With all the AR piston stuff I had to wonder...

[Autopistola]

Has anyone ever bothered to make an AR upper like that of an AR-180?

Plenty of makers have a similar version of the same short-stroke piston, but when it comes to the upper reciever they retain the AR-15 style of cylindrical bolt carrier.

I know manufacturers improvised things to deal with carrier tilt. ('skis' on the bolt carrier, specialized buffers, different piston/carrier angles, etc.)

I just want to know if the upper could be/has been converted to a more rectangular shape for a rectangular bolt carrier. The AR-180 seemed like a good idea to me, but with todays technology it could be adapted to be even better...attached to a modified AR lower of course, and perhaps an Ace folder as well.

EDIT: duh...It's late and I'm tired, but I was just cruising the web and ran across pics of the Robinson XCR, FN SCAR, and the ACR came to mind too.

 

[Tirod]

Precisely. A properly designed piston gun has it's own proprietary bolt which is usually tall and rectangular. It's also short and runs on rails.

It's the bandaid guns that still use a Stoner bolt, deactivate the piston in it, put another one on the barrel, and sell the results. Kinda like removing direct cylinder injection on an engine and putting a carburetor on top. Something old Fudds are likely to do because they won't bother to understand advances in technology.

It's actually illegal to do with cars - EPA and all that. With guns, the magic of marketing makes it seem like an attractive proposition. Look at how political parties do so well.

Doesn't say much about the American consumer.