Why not?

[jguilletjr]

It seems like since the gun Mfg. Make a conversion for the AR to a .22 cal, Why not make a magazine that would fit in the .308 receiver that would convert it to a .223 / 5.56? Then you could use your .223 upper on the same lower as your .308 / 7.62. That would be a really versatile system I think.

 

[DAVE_M]

It seems like since the gun Mfg. Make a conversion for the AR to a .22 cal, Why not make a magazine that would fit in the .308 receiver that would convert it to a .223 / 5.56? Then you could use your .223 upper on the same lower as your .308 / 7.62. That would be a really versatile system I think.

Why not? That seems awfully useless.

If you have a .223/5.56 upper, you probably have a .223/5.56 lower, so why wouldn't you just use those?

 

[SpeedRacer]

They're also not cross-compatible. That means you'd need a proprietary 5.56 upper (among other parts) to go with the proprietary mags. With the current price of ARs, you'd probably spend half as much just buying a separate 5.56 gun with cheap mags aplenty.

 

[Doctor481]

I think it could be done, but the small market segment would make the cost unbearable for what you get.
I have one of the CMMG .22 conversation kits, it works fine. Seems like it was about $180.
I'm now wanting to build a .22 dedicated upper, using the CMMG bolt assembly.
For an upper, barrel, handguards and the miscellaneous parts I'm around $450.
To get the project shooting I'm pushing almost $650.
I could just buy a .22 caliber AR or 2 Ruger 10-22's for that amount.

 

[Magdump]

Are we talking about pinning a 5.56 upper to a .308 lower? They are not built to fit together is why not. Regardless of magwell size, the deminsions of the receivers are different.
I think that's what the OP is asking. Nothing major compatible between the "AR 10" "LR-08" or any other 7.62x51 AR style rifle and the AR 15. Although they share the same design, the difference in case size called for differences in receiver dimensions and the size of other parts.

 

[noob]

It's been done before and colt currently makes the kit

http://www.impactguns.com/colt-308-ar10-le901-16s-rifle-16in-multi-caliber-308-556223-le901-16s.aspx

Has a Magwell block with a relocated pin that fits their 308 upper and a 556 upper

 

[rcm192]

It's been done before and colt currently makes the kit

http://www.impactguns.com/colt-308-ar10-le901-16s-rifle-16in-multi-caliber-308-556223-le901-16s.aspx

Has a Magwell block with a relocated pin that fits their 308 upper and a 556 upper

And see how expensive the colt setup is! Not bad if thats what youre after though.

Its been done before the colt too....google MGI Hydra.

 

[jguilletjr]

Are we talking about pinning a 5.56 upper to a .308 lower? They are not built to fit together is why not. Regardless of magwell size, the deminsions of the receivers are different.
I think that's what the OP is asking. Nothing major compatible between the "AR 10" "LR-08" or any other 7.62x51 AR style rifle and the AR 15. Although they share the same design, the difference in case size called for differences in receiver dimensions and the size of other parts.

I know it would be difficult with current stuff. Im saying why cant the Manufacturers come up with a one lower receiver system that would do it all, so you don't have to own different weapons. I can convert my .223 lower from a carbine to a long range varmit rifle in a few seconds. you can make it a .22 rimfire just as easy. It would be cool to be able to make it a 308. So if the lower receiver obviously wont work, why cant some one make a set up that would? You guys have no imagination. The way you think, we would all be driving buggies and plowing with mules. It can't be done isn't an option. It hasn't been done yet is all.

 

[SpeedRacer]

Imagination is usually limited by the desire to make a profit.

 

[noob]

Not only that, with what's available now, it doesn't make sense to have a bigger heavier rifle to shoot a 5.56 round. My sig 716 is over 9 lbs before optic, magazine/ammo, etc. would I want a 10lb 556 rifle? nope!. You usually dress for the occasion, just like when shooting, you usually bring what ever is capable for what every sport or game you plan to do. The 5.56 to 22lr and also longer barrel platform swap you speak of is easy since it uses the same diameter projectile, and for the most part about barrel length the same round. The 22lr being a smaller munition, which is easier to adapt.

If 1 gun can do it all, than it would have been done so instead of the 1000's of different guns out there today.

 

[randy13]

Imagination is usually limited by the desire to make a profit.

Yes. because there are a lot of costs to realize the imagination..