Qb 78-d

[Doc Sharptail]

My newest to me air rifle, bought new from scopes and ammo:



There's a lot more detailed "figure" to that stock, than what the photo shows. My camera's getting funky with a close to full s/d card :P





It didn't group like that out of the box- the burrs around the transfer port hole inside the bbl had to be cleaned up first. I also had a bit of trouble getting the tube cap to seat properly- the inside of the tube was pretty wrinkled. A bit of work with some 600 and 1000 weight wet/dry paper got it to where it will seat the o-ring seal properly.



This is how the brass trigger is done on the "D". It's dove-tailed on to a standard trigger. It is retained by a set screw through the back of the trigger.

I'm pretty pleased with this rifle. I haven't chronied it yet. For a .22 air rifle, it's the loudest in my collection. I really like the dimensioning of the stock. It fits me well, and the soft rubber butt pad is a true non-slip.

I removed the sights and mounted a Bushnell Banner 3.5-10X .17 Varminter. Point of balance is about the mid point of the wrist. As it's set up now, it's balanced well for off hand shooting.

There's major plans afoot for this rifle- each bit as I can afford it. First up will be a HPA tube for it, and then a hand pump of some sort. I'll even have a spare valve to play around with...

For anyone considering the "D", I say go for it- If you are prepared to do a bit of work de-burring the metal parts. For sure, the barrel and bore will have to be cleaned of all that brown cosmoline. The bbl shank and inside of the breech will need the burrs removed as well. Cheap insurance is ordering a seal set with the gun- the bbl o-rings come pre-shredded from the factory. These points are in no way a detraction from the gun- considering the price, it is still a bargain. Doing a little clean up work seems to be the norm for the QB series, from what I've read. I like this gun a lot....

Regards,

Doc Sharptail

[SeanMP]

Congrats Doc

You have that shooting sweet. I'm running my '78 on HPA as well but just on the stock tube.

[Doc Sharptail]

I played around with it a bit more, the last couple of nights.
I switched out the trigger spring for a slightly lighter, more finally coiled one. Big difference in the way the gun behaves off the bench. It definitely likes the 16 gr. Predators:



That flyer on the bottom was me getting excited, seeing 3 go into the same hole- I neglected to wait a bit for the tube to warm between shots...

It's a bit on the warm side for a sub-PAL gun. The 14.3 gr Daisy h.p.'s averaged 535.1 fps over the chrony. The predators average 507 fps, and the 18.1 gr. exact heavies are at 491 fps. The JSB Exacts are the most consistent velocity wise with a max deviation of 7.4 fps. I think they will group better once I get the breech end of the bbl totally cleaned up. Only fly in all this ointment was one low shot over the chrony- a Daisy h.p. only managed 68.8 fps. That was one shot only- and I'm guessing at this- factory crud in the valve. I haven't had the gun stripped down as far as the valve out yet.

Gun's a bit of a pig on co-2. With the 12 Gram Daisy cartridges, I'm seeing 39-40 usable shots- then get a sudden drop of p.o.i. of almost 2". From that point, the gun shoots down to empty with 6 shots. Won't be much of a concern once I get it set up with the HPA tube. That tube shipped today. I'm like a little kid hanging up a Christmas stocking with the wait :P

Regards,

Doc Sharptail

[Doc Sharptail]

I finally got it over the chrony last night. Shot count is a bit on the low side. I'm seeing 39-40 usable shots- then get a sudden 2" drop in p.o.i. Gun shoots down on 6 shots from that point. The tube on this one chills sort of rapidly- ice cold to the touch on just one shot. I'm using daisy cartridges right now.

I was a bit pressed for time, so elected to shoot 5 shot strings. Gun's a little on the hot side with anything lighter than 18 grains...

Daisy 14.3 gr h.p.

1.) 534.0
2.) 527.7
3.) 68.80 ? X
4.) 542.0
5.) 534.5
6.) 537.3

Avg.: 535.1



Dunno what happened with shot #3 on that string. Possibly debris in the valve. I haven't had the gun taken down to the valve out yet. That will come....

JSB Predator 16 gr poly tip

1.) 507.1
2.) 504.3
3.) 511.2
4.) 509.6
5.) 504.5

Avg.: 507.3



This bbl shoots well with the predators, despite the tight to close bolt when they're being loaded.

JSB Exact Heavy 18.1 gr Dome

1.) 494.2
2.) 490.9
3.) 491.4
4.) 487.8
5.) 494.4

Avg.: 491.74




It's going well with this gun, so far. I really should tear into it soon, but I'm having quite a good time shooting it. It's kind of hard for me to put down, yet. Got a bit of co-2 to shoot off too, before the carts get stale- they're almost 2 years old now...

I put swivel studs on the gun, and swapped out that coarse coiled heavy trigger spring for a slightly lighter, much more finely coiled one. Big improvement in the trigger pull. Got a bit more playing around to do with the over-travel adj. screw- it could be a bit better yet.

Regards,

Doc Sharptail

[Scottster]

Yeah, theses are great rifles for the price...
I often use one full CO2 bulb and a dummy (a used one I painted red) to keep the speed down with lighter pellets. Shot yield also goes down, but not by half as you might expect-usually to around 30 shots before POI's affected.
Your milage may vary.

[Dukemeister]

Good going Doc. My 2078 responded very well to a bit of polish and new seals. I'm very impressed by these 78's - I may have to get a D model to tinker with.
Sean are you using a regulated air bottle on your 78? Or just pumping 'er up and shooting?

[SeanMP]

Sean are you using a regulated air bottle on your 78? Or just pumping 'er up and shooting?

I'm doing most of my shooting by filling the tube to 1500 psi and shooting down to about 650. If I want to spend some hours at the bench testing pellets etc I attach to the bottle regulated to 850psi

[Dukemeister]

I'm doing most of my shooting by filling the tube to 1500 psi and shooting down to about 650. If I want to spend some hours at the bench testing pellets etc I attach to the bottle regulated to 850psi

Maybe this is the first "thread jack" on the forum.... so might as well enjoy:
How many good shots between 1500 and 650 psi?

[SeanMP]

Heavy on the YMMV here Duke

I get 30 shots at my target velocity which is 480fps

[Doc Sharptail]

I've been doing a little work on my 78.

Point of impact kept shifting to the left, until there was no adjustment left in the scope for it.



There's a definite crease around the crown there.
I cleaned it up a bit with a brass screw and some 600 wt wet/dry auto body paper.



It groups like this now for 10 shots at 12 meters with the 16 gr. JSB Predators. Getting there.



It started again pulling to the left. I readjusted the scope once more, and it seems to be holding. I really think I can do better with this. I'm tempted to order in one of Brownell's crown cutting tools. It's time consuming work, with the brass screw, and auto body paper. I'm really hoping the breech end of the bbl isn't going to require the same amount of attention...



Haven't even got into the valve end of the tube yet.







A lot of the screws in the gun are going to have to be replaced. That is the way they came from the factory, and evidence inattentive use of air operated screw drivers.

I wish I had more time to put into this. I like the gun a lot, and there's still heaps of potential there....

Regards,

Doc Sharptail