What caliber upper is compatible with this lower?

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[ARCHIVED THREAD] - What caliber upper is compatible with this lower?

Posted: 9/9/2018 1:33:22 PM EDT

I have a s&w sport one lower, came with my 223/556 upper. I purchased a 300 blackout Upper and it fit perfectly. What other caliber uppers could I mate to this lower with proper compatibility? I’ve heard a lot of fan talk re 6.8 and 6.5 for people that like to use these guns for hunting. Made me wonder if these are calibers that could be added to my lower to expand the function..

Posted: 9/9/2018 2:04:22 PM EDT

[#1]

I am going to assume this is an honest question and you're not trolling.

All AR15 uppers regardless of caliber will fit all AR15 lowers. The specs are military standard.

Posted: 9/9/2018 2:09:11 PM EDT

[#2]

.17 HMR to .50 BMG. It's an extensive list.

Posted: 9/9/2018 2:27:01 PM EDT

[#3]

Quote History

Quoted:
I am going to assume this is an honest question and you're not trolling.

All AR15 uppers regardless of caliber will fit all AR15 lowers. The specs are military standard.

View Quote

Yes, was an honest question, perhaps a dumb one. I know the 308 won’t work with my ar15 lower, believe it requires a heavier duty lower , ar10 I think. That made me wonder what other calibers require a different lower. Anyway, it wasn’t long ago that I learned about the whole upper thing whereby the 300 blackout could be attached to my lower so have been wonder what other calibers will work with my lower so that I don’t need to purchase another Lower.

Posted: 9/9/2018 3:09:15 PM EDT

[#4]

6 x 45
7 x 40
357 Mag Rimless
300 Whisper / .300Fireball / 300-.221
6.5 x 40
.30 Coyote (30 x 45)
.17 Remington
.17 Mach IV
.20 Tactical
.19 Calhoun
5.7 FN
.204 Ruger
6.8 SPC
30 HRT
338 Spectre
10 mm Mag
35/40
219 WASP-C
7.62 x 40
5.45×39
7.62 x 39
.338 x 39
6 PPC
6.5 Grendel / 6.5 AR / 6.5 PPC Improved
22 PPC
7 sCAR
30 Carbine
5.45×39 / .21 Ghengis
7 BR
6.5 BR
300 Sabre
8mm
458 SOCOM
44 Mag
440 CorBon
44 AMP
.475 Tremor
50AE
499LW
50 Beowulf
.50 BMG
.50 Blackpowder
9mm
45ACP
32ACP
22 LR
17 HV
10mm
7.62×25
224 BoZ
7.62×24
9×23
.357 Sig
.357 Auto
40S&W
223 WSSM
243 WSSM

Posted: 9/9/2018 4:31:38 PM EDT

[#5]

Quote History

Quoted:
6 x 45
7 x 40
357 Mag Rimless
300 Whisper / .300Fireball / 300-.221
6.5 x 40
.30 Coyote (30 x 45)
.17 Remington
.17 Mach IV
.20 Tactical
.19 Calhoun
5.7 FN
.204 Ruger
6.8 SPC
30 HRT
338 Spectre
10 mm Mag
35/40
219 WASP-C
7.62 x 40
5.45×39
7.62 x 39
.338 x 39
6 PPC
6.5 Grendel / 6.5 AR / 6.5 PPC Improved
22 PPC
7 sCAR
30 Carbine
5.45×39 / .21 Ghengis
7 BR
6.5 BR
300 Sabre
8mm
458 SOCOM
44 Mag
440 CorBon
44 AMP
.475 Tremor
50AE
499LW
50 Beowulf
.50 BMG
.50 Blackpowder
9mm
45ACP
32ACP
22 LR
17 HV
10mm
7.62×25
224 BoZ
7.62×24
9×23
.357 Sig
.357 Auto
40S&W
223 WSSM
243 WSSM

View Quote

WOW! Thank you.

Posted: 9/9/2018 5:11:53 PM EDT

[#6]

Quote History

Quoted:
6 x 45
7 x 40
357 Mag Rimless
300 Whisper / .300Fireball / 300-.221
6.5 x 40
.30 Coyote (30 x 45)
.17 Remington
.17 Mach IV
.20 Tactical
.19 Calhoun
5.7 FN
.204 Ruger
6.8 SPC
30 HRT
338 Spectre
10 mm Mag
35/40
219 WASP-C
7.62 x 40
5.45×39
7.62 x 39
.338 x 39
6 PPC
6.5 Grendel / 6.5 AR / 6.5 PPC Improved
22 PPC
7 sCAR
30 Carbine
5.45×39 / .21 Ghengis
7 BR
6.5 BR
300 Sabre
8mm
458 SOCOM
44 Mag
440 CorBon
44 AMP
.475 Tremor
50AE
499LW
50 Beowulf
.50 BMG
.50 Blackpowder
9mm
45ACP
32ACP
22 LR
17 HV
10mm
7.62×25
224 BoZ
7.62×24
9×23
.357 Sig
.357 Auto
40S&W
223 WSSM
243 WSSM

View Quote

You left out 30 Rem AR

Posted: 9/9/2018 5:29:28 PM EDT

[#7]

Quote History

Quoted:
You left out 30 Rem AR

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
6 x 45
7 x 40
357 Mag Rimless
300 Whisper / .300Fireball / 300-.221
6.5 x 40
.30 Coyote (30 x 45)
.17 Remington
.17 Mach IV
.20 Tactical
.19 Calhoun
5.7 FN
.204 Ruger
6.8 SPC
30 HRT
338 Spectre
10 mm Mag
35/40
219 WASP-C
7.62 x 40
5.45×39
7.62 x 39
.338 x 39
6 PPC
6.5 Grendel / 6.5 AR / 6.5 PPC Improved
22 PPC
7 sCAR
30 Carbine
5.45×39 / .21 Ghengis
7 BR
6.5 BR
300 Sabre
8mm
458 SOCOM
44 Mag
440 CorBon
44 AMP
.475 Tremor
50AE
499LW
50 Beowulf
.50 BMG
.50 Blackpowder
9mm
45ACP
32ACP
22 LR
17 HV
10mm
7.62×25
224 BoZ
7.62×24
9×23
.357 Sig
.357 Auto
40S&W
223 WSSM
243 WSSM

You left out 30 Rem AR

There's likely a few missing.

Posted: 9/9/2018 8:08:35 PM EDT

[#8]

Quote History

Quoted:
Yes, was an honest question, perhaps a dumb one or ,when I asked the wrong question. I know the 308 won’t work with my ar15 lower, believe it requires a heavier duty lower , ar10 I think.

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
I am going to assume this is an honest question and you're not trolling.

All AR15 uppers regardless of caliber will fit all AR15 lowers. The specs are military standard.

Yes, was an honest question, perhaps a dumb one or ,when I asked the wrong question. I know the 308 won’t work with my ar15 lower, believe it requires a heavier duty lower , ar10 I think.

You are on the right track, there are (basically) 2 AR lowers. AR10 and AR15. It is a tad more complicated than that, because of different patterns, but it's an easy way for you to remember, and talk about it here.
Think about it in terms of bullet length, or magazine width. The AR10 lower is for the high power rifle calibers in the longer .308 length.
When I talk here about mine, I call it my .308 lower.

*Before you savages jump my shit, I am just trying to give him an easier way to remember

Posted: 9/9/2018 8:41:33 PM EDT

[#9]

Quote History

Quoted:

*Before you savages jump my shit, I am just trying to give him an easier way to remember

View Quote

Lol

Posted: 9/9/2018 8:59:34 PM EDT

[#10]

Quote History

Quoted:

You are on the right track, there are (basically) 2 AR lowers. AR10 and AR15. It is a tad more complicated than that, because of different patterns, but it's an easy way for you to remember, and talk about it here.
Think about it in terms of bullet length, or magazine width. The AR10 lower is for the high power rifle calibers in the longer .308 length.
When I talk here about mine, I call it my .308 lower.

*Before you savages jump my shit, I am just trying to give him an easier way to remember

View Quote

There are three sizes, but the medium size is not common. It's the LWRC Six8 lower, made to use Magpul mags with the 6.8 for the Saudi military. A polymer mag won't work with intermediate cartridges based on the 6.8 or 6.5G case in a standard lower. The cases push outward too hard, and the internal mag capacity can't be made large enough to hold them and be thick enough to withstand the forces while still fitting in the mag well.

Only Six8 uppers and those based on it will mate to the lower.

Posted: 9/9/2018 9:12:22 PM EDT

[#11]

There are many. I am liking my 450 Bushmaster upper a lot.

Posted: 9/9/2018 11:49:28 PM EDT

[#12]

Quote History

Quoted:

Yes, was an honest question, perhaps a dumb one. I know the 308 won’t work with my ar15 lower, believe it requires a heavier duty lower , ar10 I think. That made me wonder what other calibers require a different lower. Anyway, it wasn’t long ago that I learned about the whole upper thing whereby the 300 blackout could be attached to my lower so have been wonder what other calibers will work with my lower so that I don’t need to purchase another Lower.

View Quote

300 Blk is a derivative of the .223 cartridge, so naturally it uses the same bolt and magazines. With the AR-15, if it fits in the magwell, they can probably chamber it. The exception is if the cartridge doesn't use the magwell, or it's mag well attached to the upper receiver, then it's possible to go up to .50 bmg, a muzzle loading barrel , and even a crossbow.

.308 and similar length cartridges use the AR-10 action. There are even larger AR derivative actions designed to accept 300 Win Magnum and 12 gauge shotshells.

Posted: 10/31/2018 11:44:23 PM EDT

[#13]

Quote History

Quoted:

Yes, was an honest question, perhaps a dumb one. I know the 308 won’t work with my ar15 lower, believe it requires a heavier duty lower , ar10 I think. That made me wonder what other calibers require a different lower. Anyway, it wasn’t long ago that I learned about the whole upper thing whereby the 300 blackout could be attached to my lower so have been wonder what other calibers will work with my lower so that I don’t need to purchase another Lower.

View Quote

Not a dumb question. I usually try to think bolt face and rim size.

378 rim diameter cartridges - AR15

473 rim diameter cartridges - AR10

Even then there are so many odd balls I have to double check.

Posted: 11/1/2018 12:08:40 AM EDT

[#14]

Quote History

Quoted: 473 rim diameter cartridges - AR10

View Quote

Other than the .458 SOCOM in the AR-15.

Posted: 11/1/2018 9:31:12 AM EDT

[#15]

Quote History

Quoted:

You are on the right track, there are (basically) 2 AR lowers. AR10 and AR15. It is a tad more complicated than that, because of different patterns, but it's an easy way for you to remember, and talk about it here.
Think about it in terms of bullet length, or magazine width. The AR10 lower is for the high power rifle calibers in the longer .308 length.
When I talk here about mine, I call it my .308 lower.

*Before you savages jump my shit, I am just trying to give him an easier way to remember

View Quote

This pretty much sums it up. If you have any specific caliber questions post them in the Variants forum.

If an upper is advertised as 'AR-15' compatible, you should be good. Blowback pistol calibers can get a little more complicated but if you're looking to pick up an upper in 6.8spc or 6.5grendel it's gonna be a direct fit to any standard AR-15 lower. Buy an upper w/BCG, the appropriate mag, and start shooting.

Posted: 11/1/2018 9:34:13 AM EDT

[#16]

Just know that different upper/calibers that fit on the ar15 lower will require different mags and BCG to function. Just make sure you research and buy the correct parts before you shoot it.

The most common ar15 size calibers are probably 300BO, 6.5 Grendel, 6.8 SPC, and 224 Valkyrie. There are others like the one listed above, but these ones probably have the most parts and availability

Posted: 12/2/2018 4:01:44 AM EDT

[#17]

Although the upper and lower dimensional specs are the same for all AR-15s, there are different types and weights of buffers used depending on barrel length (and possibly other factors). My question is: Do I need to change buffers and/or springs when I switch from a .300 BLK with a 16" barrel to 5.56 with a 20" barrel?

Posted: 12/2/2018 10:38:51 AM EDT

[#18]

Quote History

Quoted:
Although the upper and lower dimensional specs are the same for all AR-15s, there are different types and weights of buffers used depending on barrel length (and possibly other factors). My question is: Do I need to change buffers and/or springs when I switch from a .300 BLK with a 16" barrel to 5.56 with a 20" barrel?

View Quote

From a stock gun, probably unless you use an adjustable gas block, which I would do o any caliber I would be shooting both subs and supers from.

Even then you'll find most folks run a H2 weighted buffer and sometimes an H3. You won't know until you shoot it for sure exactly what weight you want. Build it, and shoot it with a standard buffer, and see what your brass looks like ( unlocking early and causing swipes ), and what the ejection pattern is, and if the recoil seems too harsh. If any or a combination of those things are present, then you will need to add weight.

Posted: 12/3/2018 1:20:38 AM EDT

[#19]

Quote History

Quoted:
There's likely a few missing.

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
6 x 45
7 x 40
357 Mag Rimless
300 Whisper / .300Fireball / 300-.221
6.5 x 40
.30 Coyote (30 x 45)
.17 Remington
.17 Mach IV
.20 Tactical
.19 Calhoun
5.7 FN
.204 Ruger
6.8 SPC
30 HRT
338 Spectre
10 mm Mag
35/40
219 WASP-C
7.62 x 40
5.45×39
7.62 x 39
.338 x 39
6 PPC
6.5 Grendel / 6.5 AR / 6.5 PPC Improved
22 PPC
7 sCAR
30 Carbine
5.45×39 / .21 Ghengis
7 BR
6.5 BR
300 Sabre
8mm
458 SOCOM
44 Mag
440 CorBon
44 AMP
.475 Tremor
50AE
499LW
50 Beowulf
.50 BMG
.50 Blackpowder
9mm
45ACP
32ACP
22 LR
17 HV
10mm
7.62×25
224 BoZ
7.62×24
9×23
.357 Sig
.357 Auto
40S&W
223 WSSM
243 WSSM

You left out 30 Rem AR

There's likely a few missing.

you missed .20 Practical as well

Posted: 12/5/2018 11:25:52 AM EDT

[#20]

missed the .222 Remington and .204 Ruger

CD

Posted: 12/8/2018 4:14:35 AM EDT

[#21]

Quote History

Quoted:
There are three sizes, but the medium size is not common. It's the LWRC Six8 lower, made to use Magpul mags with the 6.8 for the Saudi military. A polymer mag won't work with intermediate cartridges based on the 6.8 or 6.5G case in a standard lower. The cases push outward too hard, and the internal mag capacity can't be made large enough to hold them and be thick enough to withstand the forces while still fitting in the mag well.

Only Six8 uppers and those based on it will mate to the lower.

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:

You are on the right track, there are (basically) 2 AR lowers. AR10 and AR15. It is a tad more complicated than that, because of different patterns, but it's an easy way for you to remember, and talk about it here.
Think about it in terms of bullet length, or magazine width. The AR10 lower is for the high power rifle calibers in the longer .308 length.
When I talk here about mine, I call it my .308 lower.

*Before you savages jump my shit, I am just trying to give him an easier way to remember

There are three sizes, but the medium size is not common. It's the LWRC Six8 lower, made to use Magpul mags with the 6.8 for the Saudi military. A polymer mag won't work with intermediate cartridges based on the 6.8 or 6.5G case in a standard lower. The cases push outward too hard, and the internal mag capacity can't be made large enough to hold them and be thick enough to withstand the forces while still fitting in the mag well.

Only Six8 uppers and those based on it will mate to the lower.

Which is why I posted "there are (basically) 2 AR lowers" and even put a caveat at the bottom of the post.

For the purposes of this thread, the 2 common sizes are appropriate information, I felt.

Posted: 12/17/2018 12:49:07 AM EDT

[#22]

This is a tremendously helpful thread.

https://www.ar15.com/forums/t_3_123/734513_Collecting-cloning-building-using-hunting-with-the-AR-15-a-presentation-Input-requested-.html

[ARCHIVED THREAD] - What caliber upper is compatible with this lower?

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