A few unexpected delays, but the pistons and main cylinders were shipped today! So at some point next week the build will start.
The plan is to build one up as a recoilling version to start with, just to check it's all sealing as it should, and the trigger is safe. Then I'll build the second up as a full fat recoilless version.

Whilst I've been waiting for these parts, I've been costing up a production version. Tentatively looking around £900. It initially seems a lot for a springer, but it will be low production, hand built, and completely recoilless. In this world of £2000+ mass produced PCP's, maybe £900 isn't so bad