QB79 Ninja - The $200 PCP

[nervoustrigger]

If memory serves, I was getting about 18fpe in .22 cal on 850psi with a QB78 so I don't think you'd have any trouble getting 12fpe even with the shorter tube and in .177, assuming that's the caliber you have in mind.

For good efficiency, definitely do the RVA mod.  Far and away the easiest way to tweak for power vs shot count.  You may also benefit from lightening the hammer but my advice is start with the RVA and do the hammer work afterwards if you aren't happy with the efficiency. 

[WECSOG]

Thanks, Jason. Yeah, my intention is to do the top-end mod Bob describes, make an RVA with a jam nut (which is how I usually do it) and do the valve front-end mod as both you and Bob describe. Your build thread was also a great incentive to get my own QB79. I have read it in its entirety more than once, and I read it again this morning.

My QB is .22 caliber. AD just sent notification that it has shipped.

[nervoustrigger]

Thanks Tracy, I always like hearing when one of my projects inspires others to take up something similar.

Seeing as how you're aiming for 12fpe in .22 cal, I suspect you will indeed benefit from lightening the hammer.  That energy level in a free-flowing rifle will require just the tiniest sip of air so a sharp tap on the valve stem with a light hammer should do the trick and minimize the opportunity for any bouncing that might otherwise waste air.

Definitely stick with the 850psi setpoint for this type of tune.  A SHP bottle at 1100psi is overkill and would only serve to make things more difficult to tame the tune down to 12fpe.

Shot count should border on the absurd.  An efficiency of only 1.25 will yield 200 shots per fill and it's not unreasonable to expect you might hit 250.

[WECSOG]

I'm liking the sounds of that! I'll take your advice, Jason, and stick with 850. Seems that will also help shot count in that it has a ways further to go before it hits the set point.

[rsterne]

At 850 psi you will have to significantly REDUCE the hammer strike or you will be wasting a huge amount of air.... Once you have the gun up and running, read my threads on tuning regulated PCPs....  http://www.gatewaytoairguns.org/GTA/index.php?topic=74919.

Bob

[WECSOG]

Thanks, Bob. Yeah, I know I'll have to reduce the hammer strike. I will probably swap in a lighter hammer spring and perhaps a lighter hammer as well, and make an RVA so I can easily adjust it.

[Tweeter]

All this talk about QB's and now I have one on the way...  A couple questions
  I plan to tear it down completely to de burr and polish everything, also to do some valve work.  Can anyone tell my the o ring sizes for the tank block and the valve?  What is the best o ring material when using hpa?
  I will be running the 13ci Ninja pro with 1100psi reg, should I replace the tank block screws?  Thanks guys!

[nervoustrigger]

-113 for the valve, -016 for the tank block (or metric 19mm OD x 2mm CS).  These are static O-rings holding air so Buna-N works great and they are inexpensive.  Durometer of 70A is good but the more commonly available 50A should work fine too.

Yes, definitely replace the tank block screws with some good quality M4 x 10mm socket head cap screws.  Bear in mind, however, that you don't need to crank them down super tight, just snug. All their load is in shear. 

[pllagunos]

Would you recommend replacing the stock o-rings and tank block screws with better ones if I am using a 850psi Ninja tank?

[nervoustrigger]

I suggest always replacing the screws because it's so inexpensive and if you own the rifle long enough, eventually the regulator will fail or the seat will creep and there will be >1500psi against them for some length of time until the 1.8k burst disk ruptures.

Regarding the stock O-rings, seldom will they survive disassembly due to burrs left from manufacture so attempting to reuse them invariably results in a frustrating hissing sound from your newly-assembled rifle that you're anxious to try out.  So yeah, plan to replace those too

[sr1sws]

I suggest always replacing the screws because it's so inexpensive and if you own the rifle long enough, eventually the regulator will fail or the seat will creep and there will be >1500psi against them for some length of time until the 1.8k burst disk ruptures.

Regarding the stock O-rings, seldom will they survive disassembly due to burrs left from manufacture so attempting to reuse them invariably results in a frustrating hissing sound from your newly-assembled rifle that you're anxious to try out.  So yeah, plan to replace those too

+1 on "eats original o-rings upon dis-assembly".  Even after de-burring, mine still manages to nick some.  Just replaced a barrel o-ring this afternoon.

Steve

[pllagunos]

  when I get mine I will try it bone stock with the regulator at 850psi, after that I think I am going to do the complete tune you did in your thread (amazing btw) however I will just attempt 19fpe since it is a .177

[Tweeter]

When I tuned my qb78 I polished the inside of the tube more or less to reduce the chance of nicking the valve o ring when I re assembled it.  Should this be done on the 79 also?  And does it get a very light coat of silicone grease?

[Airsnipe]

Can someone give me a link to the ninja reg that can be adjusted up to 3K? All I can find is up to 1100 or 850. I don't see anything anywhere that says you can order them adjustable to 3K.

[pllagunos]

You can't buy a regulator set above 1100 psi however you can adjust it yourself with an output tester and some belleville washers, take a look at this link: http://www.gatewaytoairguns.org/GTA/index.php?topic=49648.msg469843#msg469843

Also you don't want to regulate it to 3000 psi, I am not sure it would even work

[huklbery]

Can someone give me a link to the ninja reg that can be adjusted up to 3K? All I can find is up to 1100 or 850. I don't see anything anywhere that says you can order them adjustable to 3K.

The bottle is 3k so that would be remove the guts I imagine. Past that it use different combination of wave washers to give a static output pressure not an adjustable one on the fly so to speak.

[sr1sws]

When I tuned my qb78 I polished the inside of the tube more or less to reduce the chance of nicking the valve o ring when I re assembled it.  Should this be done on the 79 also?  And does it get a very light coat of silicone grease?

It's really the holes and slots that have burrs that cut o-rings.  Remove them and you should be good.  I don't see a reason to try to polish the entire interior of the tube.  Silicone grease = goodness for o-rings.  Apply before assembly.

Steve

[BigTinBoat]

Can someone give me a link to the ninja reg that can be adjusted up to 3K? All I can find is up to 1100 or 850. I don't see anything anywhere that says you can order them adjustable to 3K.

Here's a "non-adjustable" set to 2900

http://www.paintball-discounters.com/ninja-airgun-only-4500-psi-spa-regulator-2900-output/

[GarthThomas]

Can someone give me a link to the ninja reg that can be adjusted up to 3K? All I can find is up to 1100 or 850. I don't see anything anywhere that says you can order them adjustable to 3K.

I hope you aren't thinking of running a QB at 3000psi, that would be dangerous.

[GarthThomas]

Can someone give me a link to the ninja reg that can be adjusted up to 3K? All I can find is up to 1100 or 850. I don't see anything anywhere that says you can order them adjustable to 3K.

I hope you aren't thinking of running a QB at 3000psi, that would be dangerous. I was under the impression that anything over 1800psi was dangerous.