Things are not quite going as planned , and a MAJOR QUESTION ?

[wll2506]

My '79 with the valve mods and all including a 3/16 spacer for the hammer spring is giving me 845 with CPHP's ... I thought I would get more.

My QB78 is giving me 808fps with EXACT 15.9gr pellets, this again is with the new mini valve and a .350  spacer , I was hoping for more, but when I put on the 22ci tank the outgoing read 1475 psi ... to much for me, I'm taking a .005 shim out of it tomorrow, I don't want to go over 1400psi, I will have to make due. This much pressure may have been to much for even .350 worth of spring shims, shots sounded very short and crisp though..

Man alive I have done everything i thought by the book ... good news is nothing leaks ;- ) in either gun !

Now the question:  .... putting the breech back on the gun is just a PITA !!! especially with spring shims in it. I got it together by pulling a sting against one of the pins to move it in position ? WHAT DO YOU GUYS DO !!! ??

wll

[nervoustrigger]

It's easy to put it back together when it's cock on open with an RVA. 

Sorry, you know I had to

[Austringer]

I put the spring and shims in after I install the breach. Just line up the hammer, bolt pin with each other, install the transfer port seal, set the breach onto the tube and insert the breach/to tube screw and snug it up. I'd already have the trigger mounted by the foreword screw so as soon as the breach assembly is attached transfer is lined up, I install the spring assembly and cap, then the long rear trigger screw. Probably not the best description, but the point is I don't attach the breach assembly to the tube with the hammer spring already installed.

Oh yes, and that was with a cock on open mod.

I think your current performance is on par with what others are getting at your regulated pressure ratings. Yes, I wish I could get more for less as well, but that's just not possible....until Bob or Jason think of the next best thing since chocolate milk.

Troy

[BigTinBoat]

It's easy to put it back together when it's cock on open with an RVA. 

Sorry, you know I had to

yep, I've never run into a minutes trouble putting a QB breech on a gun.

[Ribbonstone]

Remember when you started this...your expectations for energy?

"All you can get" is a never ending goal....no matter how fast you get one running, there is always "one more thing" to try.

You got them both up to about 23 foot pounds....which is a pretty reasonable goal as the pellets are shooting in a very good range of velocity for accuracy.

Let me ask you two things:
(1) what kind of shot count are you getting (not guessed, but chronographed) for a full fill for each?
(2) if you switched to 21gr. pellets, what would the velocity/energy be (higher...but how much higher is a good indication of how it's tuned to air use).

[wll2506]

Remember when you started this...your expectations for energy?

"All you can get" is a never ending goal....no matter how fast you get one running, there is always "one more thing" to try.

You got them both up to about 23 foot pounds....which is a pretty reasonable goal as the pellets are shooting in a very good range of velocity for accuracy.

Let me ask you two things:
(1) what kind of shot count are you getting (not guessed, but chronographed) for a full fill for each?
(2) if you switched to 21gr. pellets, what would the velocity/energy be (higher...but how much higher is a good indication of how it's tuned to air use).

Both guns are too new and I have not chronoed them for shot count. We will see what happens what a drop in outgoing does, I think I will do that with both guns... It may be just a little bit less pressure, put it may allow opening up of the poppet a bit more.

I have not shot Kodiaks in it at all but I probably should. If getting 850fps with 18.1 gr Exact's are possible... 850-875fps should be possible with 15.89 gr Exact pellets. I do want 27-30 fps.... I would be very happy with 27fpe, as that gives me 16fpe+ at 60 yds, with is my long distance range.

This gives me confidence in long ground squirrel shots.

wll

[Ribbonstone]

Guess it's all about the confidence level.

If you want 16 foot pounds at 60yards, then that's what you should tune for.  If you need 20 or only 10, then that's what you should have. 

Won't negate that feeling, as that's what you want...so that's what you need to feel comfortable.

[wll2506]

Guess it's all about the confidence level.

If you want 16 foot pounds at 60yards, then that's what you should tune for.  If you need 20 or only 10, then that's what you should have. 

Won't negate that feeling, as that's what you want...so that's what you need to feel comfortable.

I will do my best to get the speed I need with the pellet I want, within reason of course !  ... 27 fpe is within reason with these guns for sure !

wll

[wll2506]

Did nothing to her today, she just sat overnight in a corner thinking about her poor performance yesterday ... Well today she came out swinging ... a good solid 865fps with CPHP ... for this gun that is in my zone.... I will remove a .005 shim when she runs out of gas just to see what happens, but if she looses speed, I'll put the .005 back in her and that is it with this gun.

She was getting 812 ish and at one time 835, but the 835fps days are long gone, that was the first few shots and once she settled in it was 812fps. So I'm happy with a 50fps increase in speed,

Worked on block for the '78 and once I got her home I realized I still need to make the groove about .560 .... .580 is just to big and the "O ring fits way to tight and is destroyed when I install it... so it is back to the lathe tomorrow. Now i see some progress... i just want to know who was working on my gun when I was asleep .... ;- )

As a side note a package from Wolf in Poland came in, he makes nice stuff !

wll

[Austringer]

Sounds great Wll. I just tuned my 79 to 880fps using cphp's which puts it at about 820 with 18.1 JSB's. That is with a drilled out tank block adding about 1 more cc of volume.  Still looking fore more. Probably ordering a 78 tube to add an inch or two of tube volume to hit my target of 30 fpe.

[wll2506]

Sounds great Wll. I just tuned my 79 to 880fps using cphp's which puts it at about 820 with 18.1 JSB's. That is with a drilled out tank block adding about 1 more cc of volume.  Still looking fore more. Probably ordering a 78 tube to add an inch or two of tube volume to hit my target of 30 fpe.

We are pretty much on the same page, I'm hoping lowering the outgoing, with the spacers I have pushes her to the 875ish with CPHP's ... if not, Oh Well 865fps is just fine for my gun ( this is a starling, pest bird gun, shooting cheap CPHP's to have fun with, although i will see what she gets with 18.1gr'rs just for kicks ;- )

Congrats on your speeds, I have not chrono'd mine with 18.1 gr pellets 820ish with 18.1's is 17fpe at 60 yds ... that's awesome ! You have yourself one powerful airgun there and that gun should be a real Jack Rabbit killer for sure ! You still have well over 15fpe at 75 yds ... if I was a Jack Rabbit I would move from your neck of the woods for sure ;- )

Nice going !

wll

[nervoustrigger]

William, you said you may try JSB 18.1gr just for kicks but I also see you talking about terminal energy at 60 yards.  Well, if you are content with CPHP at that distance, you really owe it to yourself to try the 18.1 but also the 15.9.  They may just put a smile on your face. 

[wll2506]

I have been chronoing 15.89gr EXACT pellets .. or so I thought at 808 fps ... well I had tape over the HEAVY part .... So I was getting 808fps with 18.1 gr heavies with my '79 ...WOW, that puts this gun into 26fpe at the muzzle and 17fpe at 60 yds .. this thing is now a cruncher ! All this time I have been using these and thinking they were 15.89gr Exacts !

I will remove a .005 shim to see is she steps it up, but velocity is dropping near the 1450 mark, so we will see.

I'm very interested in what she does with CPHP's too !

I'm flabbergasted at my stupidity and not looking closer at the tin, and just seeing the word Exact and not Exact Heavy

wll

[wll2506]

William, you said you may try JSB 18.1gr just for kicks but I also see you talking about terminal energy at 60 yards.  Well, if you are content with CPHP at that distance, you really owe it to yourself to try the 18.1 but also the 15.9.  They may just put a smile on your face.

Please read about my stupidity and not wearing my glasses !  Yes, there is a smile on my face ! I use the CPHP because they are cheap for plinking and starling shooting, I save the better pellets (Exacts) for real stuff ; - )

Ya know Jason when I was shooting the Exact Heavy pellets I was thinking to my self how hard they hit and how flat they were shooting at 60 plus yards, for a pellet weighing just a grain and a half more.... Now I know... I was comparing a 14.3 gr pellet in flight to a 18.1 gr pellet...and there was a noticeable difference, a 43% gain in ballistic coefficient, and it does make a difference !

wll

[Austringer]

That's pretty funny. My eyes are failing too. I wish JSB would package their products in a different color can or something. I could easily make the same mistake. Jason is right about considering the heavy JSB's for hunting. Almost guarantee you will see better accuracy AND the bc is way better than CPHP's. I think wind drift alone with the 18.1's is half that of the CPHP's.

In the beginning, my goal was to have an airgun that shot cheap CPHP's well. My Disco shoots them close to OK. My QB78 shoots them TERRIBLE, like 2' to 3" at 28 yards, so I have resorted to good JSB 18.1 which perform real well in both guns. And if you buy them in quantity with free shipping, they're not much more expensive then the crossmans. Well now, Wally World has dropped their price on CPHP's to $6.97 and this sweet little QB79 I put together seems to shoot them really well! Only squeezed 3 groups in before the little woman came home last night, but I got two 1/2' five shot and one 3/4" ten shot groups at 28 yards. I'm sure it can do better and I'm sure it will do worse, but I'm also betting the 18.1's will be outstanding. Time will tell.

I have a lot of work to do on the gun now. Need to fit a 78 tube to it, test the setup to ensure it meets my desire, then start on stocking it to my preference. I'm hoping to arrive at "the" airgun I will be happy with until...well, I don't know what until. We'll see. I still have a Disco I want to convert to a bullpup too.

Troy

[wll2506]

That's pretty funny. My eyes are failing too. I wish JSB would package their products in a different color can or something. I could easily make the same mistake. Jason is right about considering the heavy JSB's for hunting. Almost guarantee you will see better accuracy AND the bc is way better than CPHP's. I think wind drift alone with the 18.1's is half that of the CPHP's.

In the beginning, my goal was to have an airgun that shot cheap CPHP's well. My Disco shoots them close to OK. My QB78 shoots them TERRIBLE, like 2' to 3" at 28 yards, so I have resorted to good JSB 18.1 which perform real well in both guns. And if you buy them in quantity with free shipping, they're not much more expensive then the crossmans. Well now, Wally World has dropped their price on CPHP's to $6.97 and this sweet little QB79 I put together seems to shoot them really well! Only squeezed 3 groups in before the little woman came home last night, but I got two 1/2' five shot and one 3/4" ten shot groups at 28 yards. I'm sure it can do better and I'm sure it will do worse, but I'm also betting the 18.1's will be outstanding. Time will tell.

I have a lot of work to do on the gun now. Need to fit a 78 tube to it, test the setup to ensure it meets my desire, then start on stocking it to my preference. I'm hoping to arrive at "the" airgun I will be happy with until...well, I don't know what until. We'll see. I still have a Disco I want to convert to a bullpup too.

Troy

I don't really have that much more to do on the '79 except the shim thing in the regulator, and that is just a thing to try.

I did buy a 17ci tank for the '79 to give me more air volume and more shots when I am in the field with this gun.

My intent with the '79 was a starling slapper while I was parked under trees, so BC was not that much of an issue for the intended use. Sixty yard shots with CPHP pellets would be fine... I did not intend this gun to be a heavy hitter with CPHP pellets, but this speed and energy with Exact Heavy pellets changes my feelings about the intended use ! ----- It is quite obvious that this gun can be a very doable ground squirrel gun....to 75 yds, which is around 15 fpe at that range .... I do my job and it is over ..... This is a game changer for sure .

wll

[wll2506]

Building a QB can be a pile of pain, that's for sure.

My new QB78 at 1350+ outgoing (after I took out a .005 shim), with all the mods and .350" of spring shims is giving me 788fps with 18.1's, and 841fps with CPHP's---  lower than my QB79 ?

I only fired about 5 shots, and will shoot some more tomorrow. if she doesn't speed up, I'll pop in a couple more .040 shims as I don't want to get the outgoing pressure any higher.

The valve is a mini, the barrel port is .161, ice tube transfer port, pin bolt, no leaks .... I'm heading to the bar ;- )

I wonder what it is ?

wll

[Austringer]

More shims or mod to an RVA. Not to say your 78 is just like mine, but mine is tuned to 840 fps with 18.1 JSB's and can do better if I crank on the RVA. It CAN do it.
Troy

[wll2506]

More shims or mod to an RVA. Not to say your 78 is just like mine, but mine is tuned to 840 fps with 18.1 JSB's and can do better if I crank on the RVA. It CAN do it.
Troy

Thanks Troy,

Ya, I think I will sight this gun in and put maybe three .040 shims in. 1350 psi is quite a bit of outgoing so I very well need more smack as I don't have a RVA..... I will bring this gun into the zone I want !!!

EDIT:

After getting home tonight I added up the shims from what I remember on the '78 .. and it was not .350 like I thought, it was way under that ..... I think Troy is very correct in the shim length, with a outgoing of 1350 needs to be closer to .400+ (~7/16) to really kick it into gear ... maybe that is why troy is getting the speed he is getting and I'm not. I think I was closer to .225, not the 350 like I said. I will defiantly give her another .~.100 of spacer tomorrow and see what happens... I may give the '79 another boost of spacer length too ! I do dread taking these gun apart, for me a royal pain  to get them back and running again ... for me putting the breech on the main tube is the hardest part of this whole conversion ...especially with shims pushing the hammer spring forward !

wll

[nervoustrigger]

Cue in Kevin Nealon as Subliminal Man.

Good luck tomorrow! _{rear velocity adjuster}.  I'm sure you'll get it figured out _{easy adjustment}.  You'll get it running at high velocity and optimal efficiency _{just a twist of a screw}