These days it seems all the rage to make a piston driven AR. I have read about several different companies that make them. But I have not heard anyone here, or anywhere else for that matter, talk about the piston design from ZM weapons. Is their version not a good one or is it just not a well known company? I know that Todd Jarrett uses them so someone knows of them. Just something that I stumbled across and need more info on.
The ZM is not a piston design.
I was flipping through an old gun rag the other day and I saw a ZM weapons ad. I was wondering what happened to that company.
Correct.
The ZM uses a shortened carrier and like a AR-180 and Para FAL the recoil/buffer springs are up inside the upper receiver. This allows for a side folding stock. Todd Jarrett uses one because he’s sponsored by them. It’s a flat recoiling smooth shooting rifle especially when used with a suppressor or with a muzzle brake/comp.
They are still around. YHM is the exclusive distributer for them.
http://yhm.net/store/lr.html
IMHO they are heavy and expensive, but YHM sells a ton of them, my neighbor has one and he and his wife both love it and have no complaints about it.
Sorry I thought they were
The operating spring is outside of the receiver, over the barrel.
It was my understanding that it used an elongated gas key that extended above the barrel and that the buffer spring was wrapped around the key.
I haven’t seen one in a very long time, hopefully somebody knows better than I…
Tha’s correct. The carrier key extends through the front of the upper. It mates with a rigid gas tube that extends back from the gas block, and is inserted into the carrier key for a few inches. The op spring goes around the carrier key/op rod, is retained by a metal collar that slips into a recess machined into the end of the carrier key, and impinges against a steel bushing that protects the front of the aluminum upper receiver.
It’s really a very clever design.
Do you or have you ever had one?
I’ve never had one. My uncle had one of the old models, before the rail system. I shot it almost every weekend for as long as he had it.
http://myoutdoortv.com/pdk/web/rl-popupplayer.html?feedPID=gCeF3EIwxvnAJfUlOIYKGOOra24TBvbg
7th video on the list has an interview with Zitta and shows him field-stripping the rifle. couch_potato’s description is 100% correct, though he forgot to mention that the key never comes off the gas tube during operation (I forgot too).
This leads me to a question: Is the fundamental difference between a long-stroke gas piston (ala AK or Garand) and a DI system like Zitta’s that the piston slips into the gas chamber, versus a “key” slipping over a “tube”???
Anybody?