:8 is the ideal barrel twist so you should stick with that. Most 300BLK barrels are 16" anyway. I would suggest buying a barrel from AAC or CMMG, although there are others that produce them.

Read up on other threads regarding the caliber. I'm sure others will chime in later on. Good luck with the build.
 
You may be best suited to clearly define your purpose for the gun

There is a ton of mis information on the 300blk that I can see.

Some people make it out to be a do all cartridge - it isnt

Some people make it out to be a dog cartridge - it isnt
 
I've got a 300 BLK and really enjoy it. Although the round was benchmarked against 7.62x39, I find it closer to 30-30 in performance.

There are only two gas system lengths that I know of - Carbine length and pistol length. 300 BLK reaches powder burnout at 8 inches or so, which makes it an ideal choice for SBRs. The round also excels as a subsonic load, making it great for suppressors. IMO a carbine length gas tube offers the best flexibility for both lighter supersonic and heavier subsonic loads. A pistol length gas system limits you to heavier bullets.

If your state doesn't allow SBRs and Suppressors, or you don't want to wait the 9 months or so that BATFE takes to approve them, look for a 14.5 - 16" barrel with a carbine length gas tube. If you go with a barrel shorter than 16", you'll need use a muzzle device long enough to make up the difference; the muzzle device will then need to be permanently attached to the barrel through pins or welding. EDIT: I just saw that you're in NJ. You probably know this already.

In SW Oklahoma, we have a HUGE pig problem and the 300 BLK really excels as a pig killer. You have the light weight of a 5.56 AR, making it easy to carry and handle, with the terminal effects of a 30 caliber bullet. 300 BLK makes pig hunting easier, IMO.

I'd also feel comfortable hunting deer with it in areas where the density of vegetation and terrain limit the max distance of the shot to 100 yards or less.

If you don't reload, I'd consider starting if you get a 300 BLK. Finding ammo can be a bit of a challenge.
 
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Thank you LebbenB. I appreciate the input. Especially the clarification on gas system length.

Yup, I know the laws in NJ well having navigated them for a while.

As to the ammo, a large part of why I'm interested in 300 is because of it. I do reload and will be forming my own brass. 308 bullets are pretty plentiful and 223 brass is even more so. I have gotten some powder and will be ready to roll. The idea of "making" my own brass is very appealing to me. I like tinkering with ammo almost as much as I like dispensing it down range.

C
 
Not to turn this into a reloading thread, but I mainly use Lil Gun and H110 for 300 BLK and have gotten good results from both.

300BLKTalk is a niche forum for the caliber and it has a pretty comprehensive list of recipes and loads.
 
I built a .300 Blackout this year. I'm using the Harbor Freight cutoff saw for cutting the brass down. Right now, I'm using 1680, but also have some 2200 and AA#9, both of which there is .300 Blackout load data.

I recently loaded a batch of 168gr. hpbt bullets @ just under 2000 fps. I believe that's plenty of energy for taking deer out to 150-200 yds. Most deer in my area are taken at under 100 yds.

I will be shooting suppressed, and I won't be hunting with my .300 Blackout, unless I decide to dispatch some pigs.
 
Are you a reloader? Bullet caster? I love the 300blk for shooting cast from the AR platform. Accuracy is good and you can't beat the price of bullets poured at home.
 
Great info so far. I'll tag this for reference as well. I plan to get a .300blk barrel/maybe upper for my AR, once I get an AR that is. I'll narrow a question based on some info so far: someone stated the powder of this round usually being burnt up within 8" or so. I know you can't have an SBR in NJ but what about an AR pistol build, possibly with one of those new 'AR pistol arm braces'? If there is no significan performance loss in a 10" vs 16" barrel for the .300blk, and an AR pistol is legal in NJ (I don't know if it is) would this better suit your needs and make this platform more significantly different from your other firearms?
 
There are some guys doing cast for 300 that are showing some good accuracy.

Since you reload, you get the maximum benefits from the bullet.....

But...... Its NOT a 150 to 200 yard hunting round

Inside of 150 it should take pigs all day. Some of the people in Texas here are using them
 
for anything besides suppression i have doubts the .300 AAC blackout has the velocity to really expand or utilize those 300 caliber bullets, nor will it have much for range and will drop like a rock, and it is a far cry from .30-30 and 7.62x39mm
If you look at the heavy subsonic loads in isolation, you're correct - 220s run out of steam at 150 yds or so.

But when you look at loads comparable to 7.62x39, say a 125/135 gr supersonic load, 300BLK compares very favorably to 7.62x39 and 30-30. But I think you knew that already;)
 
I'll just jump in and do my normal babbling.

The .300 AAC Blackout is in its own world. It doesn't replace any one other caliber.

To your questions and concerns. The Blackout is gas hungry, so a carbine gas system (or pistol if you go that way) is your best bet. Barrel lengths longer than 16 inches is a waste, little if any gain in velocities. Twist of 1 in 7 or 1 in 8 will do fine.

The BlackOut shines at both ends of the bullet weight curve. Light/er bullets at reasonable high velocities, heavy weights lumbering along at just below the speed of sound. And in the middle, surplus GI bullets are great fun.

The BlackOut is more for the re-loader (currently). Preferred powders are the same as those for heavy magnum pistols. Primers, well 296 should have Mag pistol primers but does quite well with standard small rifle primers. Brass is reprocessed .223/5.56. (I have only used my 'throw-a-way' scrap brass so far. 16 and more reloads with recycled .223/5.56 brass that had been tossed into the scrap box isn't a bad brass life.) And bullets, seating depth (this makes greater pressure changes than I expected in the BlackOut) to have ease of chambering is about the only thing to watch for.

And beauty is in the eye of the beholder. And ugly is as ugly does.

For those who don't like the AR/M4 or the BlackOut. Your privilege. I do. Great fun.
 
Don't worry about the twist. 1/7 has become the standard but it came out with 1/8. Just because you will be using supersonic only is no concern
 
I briefly owned a Savage prefit McGowen 1:8 16.5" 300 AAC barrel.

It was a fun toy with 220 subs, even unsuppressed...but that's about it. I sold the barrel as 5.56/77gr was far more suited to my intended uses for intermediate range work for minimum expense.

That said, I do think it is a good whitetail cartridge for <150yd shots, especially for recoil sensitive shooters, depending on the bullet used (Barnes and 110 Vmax have lower expansion velocities). Also, I've seen 208 Amax subsonic ballistic testing and it looks like a very viable subsonic hunting bullet.
 
If you're gonna shoot supersonic only with a 16" barrel go with a 1 in 8" and a carbine length gas system.
I got my barrel from Alpha Shooting Sports they usually have melonited barrels for a good price.
 

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Any reason you'd consider the 300blk out over a 6.8spcll or a 6x6.8 or even a 6x45? 6x45 is going to be my next Ar build I complete. 6mm bullets are plentiful, 223-556 brass you covered. Hardly any recoil and they will whack a deer farther than >100 yards. If your set I'm not trying to change your mind. I've considered a blackout simply because I already have a 30cal can but if I could ony run supersonic or reduced I'd look at a 6x45. Jmho
 
The 300 BO is what it is, it's it own cartridge brought out mainly for shooting suppressed heavy subs, it will never be a 30-30 Win, 7.62 x39, a 30-06 or a 300RUM for that matter.

You fans of the 30-30 try installing a suppressor on your granddad's thurty thurrddy and shoot some 240gr Sierra MK's at around 1000fps through it and let me know how that works out.:p
 
Since the thread drift was getting out of control I've now deleted all of the posts, including my own, comparing .300 BLK, 7.62x39, and .30-30 Win. The OP is building an AR-15 pattern rifle in .300 BLK. Help him with that or keep or your peace.
 
Since the thread drift was getting out of control I've now deleted all of the posts, including my own, comparing .300 BLK, 7.62x39, and .30-30 Win. The OP is building an AR-15 pattern rifle in .300 BLK. Help him with that or keep or your peace.
That's a little sad as I gained a bunch of info from the rantings of others. Oh well.

Anyway, yes, I'm building an AR pattern rifle in 300blk. Reasons are several. I'm looking for something different than the normal .223/5.56. However, I like that it's only a barrel change, essentially. Meaning, if I decide to switch back to the normal AR cartridge, I'll just need to put a barrel on and I'll be gtg. Also, I like that 300 is a reloaders cartridge. I will be forming my own cases out of 223 brass from a friend. Other cartridges that I looked at things weren't that simple. The availability of spare 223 brass and 308 bullets is very appealing. I'm also a fan of heavy bullets moving kinda slow when it comes to the house and it's defense. I know I'll probably get slammed for this but the 300blk reminds me of a .45acp in a rifle cartridge. Meaning a big'ol bullet moving slowly but with enough snot to settle someone down pretty quickly. I like it. I am also looking to do a pig hunt sometime next year and this should be a great cartridge for that.

Again, in my state, suppressors and SBR's are out. Pistols are pretty impractical. I know that. I also know that the 300 is NOT the be all-end all cartridge. I know what it is and for the most part what it isn't. It's an oddball that I'm looking to take a chance on.

C
 
Dean1818 said:
Quote:
Originally Posted by dubbleA View Post
The 300 BO is what it is, it's it own cartridge brought out mainly for shooting suppressed heavy subs, it will never be a 30-30 Win, 7.62 x39, a 30-06 or a 300RUM for that matter.

You fans of the 30-30 try installing a suppressor on your granddad's thurty thurrddy and shoot some 240gr Sierra MK's at around 1000fps through it and let me know how that works out.
_______________________________________________________________
You are 100% missing the point

The whole problem is the many highly innaccurate statements made by people for comparisons sake in regards to the 300blk

Sell the 300blk for what it truly is....... There are many benefits

No reason to compare crap bullets from other chambers to the best bullet the 300blk offers
__________________



How am I missing the point? I understand what the 300 BO's purpose is for and use it as that plain and simple. My last quote is just referring to the BO being able do perform something the 30-30 can not, not a big deal.

I could care less if folks claim to get 30-30 ballistics from the much smaller case of the AAC Blackout. It doesn't take a nuclear scientist to figure out that more case capacity will equate into more velocity in a given caliber and a given weight. It's really that simple. Certainly not going to appoint myself a cyber cop on internet boards and argue the point.

What I will do in a couple of weeks is to cull some does with some heavy weight sub sonics from a suppressed 300 BO and maybe post a video or 2. It shines doing that, after all that's what is was designed for. It wasn't brought out to duplicate the Russian round, the thurdaa thurdyy or a 12 ga slug gun.
 
That's a little sad as I gained a bunch of info from the rantings of others. Oh well.

Anyway, yes, I'm building an AR pattern rifle in 300blk. Reasons are several. I'm looking for something different than the normal .223/5.56. However, I like that it's only a barrel change, essentially. Meaning, if I decide to switch back to the normal AR cartridge, I'll just need to put a barrel on and I'll be gtg. Also, I like that 300 is a reloaders cartridge. I will be forming my own cases out of 223 brass from a friend. Other cartridges that I looked at things weren't that simple. The availability of spare 223 brass and 308 bullets is very appealing. I'm also a fan of heavy bullets moving kinda slow when it comes to the house and it's defense. I know I'll probably get slammed for this but the 300blk reminds me of a .45acp in a rifle cartridge. Meaning a big'ol bullet moving slowly but with enough snot to settle someone down pretty quickly. I like it. I am also looking to do a pig hunt sometime next year and this should be a great cartridge for that.

Again, in my state, suppressors and SBR's are out. Pistols are pretty impractical. I know that. I also know that the 300 is NOT the be all-end all cartridge. I know what it is and for the most part what it isn't. It's an oddball that I'm looking to take a chance on.

C
i used to really like the 6.8SPC but for reasons like you stated i abandoned it because the base/rim diameter was a bit of an odd size making finding donor brass a bit more difficult for making my own.. it could only use really short, low BC bullets anyway.. so thats one thing ill give the .300AAC blackout is lets say tomorrow, everyone stopped making .300AAC blackout ammo you could simply reshape some of your .223 brass and add a 30 caliber bullet, both components pretty cheap and common and never have to worry

and i just COMPLETELY contradicted myself as i love 5.45, and thats even more difficult to reload for than 6.8
 
I'm debating doing a .300 blackout build at the moment. It's nice because it's just super easy....just change the barrel. Same bolt, same mags, brass can be made easy from .223..bullet selection is great. I mean...there's a LOT to like about it. I could literally buy a barrel and a set of dies and be all setup for a different caliber just like that. The only thing that I'm debating is that I don't really need it for any one purpose at the moment. I suppose hunting purposes maybe I could use it where I wouldn't use a .223. I still want to build one so I probably will end up building one. Sometimes you don't really need a reason other than wanting something new to try.
 
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