HiPAC on a QB78 ?

Joined: November 14th, 2015, 5:30 pm

December 14th, 2015, 2:52 pm #1

Since I'm new to the QB line of airguns, I ran across this. If I installed on of these tubes, would that be all I need to turn my '78 to a PCP and back to CO2 if I wished ?

Seems like an easy conversion. How many of you have used this system ?

I know on You Tube there is a guy that sent a tube through his leg, but he made the very, very big NO NO of playing around a PCP or CO2 gun with pressure in it !

wll

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Joined: April 6th, 2010, 4:08 am

December 14th, 2015, 3:10 pm #2

I just did this, and it is straight forward if you order the RIGHT SIZED HIPAC.
Alex has updated his webpage and made it very clear based on the end cap you have which HIPAC to order.
Follow the new directions, and make sure you list which QB78 in the check out notes you have, and he'll send you the right one.

Drop the black seal down the air tube, use something long to seat it in the valve head. Screw in the HIPAC, fill and shoot.

I fill mine to 1700 PSI with one extension, I get about 18 good shots at 800 fps with CPL pellets.

It's the perfect quest gun in my opinion.

JSD
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Joined: November 14th, 2015, 5:30 pm

December 14th, 2015, 4:59 pm #3

That is just the info I was hoping to hear. I'll talk to him to see what size tanks or/and extensions I should get and go from there.

Thank you again.

wll2506
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Joined: November 17th, 2006, 3:51 am

December 15th, 2015, 1:05 am #4

Since I'm new to the QB line of airguns, I ran across this. If I installed on of these tubes, would that be all I need to turn my '78 to a PCP and back to CO2 if I wished ?

Seems like an easy conversion. How many of you have used this system ?

I know on You Tube there is a guy that sent a tube through his leg, but he made the very, very big NO NO of playing around a PCP or CO2 gun with pressure in it !

wll
Just a couple of things.

Need a valve, or at least the front (silver) part of a valve, that is unmodded. There is a HiPac seal that is going to fit in the valve body recess, and the typical porting/slotting/opening up of that part by co2 hot-rodders won’t let it work with a HiPac.

Did spend the $ for a custom stock (straight grip), but it’s pretty much standard besides that (and the shortened barrel). It doesn’t shoot any better or worse when installed in a standard stock, I just wanted to try (1) a straight grip/c1 type stock and (2) wanted to pretty it up a little with nicer wood.

Valve is pretty secure as it is in a QB. There is a large steel ring that the valve is suppose to butt-up against. That steel ring is held in place by the stock bolt from the bottom and a pretty beefy breech screw. So long as the valve does butt up to that ring, it’s secure enough without adding any extra retention screws.

So basically I took the whole rifle apart and got valve out of the gun to fit the black HiPAc seal. Idea was to clean and chack everything was in good shape before reassembly as a HiPAc.


Checked to see the valve butted up solid against the internal steel ring (as it is suppose to). As this one did, I didn’t add any extra fixation screws.
Screwed in the HiPAc firmly by hand.



Filled with air.

Tuning gets complicated after that….striker spring tension, fill pressure, transfer port, valve mods (mostly if you aren’t thinking of going back to 12gr.), bolt probes, etc. Doesn’t really HAVE to get complicated, can pretty well just follow the rifle’s lead and let it decide how it wants to shoot (most of us are controlling, and mod a rifle to shoot what we want it to shoot).


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Joined: November 14th, 2015, 5:30 pm

December 15th, 2015, 1:43 pm #5

So the HiPac slides into the tube of the QB78 ?, I'm new and did not realize that ?

So All I do is remove the seal on the guns valve, reinstall and install the Hipac unit and that is it ?. that is easy as heck
Again, How many shots you getting with what pellet and what velocity ?

Thank you for your help.

wll2506
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Joined: December 18th, 2009, 3:35 pm

December 15th, 2015, 2:21 pm #6

Noticed they are out of stock.. :( nt
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Joined: November 14th, 2015, 5:30 pm

December 15th, 2015, 6:25 pm #7

This could be exactly what I'm waiting for ... just don't know how many shots to expect with CPHP pellets in .22 or what speed I'll get ??

wll
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Joined: December 18th, 2009, 3:35 pm

December 15th, 2015, 6:35 pm #8

Its a lot of tuning for a qb to get a decent shot string. I know Tom on his Halley got about 14-15 good shots per fill. With some valve changes delrin popit... lighter striker who know how much that could be improved if any.

Bruce
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Joined: December 18th, 2009, 3:35 pm

December 15th, 2015, 6:36 pm #9

This could be exactly what I'm waiting for ... just don't know how many shots to expect with CPHP pellets in .22 or what speed I'll get ??

wll
http://www.network54.com/Forum/113813/t ... with+HiPac
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Joined: November 17th, 2006, 3:51 am

December 15th, 2015, 10:44 pm #10

Since I'm new to the QB line of airguns, I ran across this. If I installed on of these tubes, would that be all I need to turn my '78 to a PCP and back to CO2 if I wished ?

Seems like an easy conversion. How many of you have used this system ?

I know on You Tube there is a guy that sent a tube through his leg, but he made the very, very big NO NO of playing around a PCP or CO2 gun with pressure in it !

wll
IT’s a tiny air volume, so a lot of higher powered shots just isn’t going to happen. Can add extensions to increase volume. I’ve not done that as I don’t mind the short shot count on a hunting rifle and I’m not real fond of adding more threaded/o-ringed joints to the system.
It’s pretty much of a blank slate. Can play with striker spring tension and get it running well at about 2600-2800psi for a good bit of power…or run it with co2 type spring tension at about 1600-1800psi for less power. Strangle it off to slower speeds for more lower powered shots, or open it up for fewer high powered shots.

Figuring out that balancing act between striker spring tension, stringer weight, transfer port size, and fill pressure is pretty much what PCP’s are all about….but I’d keep expectations for long long shot counts at a pretty uniform velocity pretty low.

(Here is my deal with HIPacs….will tune looking for whatever energy I can get with 20 uniform shots. Rather than having energy as my goal, I’ll accept the energy as the variable and keep 20 shots as the goal.)

However, because of the way the HiPac works, can really only count on the air inside the valve to power a shot…and that air is limited by the valve’s internal volume….so getting much past 15-16 foot pounds in .177 or 19-21 foot pounds in .22 takes some valve volume mods.

These are the 4 I still keep running
1 = (in the back ground) .177
2. 5mm 2250 isn’t running on HiPac anymore…in process of converting back to an HPA bottle).
3. .177 2260
4. .177 QB78
5. .22 2260


If you can find a good PCP tube (and I’ll have to look around now, as the one supplier for this air tube is long gone), the QB can be converted to PCP as well.

Did that with a .25 upper on this PCP tube. Also not a big volume tube, so also not going to get a whole lot of shots per fill….but as a PCP, the power can be pretty high (have had it up to 60 foot pounds, but normally run it at about 45 foot pounds for a longer good shot count).

Or if you’ve the urge, can convert them to regulated 13CI HPA bottles. Have done that to full length tube 78’s as well as the 79 (but with the 79, it’s a pretty easy conversion).

L to R:

5mm QB78
.22 QB 79
.177 AR2078



With some work (kind of like plumbing) could get the tanks to point backwards…and inlet the stock for the tank…and have a reverse bottle conversion. I’ve resisted that as I’ve more of a liking for fore ends that are comfortable to my hand that fat bottle sized fore ends (but if you shoot from sandbags, it makes little difference).
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