That’s generous of you.All the ones I have seen have had hydraulic buffers. I surely doubt that the original buffers would retain their original “WE” (equivalent weight) which would make them unsafe to fire. I have seen many K3 hydraulic buffers fail from not being exercised and/or improperly stored. I would be happy to help anyone with manufacturing a new M7 hydraulic buffer should anyone want to fire theirs.
Are you in the manufacturing industry?