Would this work well with a QB78?

[dryanw]

Would this be a good tank for use with my QB? I'm looking to get away from CO2 and use HPA.



And how does shot count compare to a 20oz CO2 bottle?

[dukemeister]

It will work with a coil tether, and give you about 30 fps more than CO2 at 70F.
My 48 ci tank gives about 500-600 shots between 3000 and 1500 psi on the tank. I generally refill the tank at 1500 psi. The nice thing about HPA is it's free or nearly free (once you have the equipment) and shot to shot consistency is tops! No need to worry about cold temps and cycle time, just shoot till you run out of air.

[dryanw]

Cool, thanks for the info. I plan to tether. Our guns look almost identical. Where did you get the brass barrel band? And the muzzle brake?

[dukemeister]

Where did you get the brass barrel band? And the muzzle brake?

Muzzle weight is my own concoction, and the band I bought from a local supplier: Scopes and Ammo (he doesn't ship outside of Canada). Similar bands are available worldwide. The barrel band and 2 grub screws did the job on that barrel. It's a nice consistent shooter.

[dryanw]

Would you mind elaborating on how you made your muzzle weight? It looks nice.

[dukemeister]

Nothing to it, it's a piece of brass pipe just over 15mm ID and matched to the OD of the stock muzzle weight. It sticks about 3/4" proud of the muzzle. They are butted together, and I put a couple grub screws in the brass to keep it in place. Then I stuck a small piece of 1/2" stainless tube in 3 O-rings and stuffed it down the end of the brass muzzle weight. 

[dryanw]

Well nice work. It looks good.

[mcc1961]

Can I fill a HPA tank like that with my Benji pump or would I have to buy an adapter?

[dryanw]

Can I fill a HPA tank like that with my Benji pump or would I have to buy an adapter?

^This

[woodant]

I don't see why you would not be able to.

As long as the fittings are correct you can refill a scuba tank if you wanted to.

Just give the pump some breaks and you should be alright.

This is my long term goal with the QB79.  To be able to refill larger tanks with a hand pump.

But then again, I don't own either one so I could be full of it! 

[dryanw]

What is the standard fitting for filling HPA tanks? My local dive shop was wanting to know what type of fitting the tank I wanted (linked at top) had. I wasn't sure and still haven't ordered it because of this.

[woodant]

Have a look at reply #8 by huklbery.

http://www.gatewaytoairguns.org/GTA/index.php?topic=39216.0

[Mebits]

Have a look at reply #8 by huklbery.

http://www.gatewaytoairguns.org/GTA/index.php?topic=39216.0

This is what I am doing myself. I'll let you know how it works as soon as I put my tank on.

M

[dryanw]

Just ordered the tank. I'm excited. CO2 kinda stinks. I did a test the other day.  Rifle strapped in a rest, so no user error, all rifle. 1 target I shot 5 shots @ 10 yards with 5 minutes between shots. One hole group. Second target I only waited 30 seconds between shots. .70 inch group. Not cool. This was indoors @ about 70 degrees.

[Mebits]

Just ordered the tank. I'm excited. CO2 kinda stinks. I did a test the other day.  Rifle strapped in a rest, so no user error, all rifle. 1 target I shot 5 shots @ 10 yards with 5 minutes between shots. One hole group. Second target I only waited 30 seconds between shots. .70 inch group. Not cool. This was indoors @ about 70 degrees.

Wow! My first time out with the 79 on CO2 in the basement, at about 65 degrees, I was barely waiting 30 seconds and I shot a 6 shot 1/4"ctc group. That was with a "flyer". I literally put 3 in the same undifferentiated hole. The next time out, I shrank that to 1/8". My range is ~45'.

Still, I was noting some real performance variation when I rushed a shot and the longer I shot. Some groups opened up to 3/8" just from only giving it 20 seconds (so hard to wait!!!). I DID bring a hand warmer down to try to keep the tank from getting too cool, but it wasn't doing that much good.

Air is going to be a godsend.
M

[Mebits]

Update: I ordered this tank http://www.ebay.com/itm/Ninja-Aluminum-HPA-Tank-Nitro-Air-13-3000-GS-Series-SHP-Reg-1100-PSI-/170945977925?pt=LH_DefaultDomain_0&hash=item27cd2c9e45

That's a bit spendy but safe and holds a lot of air and is regulated to 1100psi (adjustable down) and comes with an adjustment ring to keep your fill nipple and gauge readable. (DO NOT do this with a full tank!) It's also much lighter than 9oz CO2.

I followed these instructions: http://www.network54.com/Forum/113813/thread/1320616282/HPA+QB79+and+78+tanker+conversions

It does require taking off the tank and the barrel. Do so carefully so you don't cut the O-rings (if Mike tuned it, you probably don't need to worry about the rings). Then spin the tank on, loosen the adjustment ring and spin your fill nipple to where you want it then tighten down with the allen wrench.

Slide the barrel back into place and tighten the band screw and the retaining screw.

Then pump it up.

I did, to 3000 PSI. I saw no evidence of leaking. So I took it to the range.

First of all I shot 6o shots. Initially my scope was way off. After sighting in, the RWS HP's were doing 2/10" groups. and the RWS Domes were doing 3/10" groups. I note that after 60 shots I was still at 1500-1800psi (I'll have a better idea once I put it back on the pump). I had figured on only getting 50 shots so this is a pleasant surprise.

I don't have a chrony but my best guess is that the guns is shooting RWS domes at 800fps, maybe a tad more (probably less than 900 fps no matter what). That's plenty of power as far as I can tell (~22 ft/lbs).

I'm pleased, to say the least.

[dryanw]

I wish the tank I ordered went to 900-1000psi rather than 800 but oh well. They are generally not adjustable, right?

[Mebits]

Some are, some may not be. I'm no expert! :O LOL!