Ideally I want a do it all caliber

There is no do it all caliber. Pick your main goal and what is secondary. Then we might be able to give you some help.

 

Why not get a platform that can do both easily?

My LMT can change caliber with a simple barrel swap:

 

Re: do it all....

For one size fits all, bigger is generally a lot better.

Having said that, 5.56 and .300 Blackout are mouse guns as far as hunting rifles go.

 

300 BLK with supersonic ammo will take common North American game.

 

If you are considering hunting, then 300BLK should cover most places for hunting just about anything. Otherwise, just for plinking and target shooting, generally 556 is more available and cheaper.

After you choose, wait for sales on the other calibers' upper then get that one and have both JUST be REALLY careful to MARK uppers AND mags of both 556 and 300BLK so you don't shoot mismatched ammo. The 556 and BLK are designed to fit into same mags and will look like they chambered, but mismatch (especially 300BLK into 556 barrel) will end badly.

 

not all game is big game, guys. The 22lr conversion unit for the 223 will take small game, train novices, is permitted at indoor ranges, saves you 50c per shot, wont blow out your barrel in 5-10k rds. That versatility makes the .300 look sick by comparison. You can always have a spare upper receive in .458 SOCOm, which will take deer to 400m with a silencer and subsonic ammo. Much better than 300. The .458 subsonic doesn't need brain hits to silence a sentry, but the 300 BO does.

https://www.youtube.com/results?search_query=subsonic+458+Socom+subsonic+on+deer+at+400m

 

.300blk either isn't reliable, or needs special mags, buffer spring, etc.

Won't be building another one.

Short barreled AR's aren't anything I'm going to build anymore either. Prefer 18" rifle.

 

For clarification:

In my experience, unless you go subsonic, all supersonic 300BLK loadings I've shot using standard buffer weights and springs shot and cycled just fine. HOWEVER, If you do subsonic/suppressed, then yes, tweaking may well be needed including buffer springs, weights, and variable gas settings to get reliable AR cycling.

Mags: Again, subsonic ammo MAY not feed well in 556 due to cartridge length and bullet ogive. Supersonic 300BLK loadings are much less likely to misfeed.

 

I’m currently searching for parts to put together a rifle. My biggest decision at the moment is caliber. Ideally I want a do it all caliber but will most likely end up with other calibers down the road. For now I just need a do all option.

I’m down to 5.56 and 300 blackout. Minus ammo cost there really isn’t much of a difference for me since I don’t live in a free state. I won’t ever be able to suppress anything, I’m limited to 10 rounds regardless, etc. the only pro each has that applies (from what I can see) is 5.56 being cheaper and 300 being a better hunting cartridge.

In general is there really going to be much difference if you can’t suppress the 300? If I could it would be a no brainer.

The normal primary draw to considering a 300Blk is for suppression. The next reason is to be able to shoot both supers and subs out of the same platform albeit you need to reset or take into account different zero’s.
A 556 / 223 chambered AR platform is the predominant all - around rifle.

300 Blk also costs 50% to 100%!more to shoot than 556. I see you have considered that but it is one thing to think about it and another to actually have to spend an extra $100+ every time you go to the range,

What is complicating your decision is the hunting aspect. If it was me I would buy an AR in 556 and a specific scoped bolt action rifle for hunting…… particularly as suppressors are off the table for you. (Suppression is 40%, if not more of the reason people get 300 Blk)
YMMV

 

As stated by others, a lot depends on your primary use. What state are you in? What is a likely hunting scenario? If you're hunting thick wooded areas, from a tree stand or blind, with shots being limited in range, a 300BLK would be perfect.

For those of us out west, a 300 BLK will certainly work, but far less than ideal. IF you're planning on using it for general shooting, and the occasional hunting trip. I'd go with a 556/223, for ammo availability and cost to be sure. IT can be used for hunting, although I'd take the 300BLK over the 556 for deer sized game in most instances.

 

I've got 5.56 but wish I'd started with 300 blkout. It seems that the 5.56/.223 became the defacto AR round in the US military because one could carry a lot of rounds. But the .300 blackout comes in sub and supersonic loads. I haven't gotten a .300 upper yet, largely because I'm in a state that has pretty much banned everything, so I'm waiting for the legislation to be struck down in the court. Hopefully later this year. I think it all depends on what you want to do with it.

 

5.56 would be my first choice...personally would go 6.8 SPC or 6.5 Grendel if I was stepping up from the 5.56, both are better for hunting than the .300 BLK.

 

do 5.56 first
if you want to explore SBRs and suppressed shooting get the 30BO later.

6.8 and 6.5 are niche cartridges that are better for longer range lethality (think hunting)

 

do 5.56 first
if you want to explore SBRs and suppressed shooting get the 30BO later.

6.8 and 6.5 are niche cartridges that are better for longer range lethality (think hunting)

SBR’s will not be a thing due to the non free state I live in.

 

I live in NY, Upstate, 60 miles from Canada, not NYC. I went down the AR rabbit hole a few years back. Here we can have short barrel guns with pistol brace as long as on your pistol permit. Still 10 rounds though.
I really like my BCM 10.5 300BO gun.
It's my HD gun, like mentioned the ammo choices vary greatly, but the 115 grain supersonics are a nasty little round. My local range is only out to 200 yards, so it works just fine, I haven't hunted in years, but I have a coworker that's said if I ever want to hunt his land I know it will take a deer and shots are rarely further than 200 in NY. And it hits a little harder and has better soft cover penetration if that needs were to ever arise.
In all Im happy with the gun.
I do have 3 AR's in 556, a 12.5, 14.5, and 16. I've never put a round through any of them. Just built them a few years back and they sit in the safe with 1000 rounds of green tips, I've been meaning to dig them out one day, but really don't see the need as I usually just plink 2-3 times a year.

 

I’m in Ny as well and wasn’t aware we could do SBR’s. I’m in the finger lakes region. Good to know I can add an sbr to my permit.

 

Do all is a fallacy. Personally I’d chamber it in 556 and call it day. If you need something else. Then get it

 

I think it boils down to what you are going to use your rifle for and what barrel length you are going with.
Without a suppressor my 9" 556 is basically a novelty. Way too loud and way too much muzzle blast to be practical for anything but annoying others around me. 300blk is way more practical. As others have stated, 300blk is way more versatile than 5.56 as well. I wouldn't want to be shot by either caliber, but 300blk is the superior defense round.
I have the same rifle as nikerret with the standard 5.56 barrel and an 11" 300 barrel. I've never even used the 5.56 barrel. But I also have other 5.56 rifles.
Again, like others have said, 5.56 has it all over 300 for ammo cost and ammo availability. If you are using it for plinking then 5.56 is the way to go. Since you can't get a suppressor they are both equally fun to shoot out of standard length unsuppressed rifles.

 

As someone else said 6.8 SPC, 6.5 Grendel are options. Even 6mm ARC is an option whether you go short barrel or not, if 556 is considered too diminutive. My 10.5” Grendel and ARC AR is one of my favorites.

 

If I was starting new, it would be 300.

 

Since you do live in a communist state and the pistol brace rule remains unsettled, maybe you should consider 5.56 vs .308.

.308 is a versatile round and lots of fun in the AR platform. Probably overkill for short / medium distance target shooting and ammo is considerably more $$ that 5.56, but that round pretty much can do it all if you are shooting under 800 yards.

I have a .300 BLK SBR, great round for that application, but IMO not as much so in a long rifle.

 

If you are not shooting suppressed I would not get into the Blackout. I would get the 556 and pick up a 6.5 Grendel upper for hunting if you were looking to hunt with the AR platform. The Grendel is a very good medium game hunting round. I have all three rounds, BO for suppressed shooting, Grendel for Hunting, 556 for plinking/stockpiling ammo.

 

I would start your build with a 5.56mm upper. I’ve been experimenting with heavier bullets when they go on sale like the Palmetto State Armory 75 and 77 grain AAC and they are pretty accurate out of a 18” barrel. For me, 5.56mm is a fun and economical round to shoot.

 

Supersonic .300 BLK is essentially 7.62x39.

I have two 6.8 SPC uppers - one 20", the other a 16" lightweight. 6.8 is a great general purpose hunting cartridge.

I also have an upper in .25-45 Sharps, which is a 5.56 case necked up to .25 caliber. Loaded with 87gr Speer Hot Cor softpoint, it's accurate, effective, and legal for deer.

But...

If I were to do it all over again today, I'd probably choose 6mm ARC. I'd do an identical 5.56 upper setup to practice with and a 6mm ARC upper to hunt with.

 

I'm in the same boat with Grendel. If I were to do it all over again I'd forgo Grendel for ARC. Which is what I am slowly doing now.

 

I live in a similar state, I have a Flightlite, SCR, and 223 and also bought a 350 legend, upper from Bear Creek Arsenal. 350 legends is your do all cartridge.

 

I’m currently searching for parts to put together a rifle. My biggest decision at the moment is caliber. Ideally I want a do it all caliber but will most likely end up with other calibers down the road. For now I just need a do all option.

I’m down to 5.56 and 300 blackout. Minus ammo cost there really isn’t much of a difference for me since I don’t live in a free state. I won’t ever be able to suppress anything, I’m limited to 10 rounds regardless, etc. the only pro each has that applies (from what I can see) is 5.56 being cheaper and 300 being a better hunting cartridge.

In general is there really going to be much difference if you can’t suppress the 300? If I could it would be a no brainer.

Browse Bear Creak Arsenal to check out their offerings so that you k ow what's available and possible with an AR15 lower.
You could also consider the AR10 platform for bigger cartridges.

 

14.5 or less.

No more. Just don't have the purpose of a rifle.

 

First one, then the other?

 

I'm only considering 300 for suppressed home defense. 5.56 is so much more economical. I've got way too many AR's as it is, another suppressor host upper is just waiting in the wings.

 

5.56 no question