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Posted: 4/17/2008 5:09:08 PM EDT

I thought I had heard somewhere before that ar 15 were basically a modular rifle that can be interchanged....I guess my question is ..i have an ar15 but was wondering if i wanted to build a new upper that can be interchanged with my complete what would my options be? caliber sizes that would work with my 5.56 complete lower....

thanks

Posted: 4/17/2008 7:37:55 PM EDT

[#1]

AR15's are basically the legos of rifles, you just crab a new piece and drop it on (for the most part atleast).
As far as caliber variants go the list would be a nightmare to try to type from memory so here we go:

223 and based upon that case
6 x 45
7 x 40
357 Mag Rimless
300 Whisper (also other calibers)
6.5 x 40
30 Coyote (30 x 45)
17 Remington
17 Mach IV
20 Tactical
19 Calhoun

.22LR
.17 rimfire

5.7 FN (developed by Rhinland Arms - no word yet on who is going to mfg it)

204 Ruger

6.8 SPC
30 HRT
338 Spectre
10 mm Mag
35/40
219 WASP-C

7.62 x 39
338 x 39
6 PPC
6.5 Grendel
22 PPC
7 sCAR ....

30 Carbine
5.45x39

7 BR
6.5 BR
300 Sabre

8mm (belt fed upper)
.308 (again a belt fed upper - no longer available)

458 SOCOM
44 Mag
440 CorBon
44 AMP
.475 Tremor
50AE
499LW
50 Beowulf

.50 BMG (single shot)
.50 Blackpowder (1 made)

9mm
45ACP
32ACP
22 LR
17 HV
10mm
7.62x25
224 BoZ
7.62x24
9x23
357 Sig
40S&W

223 WSSM
243 WSSM

Forget where I found this at, copied it to a document that I was keeping info in, and didn't grab the author.

Posted: 4/17/2008 8:40:38 PM EDT

[#2]

so that would mean i should be able to take a 6.8 or 7.62 x 39 upper receiver with barrel , bolt assembly etc and pair it with my 5.56 lower rec and it should work?

Posted: 4/17/2008 8:49:32 PM EDT

[#3]

Yep, in theory.

Posted: 4/17/2008 10:27:53 PM EDT

[#4]

Quoted:
Yep, in theory.

As long as your upper and lower mate, and you have the correct mags, you should be okay.

Some caliber changes (i.e. 9mm and 223) require a different buffer to be placed in the stock, to aid in proper cycling, also, blowback designs (read: pistol calibers) are a little harder on the action and require special parts in the fire control group.

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AR-15 » Build It Yourself

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