AR gas piston upper

[Jeff H]

I know this is rifle Country, but this is where all the AR guys hang out.

I stumbled on this pic while looking through AR pics on Google but I don't have any details. What kind of gas piston upper does away with the buffer tube entirely? and can I buy just the upper or is this only available if you buy the whole pistol at once?

 

[justin22885]

ive seen some piston AR uppers that have a long-stroke piston with the spring over the piston like on the sig 551 rifles, this eliminates the need for a spring behind the carrier and so the carrier can be shortened to a length that doesnt require a buffer tube

that particular rifle though has a recoil spring inside the oprod/piston portion of a new BCG which does the same thing

the main problem in making these systems work is you generally cannot just fit a piston through the front of the AR-15 upper receiver, you have to clear the AR-15 barrel nut which is why this particular gas system has been raised up so much higher

 

[briansmithwins]

What rifle/upper are those pics from?

BSW

 

[justin22885]

What rifle/upper are those pics from?

BSW

rock river arms PDS i believe