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Calibers in a Standard AR15 Lower

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April 27, 2017, 03:53 PM
LS1 GTO
Calibers in a Standard AR15 Lower
If one were to have an extra AR15 lower, what caliber uppers can it support?

Is a unique lower kit required (other than the magazine itself)?





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April 27, 2017, 04:00 PM
sreding
There is a pretty complete list here - detailing what is needed (Barrel, bolt head, mag etc).

https://www.frontiertactical.com/calibers/
quote:

Calibers requiring a barrel change only (using a standard mil-spec, 5.56 NATO, AR-15):
.17 Remington
.17-223
.20 Practical
.204 Ruger
.25-45 Sharps
5.56x45mm NATO/.223 Remington
6x45mm
.300 AAC Blackout

Calibers requiring no barrel change if used with a conversion kit (using a standard mil-spec, 5.56 NATO, AR-15):
.22 LR (conversion kit is commonly supplied with one magazine)

Calibers requiring a barrel, bolt and magazine change (using a standard mil-spec, 5.56 NATO, AR-15):
5.45x39mm (5.45x39mm bolt, barrel and magazine)
6.5mm Grendel (6.5mm bolt, barrel and 6.5mm/5.56mm NATO magazine)
6.8mm Remington SPC II (6.8mm Rem. SPC II bolt, barrel and magazine)
7.62x39mm (7.62x39mm bolt, barrel and magazine)
.243 LBC (.243 LBC bolt, barrel and 6.5mm/5.56mm NATO magazine)
.264 LBC (.264 LBC barrel, 6.5mm/.264 LBC bolt and 6.5/5.56mm NATO magazine)

NOTE – Our BHW .264 LBC barrels are “Type I” (bolt depth of .125″), and use a common 7.62x39mm bolt to fire .264 LBC or 6.5mm Grendel.
American 30 BHW (American 30 BHW barrel, 6.8 Rem. SPC II bolt and magazine)

Calibers requiring a barrel, bolt, modified upper receiver and magazine change (using a standard mil-spec 5.56 NATO AR-15):
.450 Bushmaster (.450 Bushmaster barrel, bolt, magazine and modified upper)
.458 SOCOM (.458 SOCOM barrel, bolt, 5.56 NATO magazine and modified upper)
.50 Beowulf/12.7x42mm (.50 Beowulf/12.7x42mm barrel, bolt, magazine and modified upper)




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April 27, 2017, 08:04 PM
LS1 GTO
That is what I was looking, thank you.





Life moves pretty fast. If you don't stop and look around once in a while, you could miss it.



"If dogs don't go to Heaven, I want to go where they go" Will Rogers

The definition of the words we used, carry a meaning of their own...



April 29, 2017, 06:28 PM
zoom6zoom
There are also uppers that don't require use of the original magwell in the lower, so that really widens the field too. I have one customer upper that has it's own side feeding mag (probably one of very few built in 7.62 Tokarev), and there are some .50BMG uppers that are similar

There's also a 5.7×28mm upper that uses the original magwell as the ejection chute.



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