First post so be gentle with me.
I bought a 300r recently and I am having
trouble cocking it and I think the trigger
unit is at fault and as I have a spare 52 trigger
unit I thought I would try that,
does anyone know if they are interchangable.
With the gun cocking? What makes you believe it's the trigger unit that is the fault or the cause? Don't take these questions wrong, I'm just trying to get information. As far as the interchangeability goes, if they are the same series i.e TO1, T05 etc, I would imagine they would (could) interchange. If you are having issues with your guns performance you could send it in for warranty work? I have a 300R as well and I have noticed no difficulty in cocking. If your is defective I'm sure RWS Service Center will make it right.
HTH
V/R Nathan