Bottled QB78

[Monkeydad1969]

So, if you were going to bottle a QB78, for HPA, what would you do? 

Would you:

Regulate?
Go bigger caliber---from .22 to .25?
Valve work?
What bottle setup?

Anything I missed?

Joe

[ShakySarge]

Stay with .22, get rid of filter and open up valve, pin valve, extend bolt probe with drill bit, def reg bottle. That is all I can think of at the moment bro!

Matt

[BigTinBoat]

Here's what I would do (did)....

http://www.gatewaytoairguns.org/GTA/index.php?topic=81046.0

Ends up looking like this:

[Monkeydad1969]

Thanks Matt.

Hey Rob,

What the numbers like for your QB?

FPS?
FPE?
Shot count?

[BigTinBoat]

Thanks Matt.

Hey Rob,

What the numbers like for your QB?

FPS?
FPE?
Shot count?

With the RVA I can set for anywhere from like 250fps to over 1000. Shot count will vary depending on velocity. FPE anywhere from like 2FPE to 19FPE
I have it set for about 12FPE and somewhere around 180 shots I think.
My results are real similar to Todd in his chart in this thread
http://www.gatewaytoairguns.org/GTA/index.php?topic=79948.0;nowap

[rsterne]

Whatever you do, stay with a 1.8K burst disc in the regulator, which means 1500 psi or less.... The QB is a CO2 gun, don't allow it to see more than what CO2 does on a hot day, unless you change a bunch of things....

Bob

[BigTinBoat]

Whatever you do, stay with a 1.8K burst disc in the regulator, which means 1500 psi or less.... The QB is a CO2 gun, don't allow it to see more than what CO2 does on a hot day, unless you change a bunch of things....

Bob

to add - my bottle is using the 1.8K and my output is just about 1350psi

[Monkeydad1969]

Thanks all.  I will have to think about that some more, but I am interested in possibly doing a bottle on my QB.

Joe

[Ribbonstone]

The simple version would be a tank-forward set up, but you have to like forward balanced rifles.

Pretty simple conversion (and I do have a fondness for simple).  Made several of them and have kept 2 (along with a 79).



Have found the long 78 tubes have an advantage.  With a large volume of pre-regulated air on tap, they are easier to tune.

Do have some restrictions (some already mentioned).

1. They are co2 guns. Stick to pressures inside the co2 window.  Some go higher, but 1200-1300psi is probably the best.

2. With a standard tank block (there were not other choices back when I made these) the limitation is the placement of the tank block screws.

(while I like the brass gauged on/off, you can live without it and shorten the length the tank hangs forward.)


Cutting off the threaded part of the tube is a good idea, as part of the strength is the thickness of the metal inside the above red circle.  Drill the smallest holes possible to let the screws pass to leave as much metal between the screw hole and the end of the tube.

3. Inlet the stock for the gas block and epoxy bed the block in place.  Want the support that offers.



Tuning them can be pretty easy.  Have a large volume of pre-regulated air between the bottle and the valve, so it’s a lot like tuning a CO2 rifle. Larger passageways and less valve “clutter” help for speed. Main “throttle” is the striker spring tension.

So for the “economy” version, would need:

1.  A gas block (either the standard QB79 block ($35) or the one with a new screw location from JDS ($70).

2. 13CC HPA tank.

4. Basic hand tools (hack saw, drill, drill bits, files, emery paper, etc.).

What I haven’t tried is the “new” gas block version with 4 o-rings.  Not that I think you need 4 o-rings, but that would give you a new rearward choice in screw location.

After experimenting with mine up to 1300psi, found that I could meet my goals (12-15 foot pounds) with just 800-850psi air.  Most of my tuning was to get to that energy area with between 150 and 205 shots per tank.

[SpiralGroove]

Hey QB Tuners,
A few basic questions that border on the naive as I know nothing about theses guns:
1) Can the regulated bottle be filled with a PCP pump?  If yes, what adapters are needed?
2) Since I already have 4 BAM B50/B51's, how does the QB79 selling for $100 on PA compare?
3) How much fun are these guns to shoot relative to the above BAM's?
I really don't need another project if this will be further duplication of my BAM's.
Any additional information is appreciated

[BigTinBoat]

Hey QB Tuners,
A few basic questions that border on the naive as I know nothing about theses guns:
1) Can the regulated bottle be filled with a PCP pump?  If yes, what adapters are needed?
2) Since I already have 4 BAM B50/B51's, how does the QB79 selling for $100 on PA compare?
3) How much fun are these guns to shoot relative to the above BAM's?
I really don't need another project if this will be further duplication of my BAM's.
Any additional information is appreciated

I can answer #1 - yes they can, I use my Air Venturi pump to fill mine EASILY. No adapter needed. The bottles have a male foster fitting for filling

[nervoustrigger]

Kirk,

They are loads of fun.  My .22 cal B51 is very accurate and the QB is every bit as accurate, if not slightly better.  Both are set up to shoot about 30fpe.

[SpiralGroove]

Hey Jason and BTB,  -> Thanks
I just read Bob's post from 2013, which (as usual) pretty much spells it all out.

It appears the regulated QB with stage 2 mods will cost about $250 ($100 gun + $80 regulated tank + other? stuff) vs. the BAM B51 at $300 ($209 + $80 for Milo74 reg. + springs & other materials).  Does this seem about right?
Jason: All things considered, IYO what would you rather shoot, the modified BAM or QB?

[BigTinBoat]

Hey Jason and BTB,  -> Thanks
I just read Bob's post from 2013, which (as usual) pretty much spells it all out.

It appears the regulated QB with stage 2 mods will cost about $250 ($100 gun + $80 regulated tank + other? stuff) vs. the BAM B51 at $300 ($209 + $80 for Milo74 reg. + springs & other materials).  Does this seem about right?
Jason: All things considered, IYO what would you rather shoot, the modified BAM or QB?

I got $120 in the gun
$40 in my bottle (used ebay)
$4.00 in LDC
$25 in stock, body filler
$7 in paint
That's all I can think of

[nervoustrigger]

Using all new parts, you are looking at these costs...pulled from memory:

$110 (for the 78 Deluxe, subtract 10 for the standard)
$60 for Ninja tank
$35 for tank block
$10 for misc screws and O-rings

The standard Ninja tank ($60) at 850psi is good for, say, 12 - 15fpe in .177, or probably 20 - 24fpe in .22 cal.  I am usually targeting higher energy in .22 cal so that number is a bit of a guesstimate. 

If you are going .22 and want over 30fpe, you want either a Ninja SHP tank ($90) or rebuild a standard Ninja reg for 1300 - 1500psi output.  Either way, you will need some assorted belleville washers to do that.  You did me a solid on the tapered springs for the B50 valve so let me know if I can help on the regulator or with the misc hardware.  I have about 80 O-rings left from every 100pk I've bought so don't hesitate.

By the way, getting the SHP up from its factory setting of 1100 to the 1300 or 1500 level isn't too bad with some trial and error.  Rebuilding a standard Ninja reg to the same pressure was a little more challenging for me but I've got it licked now

[nervoustrigger]

Kirk, as to which rifle I prefer, the QB78 is a 99% gun for me.  I love it.  Feeding it JSB 18.1gr, it delivers 60 - 65 yard *brain* shots on squirrels with utter confidence again and again as long as I'm not battling the wind.  Foxes, raccoons, and possums at 45 yards at night...it's a wrap.  Puts the JSB lead into the brain pan every time.

To be clear, that is from a rest--a less than perfect rest--but a rest nonetheless.  In field conditions, my human limits come into play and I like to keep shots inside of 45 yards.  But if you want to know the limits of the rifle itself, I haven't found them yet.  The longest shots I take are 70 yards and it delivers there.

[SpiralGroove]

Thanks Jason,  Glad you got the springs
Because I really don't want another project, do you think it's correct to say the QB's usefullness/versatility value is higher than a BAM B50/B51.

Since I don't hunt, a guns function judged on, it's accuracy, platform quality/simplicity, fun factor and shot count potential.  Anything > 20 FPE is gravy....

[Ribbonstone]

All three of the ones shown have been together for years (oldest about 7) without any problems other than the typical occasional bolt probe 0-ring.

It might be that they are actually less stressed than if they were running co2.  In my case, are running lower pressure and air is cleaner than co2, which might be some of the reason they’ve been trouble free.

No argument with those who want power, you can get it with these conversions even at low pressure.  Can also work them over to get a whole lot of uniform shots per fill.

One fill of the 850psi .22 QB79 in 5 shot groups (20yards):

[SpiralGroove]

Hey Guys,
I got a QB79 (.177) from AGD shipped for $95 -> God help me with the addiction --  Bob you're to blame

[Monkeydad1969]

Hey Guys,
I got a QB79 (.177) from AGD shipped for $95 -> God help me with the addiction -- Bob you're to blame

Now what did you say?  Oh yeah:

"Because I really don't want another project..."   LMBO!!!!!

Join the club, friend.

Joe