• Welcome to the DeeperBlue.com Forums, the largest online community dedicated to Freediving, Scuba Diving and Spearfishing. To gain full access to the DeeperBlue.com Forums you must register for a free account. As a registered member you will be able to:

    • Join over 44,280+ fellow diving enthusiasts from around the world on this forum
    • Participate in and browse from over 516,210+ posts.
    • Communicate privately with other divers from around the world.
    • Post your own photos or view from 7,441+ user submitted images.
    • All this and much more...

    You can gain access to all this absolutely free when you register for an account, so sign up today!

Question on Repairing a Mares Sten

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.


New Member
Mar 3, 2005
Hi All
I recently pulled the old antique pnumatic out of the closet and decided I gonna bring it back to life.
I pumped it up and used it for a while (worked fine), then when pumping it up again, it started to leak through the back where you stick the pump in.

I drained all the air and dismantled it from the back and checked the seals, they appeared ok. The problem is that while all the air was out, the trigger locked and when I try to pump it up again, it's not filling up with air and I cant seem to release the trigger.
Is there any way to release the trigger, maybe bang the gun against a wall :hmm
I think When you screwed the rear assembly back in you twisted the whole barrel unit which in turn put the hole for trigger pin out of line. (cause of jamming)discharge all air from gun remove trigger (one pin in trigger guard) pull out vertical pin ( which goes up through outer barrel to trigger sear to release ) Also check rear unit(spring -bearing and O ring are working Ok ).when this unit is free of gun attach to pump ensure air is one way only. hope this makes sense all the best Old Dave
That make sense because the pin(looking in from the back) inside is slanted and I suspected that the entire barrel has turned.How do I turn it back? Is there a special tool that I need. I see that looking into the barrel that there are two grooves, maybe to turn or remove the barrel ? The rear unit is working fine, however if I screw the bearing in all the way, it's pretty hard to pump?
Try gripping front end of barrel gently twist back into place if this fails i think strip gun right down and reassemble starting with inner barrel and handle and pump fitting plus trigger(this way you can see all is correct) next put back outer barrel finally front end assembly screw on gently ! otherwise you will barrel twist again

ps rear unit must not be tight. it contains a spring and a ball bearing which compresses when pumping to let air in.
DeeperBlue.com - The Worlds Largest Community Dedicated To Freediving, Scuba Diving and Spearfishing


ISSN 1469-865X | Copyright © 1996 - 2024 deeperblue.net limited.

DeeperBlue.com is the World's Largest Community dedicated to Freediving, Scuba Diving, Ocean Advocacy and Diving Travel.

We've been dedicated to bringing you the freshest news, features and discussions from around the underwater world since 1996.