Air Gun Home :: View topic - Waterproof QB-78

Alstone · Moderator & Site Supporter

Last summer if you can call it that I went out a few times in wet weather rat hunting, now this is alright it you don’t mind getting you gun wet, so for shooting in the rain I use a QB78 because it was cheap, also light and if it fell in the river it would still work.

The only problem with it is that because of the way the bolt assembly is designed it collects water, so to rectify this I did a small mod to the bolt, it only took two hours to make using the lathe, to do the mod with out one would be difficult. But after saying that the drawings took considerably longer. Apart from anything else it looks nice and keeps the water out.

Have fun

Al

jonathan · Member

Wow, that is great.

Amigo · Veteran Member

Al:

Good engineering and excellent execution. Patent it.

You Are Good Exclamation

Best regards,

Amigo

kanyon · Silver Status Member

very nice....Yer a skilled machinest Smile

broommaster2000 · Moderator

That looks great. I want that. Mr. Green

Brutuz · Senior Member

Good job

broommaster2000 · Moderator

Seems to me mine needs that too. It will shoot much better because of that mod. Mr. Green

yourdaddyjoe · Supporting Member

Hey Al,

I have been thinking about one of these but the QB79 and putting a JDR HPA 1600 psi regulated tank on it... Thoughts?

Joe

Alstone · Moderator & Site Supporter

Crosman140 · Senior Member

Al, now you and broom can get together with your 78's. Weeeeeee Shocked

Alstone · Moderator & Site Supporter

I suppose someone has to add a bit of class to the site. Mr. Green

yourdaddyjoe · Supporting Member

Yea... and put more holes in his walls... Mr. Green

The only issue is with the fill nipple hitting the barrel. I orderd some "Myth" low profile foster fittings for Guy's 2250 HPA w/JDR Tank & Regulator set up and they work great. A whole 1/4" shorter. Just make sure you use enough TFE tape on the fitting... Oooops...

broommaster2000 · Moderator

Right now I'm considering this mod, I got a friend who can do some work on his lathe. His can only do round objects though, not sure how it's called in English if you can also go from the top but the bottomline is that he can't very well do that with his rig... Neutral

So how do you narrow that part where you do the pellet?

Alstone · Moderator & Site Supporter

It's not a problem Anton, that flat is allready there, it's to clear the screw that holdes the reciver down, also the new tube that slides over the loading port does not need the cut out on the drawing, just file a little bit off the top of the reciver screw and it should fit.

One other thing when you turn the bolt back to fit the tube, only turn it back as far as the cutout, also while the bolt is out check that it is not bent as most are, this is caused by machining the cutout in the bolt and taking too much off in one cut.

If it is bent then clamp it between two pieces of aluminium in a vice, behind the cutout, then tap the front of the bolt with a hammer and a piece of wood, keep checking until it is stright.

Al

broommaster2000 · Moderator

Al,

I didn't mean the flattened part, I've been there, taken the gun apart two times already. Mr. Green

I was talking about the clearance of the "pellet bed". Neutral

There ain't much room there now so how do I make space for the cover?

By the way, I did the trigger polishing mod, which worked out great. The trigger is nice and light. Also polished the bolt and the "pellet-bed" or how you call it.