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 Post subject: QB78 Mods today?
PostPosted: Sun Feb 23, 2014 10:10 am 
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Joined: Thu Aug 02, 2007 7:54 pm
Posts: 356
Location: Quebec, Canada
Alright so nothing to do today, and I've been thinking about taking apart my QB78 for a while now, but it's so accurate now that i don't want to make it inaccurate, let me know what you guys think, should i take it apart, tune it and polish the inside, mod the valve? is there any chance of me doing something wrong and damaging it? or make it inaccurate in away of modding it?


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 Post subject: Re: QB78 Mods today?
PostPosted: Sun Feb 23, 2014 10:30 am 
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If your happy with the accuracy and power of the QB why bother.

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 Post subject: Re: QB78 Mods today?
PostPosted: Sun Feb 23, 2014 11:41 am 
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Location: Kingston, ON
If you want to learn something and gain some experience and have nothing better to do, then pulling it apart may be a worthwhile exercise. I'm assuming you haven't yet been inside your 78 and that it has stock/original components. If it's shooting great and holding gas, then you got a good one. Eventually, the seals will leak and you'll have to at least change the seals in it. I suggest you don't pull it apart unless you have a seal kit on hand, because the factory seals will likely not survive the tear-down process. I suppose you could make it worse (inaccurate) by tearing it apart... but most things people do to the 78 make them better.

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 Post subject: Re: QB78 Mods today?
PostPosted: Sun Feb 23, 2014 2:00 pm 
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Location: Quebec, Canada
well took it apart, added a nut between the spring and hammer, polished the hammer, and also opened up the valve en sanded down a bit of brass off the valve stem, drilled a bigger hole for the air to go through, changed the breech seal, and drilled the probe a bit bigger, also the oval hole on the of the probe hole which lets the air pass, added an aluminum washer instead of the foam part of the piercing stem, got it back together and shot it and re-zeroed the scope, and its still shooting great! accurate as before and seems a bit more powerful! no leaks encountered :)


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 Post subject: Re: QB78 Mods today?
PostPosted: Sun Feb 23, 2014 5:29 pm 
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Joined: Sun Jul 15, 2012 10:49 am
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Location: Victoria, BC and Clarkston, WA
Ace wrote:
If your happy with the accuracy and power of the QB why bother.


Ditto!

Go shoot Patrick!!!

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 Post subject: Re: QB78 Mods today?
PostPosted: Tue Feb 25, 2014 9:16 am 
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Location: Calgary, Alberta
Pat, half the fun of this platform is the ease of disassembly and modding. Additionally, if you **** it up real bad, you're not out an a$$load of cash. I have had my 2079 apart so many times threads are starting to wear out and I'm not done with it yet.
You'll learn a lot about what works and what doesn't and the process is a great boredom beater.

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 Post subject: Re: QB78 Mods today?
PostPosted: Tue Feb 25, 2014 10:20 am 
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Location: Quebec, Canada
Handyguy wrote:
Pat, half the fun of this platform is the ease of disassembly and modding. Additionally, if you **** it up real bad, you're not out an a$$load of cash. I have had my 2079 apart so many times threads are starting to wear out and I'm not done with it yet.
You'll learn a lot about what works and what doesn't and the process is a great boredom beater.


True :) it didn't actually take alot of time plus, i had nothing to do that day and it killed a couple hours :) now that i know how to take it apart good!, i will buy myself a o-ring kit! although its sealing very well, i don't want to take the chance of redoing it again and scrapping an o-ring, as for the o-ring for the valve the white one, if i replace it with a black o-ring will that be alright? of i should buy a o-ring kit that are all white(if that exists)?


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 Post subject: Re: QB78 Mods today?
PostPosted: Tue Feb 25, 2014 10:27 am 
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Location: Kingston, ON
patfraser3 wrote:
i will buy myself a o-ring kit! although its sealing very well, i don't want to take the chance of redoing it again and scrapping an o-ring, as for the o-ring for the valve the white one, if i replace it with a black o-ring will that be alright? of i should buy a o-ring kit that are all white(if that exists)?

Barrel O-rings can be Buna-N (the most common black ones).
The end cap and valve should be made of a CO2 compatible material, Polyurethane (usually yellowish) or EPDM (mine are black) are good choices. if you get a kit from a reputable source than it should have the right materials. If you use Buna-N for the pressurized CO2 areas they will work for a while but they swell and maybe not last you very long. etter to get the right stuff IMO. :drinkers:

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 Post subject: Re: QB78 Mods today?
PostPosted: Tue Feb 25, 2014 10:30 am 
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Location: Quebec, Canada
Dukemeister wrote:
patfraser3 wrote:
i will buy myself a o-ring kit! although its sealing very well, i don't want to take the chance of redoing it again and scrapping an o-ring, as for the o-ring for the valve the white one, if i replace it with a black o-ring will that be alright? of i should buy a o-ring kit that are all white(if that exists)?

Barrel O-rings can be Buna-N (the most common black ones).
The end cap and valve should be made of a CO2 compatible material, Polyurethane (usually yellowish) or EPDM (mine are black) are good choices. if you get a kit from a reputable source than it should have the right materials. If you use Buna-N for the pressurized CO2 areas they will work for a while but they swell and maybe not last you very long. etter to get the right stuff IMO. :drinkers:


Great to know, i work in a garage, so the source for o-ring kit there are pretty much alot, but what works with cars may not work with Co2, i'm unaware of what they are made :S There is actually alot in the parts departement, which i can pick and have for free since they don't sell them alot. but they are black and they come from "Wurth" company and don't know what they are made of


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 Post subject: Re: QB78 Mods today?
PostPosted: Tue Feb 25, 2014 10:00 pm 
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Joined: Tue Aug 20, 2013 8:56 am
Posts: 1079
Location: Calgary, Alberta
patfraser3 wrote:
Handyguy wrote:
Pat, half the fun of this platform is the ease of disassembly and modding. Additionally, if you **** it up real bad, you're not out an a$$load of cash. I have had my 2079 apart so many times threads are starting to wear out and I'm not done with it yet.
You'll learn a lot about what works and what doesn't and the process is a great boredom beater.


True :) it didn't actually take alot of time plus, i had nothing to do that day and it killed a couple hours :) now that i know how to take it apart good!, i will buy myself a o-ring kit! although its sealing very well, i don't want to take the chance of redoing it again and scrapping an o-ring, as for the o-ring for the valve the white one, if i replace it with a black o-ring will that be alright? of i should buy a o-ring kit that are all white(if that exists)?


One thing I did right off the bat was, file the inside edges of all screw holes. If you run your finger along the inside of the tube you will find these are very sharp. It is these edges that will shear bit and pieces off the o-rings. I got a riffling file and worked these edges down. I don't have problems with shaved seals anymore.

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 Post subject: Re: QB78 Mods today?
PostPosted: Fri Feb 28, 2014 1:49 pm 
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Joined: Sat Feb 22, 2014 4:32 pm
Posts: 3
For o rings I use nbr o rings for barrel and probe and edpm for end cap and valve and I make my own tp seals out of PTFE rod of eBay which I drill different size holes for different power.


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 Post subject: Re: QB78 Mods today?
PostPosted: Fri Feb 28, 2014 8:54 pm 
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Joined: Sat Oct 19, 2013 10:26 am
Posts: 34
If it anit broke don't fix it.


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 Post subject: Re: QB78 Mods today?
PostPosted: Fri Feb 28, 2014 9:50 pm 
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Joined: Tue Aug 20, 2013 8:56 am
Posts: 1079
Location: Calgary, Alberta
Jack Frith wrote:
If it anit broke don't fix it.


No fix, make better.

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