Air Arms Owners Club

I have acquired a 4ltr dumpy MDS bottle from a friend who has given up shooting, unfortunately (and I don't know why) it hasn't got a gauge on it. It is a 300bar in test til 2021 in almost new condition. So I need a gauge, 2 questions, there appears to be 2 sizes, I'm thinking its a rear fitting 1/8 thread. Anyone know if this is correct, and after phoning MDS (talking to a salesman, not a tech) he was unable to answer my question satifactually. He also said fitting of a new gauge (by me) could incur injury, death or worse. It looks like a straightforward parallel thread, how hard can fitting be ?. Anyone who's fitting one before, a few pointers would be great. Thanks.

If fitted with an airgun fill valve they are usually rear mount 1/8 bsp taper with ptfe tape. If there's a machined face to screw it up to then parallel with a dowty washer may be needed.

Best fittings do them for about £25.

Post a photo in imgur or flickr and post it here if not sure.

If it looks like this it should be a taper thread so you finish up with it the right way up.

Thanks for your help, it is exactly like the one in the pic you've posted.

Right. 1/8 taper and use ptfe tape and a SPANNER. Dont wind it in with the gauge body. They are delicate. Mine was flattened by the scuba shop as they (presumably) chucked em in the van. Divers tanks don't have delicate bits on like ours. Didnt notice til I got home!

wind the tape on clock wise whist the thread is facing you. This helps to stop it unavailing as you screw on.

BBF

Thanks everyone for your advise, much appreciated.