AR15 Calibers that Use 5.56 Bolt

Are there others? I'm not aware of any. A lot of other calibers use the same carrier but require a bolt swap.
 
I had heard that some of the big bore calibers used the same bolt but came up short in my search

I think they generally use a larger bolt face. Even the weird rebated rim cartridges like 50 Beowulf have bigger bolt faces.
 
I forgot about the TCU series of wildcats. They're mostly seen in Contenders, not ARs but they're all 223 necked up to 25, 6mm, 6.5mm, 7mm and 30.
 
@Boghog1

350 legend is basically a straight walled .223. AFAIK same bolt as a .223 AR. Aside from hunting, I see ZERO point in this cartridge but it does exist.

Can't speak to 224V but 6mmARC has a larger boltface than 5.56

Yes this is my understanding. The 224V is a necked down 6.8 rem. 6mm arc is a necked down 6.5 grendel, which is derived from .300 russian

both require larger bolt face but the 6.8 rem / 224V dont push the limits of an AR bolt nearly as much as the 6arc or 6.5 grendel. the latter cartridges leave very little steel for bolt lug support. They all seem like interesting ideas until I compare them to a 69 or 77 gr 223 rem and the juice isn’t worth the squeeze (speaking just for my purposes).
 
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@Boghog1

350 legend is basically a straight walled .223. AFAIK same bolt as a .223 AR. Aside from hunting, I see ZERO point in this cartridge but it does exist.



Yes this is my understanding. The 224V is a necked down 6.8 rem. 6mm arc is a necked down 6.5 grendel, which is derived from .300 russian

both require larger bolt face but the 6.8 rem / 224V dont push the limits of an AR bolt nearly as much as the 6arc or 6.5 grendel. the latter cartridges leave very little steel for bolt lug support. They all seem like interesting ideas until I compare them to a 69 or 77 gr 223 rem and the juice isn’t worth the squeeze (speaking just for my purposes).

I think with Valkarie and other high(er) velocity .224 calibers the main issue is finding relatively heavy match grade .224 bullets that can handle the velocities. I know there are some more now that Nosler came out with their caliber but still not nearly as many to choose from as 6mm for example.

I had some success with another 6.8 SPC based wildcat called .240 Tomahawk. Basically a 6.8 necked down and fire formed for 6mm. Lots of match grade 6mm bullets to choose from, and very accurate in an AR-based match gun. It was also nice to be able to stock the same 6mm Bergers that I use for 6XC. I don’t think it’s even available anymore though.
 
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