AR Calibers that use same bolt/magazine

[northark147]

I am considering doing an AR build using one of the quick barrel change kits from

http://dry-fire.com/the-tac2-ar15-discreet-carry-kit

I would like to make it multi-caliber just by changing the barrel and reloading the magazine. I know 5.56 and 300BLK, and am pretty sure another combo is 6.8SPC and 6.5G. 7.62x39 and 50Beowolf I believe use the same bolt but different magazines. Can anyone think of any others?

 

[Quiet]

6.8SPC uses a different magazine than the 5.56x45mm magazine. The internal dimensions are different.


.458SOCOM and .50Beowulf can be used in standard 5.56x45mm magazines.

 

[JustinJ]

To run the 6 x 45 all one needs is a barrel swap. Same bolt and mags. IMO this round holds the best promise for a military caliber upgrade.

 

[northark147]

6.8SPC uses a different magazine than the 5.56x45mm magazine. The internal dimensions are different.

Thats why I said another combo.. he 6.8 and 6.5 use the same magazine and bolt if I am not mistaken the 6.5 may use a 7.62x39 bolt, I can't remember for sure... I know they can't use either from a 5.56.

.458SOCOM and .50Beowulf can be used in standard 5.56x45mm magazines.

I think you would need to have a 7.62x39 bolt for the Beowolf plus bend the feed lips on the mag, Don't believe the SOCOM uses a 5.56 bolt either. Someone please correct me if I'm wrong..

To run the 6 x 45 all one needs is a barrel swap. Same bolt and mags. IMO this round holds the best promise for a military caliber upgrade.

So so far we are up to a 5.56, 6x45, and 300BLK with nothing but extra barrels.

 

[Z-Michigan]

556, 6x45 and 300BLK is your ticket.

6.8 SPC and 6.5 Grendel use different bolts and different magazines. No mas.

The 6.5 Grendel bolt is close but not identical in dimensions to a 7.62xx39mm bolt.

 

[Tirod]

You can find lists of what cartridges are available for the AR15 magwell, and then cross check the case head size by the drawings on Wikipedia.

Not necessarily authoritative, but it sorts out pretty quick with dimensions to .001".

Case in point (pun intended,) the .30-30 can potentially be re-rimmed, cut down, and made into 6.8 brass. More work than it's worth, but the point is the drawings were a quick and easy way to see it was possible. The Wiki on the AR lists many of them.

 

[68wj]

6.8 and 6.5 use different bolts. Mag bodies are the same, w/ different followers.

6.5 Grendel and 7.62x39/5.45x39 CAN use the same bolts, but it depends on the barrel maker. A true SAAMI 6.5G barrel needs a bolt with a deeper face and is not interchangeable with 7.62 bolts. Some barrel makers are headspacing off 7.62 bolts for ease of use, but G users will tell you that this isn't a 6.5G barrel, just one that shoots 6.5G ammo.

There are bushels of cartridges that share the .223 case head, but most are wildcats except for the latest .30 cal push.

For 6.8 SPC variants, there are some interesting loads out too (I am liking the 6mm DTI) including the .338 Spectre.

There are also several loads that use Grendel or x39 brass.