Does anyone do this with AR platform?

[gregorio]

I understand the AR platform can be adapted to different calibers mostly with an upper change. Does anyone swap uppers to .308 or 458 or are lowers cheap enough that you just build complete guns in different calibers?

I'm asking because I'd like to have a variety of calibers and maybe even a .12ga based on the AR platform. The reason is weapon familiarity and standardization. I like my AK but not quite as much as the AR (M&P)especially with the price of ammo and parts being cheaper. Switching between the two is like driving a right hand automobile after learning on a left. Everything seems to take longer for my brain to react.

Last, what calibers and manufacturers do you like for plinking, long range (3-500yds) target practice, defense?

[pratchett]

Someone correct me if I'm wrong - I frequently am - but here is the information I think will answer your question:

1) The AR-15 magazine well will not accommodate the .308 Winchester. You can feed the cartridge manually into the chamber, and I believe there is a .308 Winchester upper designed as a single-pull.

2) There are .30-caliber upper receivers, but not for the .308 Winchester round.

3) The 12 Gauge suffers from the same problem: it won't fit and/or feed from the magazine well. There are 2 (or more?) AR-pattern shotguns in 12 Gauge, though.

4) As far as calibers and manufacturers, Calguns is a wealth of information, and I'd suggest you do some research by using the search function. Alternately, you could go to Google and type in "site:calguns.net," press the space key one time, and then entering your search terms.

[unusedusername]

Pratchett you are correct.

Neither a .308 Winchester nor a 12Guage magazine would fit into the magazine well of an AR-15. Those rounds are too big for the magazine well.

An AR-10 will accommodate a .308 Winchester as it was designed for 7.62x51 in the first place, and that round is just a .308 with a tiny bit less powder. A 12 gauge still won't fit even in an AR-10.

Other calibers, including 6.8, and .50 Beowulf will fit in an AR-15 though, and you can have multiple uppers and swap them out at will without any issues.

Of course, the upper and the optics is nearly the entire cost of the rifle, so having a single lower does not save very much money.

[WARDOG]

It depends on what special magic you have in your lower.
I have several AR-10's, but one lower is pecifically designated for multi cal upper receiver switches. It has a Knights Armament trigger, special pistol grip, and a custominzed PRS stock.
It is a Registered Assault Weapon through DOJ, so I can use any magazine capacity I want.
That lower uses uppers in .300 Remington Short Action Ultra Mag 28" bbl
, .308 carbine 16" bbl, .308 rifle 24" bbl, & .243 22" bbl for 'yotes. I can't afford to build up 3 more lowers with the same expensive components.

[bohoki]

generally if the cartridge will fit in a magzine that fits in the lower an upper has probably been made

[USACracer]

My buddy has the .50Beo and it's sweet to be able to go from 223 to 50 cal in 1 minute.
There are 7.62x39, 9mm, .22 uppers that all swap on, just make sure you have the right mag and ammo for the upper(s) you will be using that day.

One thing that drew me to the platform was the "mr. potato head" ability.

[Full Clip]

Yep, two lowers - one with target trigger - and five uppers here. Modularity is part of what makes the AR awesome.

[gregorio]

Thanks everyone. That is exactly what I'm thinking. Take one lower and build the crap out of it and another for kicking around. Then, have a variety of uppers to swap in and out as I want. Optics can be swapped too.

Now comes the obvious follow up questions 1) what is the best lower to use for this and 2) what are the calibers of uppers out there that are available?

I'm leaning towards machining my own from 80% blocks and so far find that .223 and .458 are the two calibers that are coming up in searches.

[Full Clip]

I'm not crazy rich, so I just bought a couple stripped Stag lowers back when. Nothing fancy, work fine. The best uppers for you may be different than for someone else. I went with 5.56, 7.62x39, 9mm, .22LR and .50 Beowulf. Covers a lot of bases, from cheap plinking to the sledge ...