[Laser Sailor]

I'm going to build an AR, this will be a SHTF/HD rifle as well as hopefully something that's just fun to shoot.

I know the difference between 5.56 and .223 and I would go with a 556 chambering if I use the smaller caliber round.

What I'm curious about it building an AR chambered in something bigger, like .308 (which is also 7.62x51 right?).

Would I have to find a special lower or can I use one marked "multi" and build/buy a .308 upper?

Also if I went that way could I build/buy another upper chambered in 5.56 and simply swap them out on a whim? What about .22lr?

I know the 5.56 is a decent cartridge, but if I'm going to use it as a man/zombie stopper I'd prefer a bigger round. What do y'all think?

 

[HotGuns]

Negative.

The .308 uses a longer lower receiver,a longer magazine and a larger bolt head.

They are not interchangeable.

 

[Laser Sailor]

I kinda thought my idea might be too good/simple to be true.

Oh well, no need to debate the merits of 5.56 vs .308

Thanks for the quick answer!

 

[HotGuns]

One thing about the AR that makes is so cool...

Any caliber top half can be used as long as the bolt head is the same size as the 223, or the round fits in the standard mag.

There are several different calibers that fit this criteria.

Also, with a few parts changed out of the lower and a caliber specific bolt, most pistol cartridges can work, the most common being the 9MM and the .45 ACP. The only thing that needs to-be done with the receiver is a magazine block that takes up the additional space.

The .308 is a whole different game. Several hard hitting calibers can be had due to the longer case...its pretty much the same thing as the .223. With the 308 length lower you can get into some serious firepower.

You just have to know the limitations of each platform.

 

[BAC]

Oooh. HotGuns just reminded me (indirectly) of an experiment I had forgotten to write down involving an AR-10, the 7mm-08, the 162 gr A-Max, possibly the 150 gr tipped TSX, and more money than I currently have to spend. I need another job. :rofl:


-B

 

[JohnHenry]

You might look at some of the heavier rounds, like the 6.8 SPC and the recent 30 Remington AR. I haven't shot either, but the specs are nice, and they fit the smaller AR receiver.

Of course, I spoke with a close friend who just came back from some...er, exploits in Afghanistan, and he was using an H&K in 556 (he's usually a sniper). He said the round did its job just fine on actual targets, and was impressed (and he's a bigger bore guy all the time).

 

[Frogbones]

How 'bout build for the 6.8spc round....I find that round is available more than one thinks. Good round to boot!!!

My next rifle will be that cal.


Though...magazines aren't as prolific.

 

[nedrgr21]

Check out the 6.5 Grendel as well - fits on the .223 size lower.

 

[HotGuns]

Oooh. HotGuns just reminded me (indirectly) of an experiment I had forgotten to write down involving an AR-10, the 7mm-08, the 162 gr A-Max, possibly the 150 gr tipped TSX, and more money than I currently have to spend. I need another job. :rofl:


-B

Tell us about that. I see no reason why it couldnt work. I dont really see an advantage over the .308 though, excepy recoil will be almost no existant.

 

[Siafu]

I am a big fan of the AR's modularity. I am looking forward to when Spikes Tactical introduces their new .308 lower in the next few months. I have purchased several rifles from them and the last time I spoke with Tom I was told I wouldn't be waiting too much longer for the .308 milled lowers they have been promising. Spikes has Seekins Precision in Idaho doing their milled lowers and milled uppers and they are just works of CNC art.

If you are interested in other AR calibers I have them in 9mm, 5.56 and .22 and they are all a blast to shoot! :bier:

The .22

The 5.56 and the 9mm

My GF told me to stop calling Spikes and building rifles or she's going to use one on me!

 

[BAC]

Tell us about that. I see no reason why it couldnt work. I dont really see an advantage over the .308 though, excepy recoil will be almost no existant.

This, plus the high BC bullets and only requiring a new barrel is pretty much it for me. :bier:

Mainly what I want is an easy-shooting, longer-ranged rifle in a caliber that won't beat up new/young shooters. An AR-10 carbine in 7mm-08 seems like it should work nicely. Another perk is that Magpul's now selling inexpensive, reliable .308 mags. Problem is I don't have is a .308 AR mag and 7mm bullets to see if the A-max, TTSX, or other VLD bullets would actually fit (lookin' for 2.820" max OAL...).

Anywho, just thinking out loud.


-B

 

[tangoseal]

You want a .308 go and buy a Armalite AR10. They are awesome.

 

[sgb]

If you want to be able to afford to shoot it stick with 5.56.

 

[nutz4utwo]

I think a first AR should be 5.56. There is elegance in the original AR design and I think many shooters are too quick to dismiss it.

With a normal 5.56 upper and lower, a benefit (as you have pointed out) is you can swap out the bolt and mag and shoot .22lr out of it. (a conversion is $225 and a dedicated .22lr upper is more like $500) See my review:

http://www.defensivecarry.com/vbull...2353-review-cmmg-22lr-conversion-ar-15-a.html

It is not the most ultra accurate precision unstoppable conversion, but it is highly functional, great for practice and training, and cheap to shoot!

As of today, I would buy a CMMG "Bargin bin" rifle, a half dozen pmags, and a .22lr conv bolt...

http://cmmginc.secure-mall.com/shop/?cart=2084734&cat=161&

If you want to upgrade to something fancy and more expensive, it would be pretty easy to sell.

 

[nedrgr21]

This, plus the high BC bullets and only requiring a new barrel is pretty much it for me. :bier:

Mainly what I want is an easy-shooting, longer-ranged rifle in a caliber that won't beat up new/young shooters.

I'll repeat my suggestion for the Grendel - very easy shooting, in the same lighter/smaller rifle as .223, and it's longer range ballistics rival the .308. Can ya tell I really want one?:wave:

 

[BAC]

Heh. The 6.5 Grendel is a great round for what it is, but it's nothing that can really compete with platforms allowing longer cartridges than will fit in the AR15. 6.5mm bullets with the Grendel's case capacity really cannot compete with 7mm bullets or better-than-M80 7.62N loads at long range.


-B

 

[nedrgr21]

Not according to these guys - better BC's make up for smaller case capacity. The Grendel with a 123gr bullet and 24" barrel at 1000 yds is only about 70 ft-lbs behind the 168 gr .308 (using grendelballistics.pdf and remington shoot software). I was also thinking of the younger/smaller shooters you mentioned not having deal with more recoil and muzzle blast nor wrestle with the AR10's bulk/weight. Just doesn't seem like the 308 is gonna do anything the 6.5 won't.

 

[Cuda66]

This, plus the high BC bullets and only requiring a new barrel is pretty much it for me. :bier:

Mainly what I want is an easy-shooting, longer-ranged rifle in a caliber that won't beat up new/young shooters. An AR-10 carbine in 7mm-08 seems like it should work nicely. Another perk is that Magpul's now selling inexpensive, reliable .308 mags. Problem is I don't have is a .308 AR mag and 7mm bullets to see if the A-max, TTSX, or other VLD bullets would actually fit (lookin' for 2.820" max OAL...).

Anywho, just thinking out loud.


-B

7mm-08 would be cool...but DPMS already makes an upper in .260 Rem...and it is a serious long-range contender. Bucks about as hard as a .223 AR, as well...

 

[HotGuns]

The .260 is a fine round no doubt.

I shot one awhile back at the range that a guy had in a Remington 700 that he had rebarreled.

Although it was accurate and it looks good, I couldnt help but wonder what it does that other rounds dont do. It seems like an answer to a question that nobody asked.

 

[BAC]

nedrgr21, with all due respect to Bill Alexander, those are very optimistic velocities and energies. Those charts impressed the hell out of me at first, but it doesn't seem like anybody's been able to reproduce them. Just sayin'.

Cuda, the .260 is definitely also an option for an AR10. I'll probably be trying it, or one of its relatives, too. If you note the wording of my original post in this thread, you'll find the word "experiment" used. :wink:

HotGuns, like most 6.5mm offerings, the .260 Rem is a long-range option for target shooting and mid-range hunting. Carefully loaded you can take any game in North America with a 6.5 provided you're a good shot against the larger bear and elk. When you consider what you get downrange compared to the .308, for considerably less recoil, the .260 is a nice round. Its popularity is pretty evident given the two cartridges made specifically to compete with it (6.5 Creedmoor and 6.5x47 Lapua).


Merry Christmas Eve. :santaclaus:


-B