AR opinions: 5.56 / .300 / .308 / 6.8?

[04ctd]

mentioned it in the 6.8 thread, thought would ask your guys input.

i want a Ruger piston AR, but the last one i saw for sale was a 6.8...

below is from: http://300aacblackout.com/

DESIGN OBJECTIVES
? Create a reliable compact 30-cal solution for the AR platform
? Utilize existing inventory magazines while retaining their full capacity
? Create the optimal platform for sound and flash suppressed fire
? Create compatible supersonic ammo that matches 7.62x39 ballistics
? Provide the ability to penetrate barriers with high-mass projectiles
? Provide all capabilities in a lightweight, durable, low recoiling package

REASONS 7.62x39 wAS NOT CONSIDERED
Extreme cartridge taper
? Reduces reliability of feeding in AR Magazines
? Reduces Magazine capacity
? Cartridge taper induces considerably higher bolt thrust-
exacerbating the AR Bolt's weaknesses
? Requires a larger Bolt Face which reduces Bolt Locking Lug strength-
exacerbating the AR Bolt's weaknesses
Limited projectile selection
? 0.311" diameter not a common option in most modern bullets

even more info, hit "Control and L" at the same time to make it full page:
http://300aacblackout.com/resources/300-BLK.pdf

 

[04ctd]

http://www.thehighroad.org/archive/inde ... 25866.html

few good synopsis on there:
-AR-15 is lighter.
-AR-10 reaches out further, hits harder, weighs more

AR-15 = fun plinker, good apocalypse gun (more common ammo)
AR-10 = long range hunter, weighs too much, cost more to plink.

so buy a 5.56 first, then a .308 or something to round out the collection.

 

[Tigerstripe]

save up for a machine gun, m-16, then add different uppers. i have 223,9mm, and 22

there are pics of me using Clickers 752x39 upper on my auto lower on the fall 2012 shootenzfest pics.

THANKS CLICKER, what kind of bolt is in that upper, has it ever broken?

 

[Clicker]

THANKS CLICKER, what kind of bolt is in that upper, has it ever broken?

You are welcome TS, any time.
It's supposed to be all Colt but I can't really be sure as I bought it from a friend and he purchased it off someone else as well. The bolt is original and no issues so far.

There is alot of buzz around the 6.8 and it's interesting but the special mags and bolt put me off for now. The ammo costs are higher compared to 5.56 as you probably know. I already have a "special needs" upper in the 7.62x39.

I joined the 300 Blackout party and it's been a fun ride so far with no end in sight. I've concentrated on subsonic load development but can see the merits of supers in this platform. My investment was limited to the barrel and a gas block since I had everything else on hand. My objective is to hunt with it and hope to take some large game soon.

If you elect to go with the 6.8 simply buy different uppers later to add 5.56, 300 Blkout etc.

 

[04ctd]

If you elect to go with the 6.8 simply buy different uppers later to add 5.56, 300 Blkout etc.

the problem with this was, if I bought a Ruger to get the Piston system....then you cant change uppers

 

[Parhams0508]

My objective is to hunt with it and hope to take some large game soon.

I thought about that as well, but the 300 BLK burns all of its powder before 16", which kind of worries me about it's long-range effectiveness. Plus, the weight of the bullet would cause some considerable drop at longer ranges (100+ yards).

If I understand its ballistics correctly, that is.

That being said, I think that a 300 BLK upper should be in the hands of every AR owner, just 'cause.

 

[Paco]

My objective is to hunt with it and hope to take some large game soon.

I thought about that as well, but the 300 BLK burns all of its powder before 16", which kind of worries me about it's long-range effectiveness. Plus, the weight of the bullet would cause some considerable drop at longer ranges (100+ yards).

If I understand its ballistics correctly, that is.

That being said, I think that a 300 BLK upper should be in the hands of every AR owner, just 'cause.

That would only be if you were trying to shoot the subsonics out past 100 yds.
The 110~125gr 300BLK with a zero at 200 yds shoots approximately like this:
50yd: 1.5" high
100yd: 3.5" high
200yd: 0"
300yd: 15" low (with over 600 ft-lbs)

For a full look at the table, see page 19 of http://300aacblackout.com/resources/300-BLK.pdf (from 04ctd's original post)

 

[Clicker]

If you elect to go with the 6.8 simply buy different uppers later to add 5.56, 300 Blkout etc.

the problem with this was, if I bought a Ruger to get the Piston system....then you cant change uppers

Help me out on that one, why can't you pin any old upper onto the Ruger lower? I'm pretty sure Ruger sells their upper separately so it must fit standard lowers.
I figured at most you'd have to change the buffer and spring but that any upper would fit.

 

[bigfutz]

I thought as well the Ruger used a standard lower, unlike some others such as the Para TTR where the recoil spring is over the barrel. As you can buy piston uppers for standard lowers (Adams, CMMG, etc) is there a consideration with the buffer tube spring? I obviously know very little about piston uppers

 

[04ctd]

you guys will have to educate me on pistons, i guess.

my point was, if i bought a ruger so the piston system did not blow gas/powder back into the lower,

then swapped on a gas lower, it kinda defeated the point of paying good coin for a piston rifle or upper.

FWIW, a buddy has a PSA lower that he never uses (has a full 20" barrel, and we KNOW those are not tac-tee-cool!)

going the 300BLK might be the route for that gun.

thanks for the reasonable discussion & back & forth.