Air Arms Owners Club

What size is it? I might have one in my collection
Any clues how best to remove and fit?

Assuming you mean the seal in the breech, it's the usual 4.5x1.5 nitrile, 70 Shore that, as far as I know, all the 400/500 series use.

Removing it is easy (in fact almost automatic ), just hook it out. Replacing it is more of a hassle. I use a length of 4mm wooden dowel down the muzzle, held in place with insulating tape, as a backstop to prevent the o ring going past the seating groove, and then fiddle it in with 2 small Allen keys.

If your HFT500 is anything like mine, I'd make sure you have plenty of spares - it's probably the weakest part of the whole design and you might find yourself becoming a bit of an expert

Happy fiddling...

Alan

Thank you Alan.
To confirm, that is 4.5mm od x 1.5mm cs ?
It is the getting the old one out that is usually the challenge!

4.5 ID hopefully!

ah yes; 4.5mm od would leave quite a small id !!

Yep, ID.

I've never had any problems getting them out - they're not held in place by anything except their own rigidity (if that's the right word). I use an old dental pick, but any sort of a hook will do the job fine, just be careful not to scratch the metal.

Alan

Use a cocktail stick with a bit of grease to ease it out.

BBF