Yep, any standard bar hop rubber will fit them. I've currently got a madbull one in mine but have used TM, guarder and maple leaf. The maple leaf one ...

@Razorlight many thanks for that - I'd actually seen those prints from people making Star Wars props however am taking my project in a slightly differ...

The gearbox doesn't necessarily need to be connected to the trigger though - a simple remote microswitch running from above the trigger to the gearbox...

Appreciating the responses so far - as I said I never had any troubles being there in kit but this was 5-6 years back and attitudes might have changed...

Interesting stock sort of (the history of it) - looked "duffle cut" to me on the front end at first glance as there doesn't look a small eno...

Pete - you're not thinking of turning to the "dark side" I hope or you eyeing it up for an axis conversion. Would be interested in a deta...