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Ask Bob / BC by Labradar
« on: January 12, 2018, 08:40:09 AM »
Here is info on BC's when checked via Lab Radar,

I know Bob might be interested.  ;)


Ask Bob / Correct thread sized tap?
« on: December 25, 2017, 01:21:11 PM »

What would be the correct size of tap/die for the ASA threads of a standard air tank?

I have been told several sizes, like 7/8"x14 tpi, 13/16" x 14 ttpi etc,
the thread measurements of the type of threads I have are, .623 to .628 dia x 14 tpi.

Thank you,

PCP, C02, and Helium Powered Airguns / Ham 850 Mag AR
« on: December 19, 2017, 02:57:50 PM »
I can't seem to find the correct answer to my problem,
A little history,

The neighbor HAD a Ham 850, 17 caliber AR, OEM stock, (He bought it new, 7+ yrs ago).
It was sitting in the corner of his shop,
I really don't care for this caliber, but will try it out, I prefer 22 cal.
He made the comment that, "It's yours, for $100", (he knows, I am into guns etc). LOL
He also told me the bolt didn't work right, before I bought it. He stated, that he has shot it less than 1 cylinder thru it,
and then it locked up, bolt don't or won't close, etc.  :o (bolt moves a little back and forth).

So, being the Idiot that can't resist a gun, It followed me home and put into the "needs work rack",
right now it is 5* inside the unheated shop, too COLD for me be inside for very long..

Being new to AR arena, and knowing nothing about Ham 850 AR, 17 cal etc,
I have 50+ 88/90g cylinders, so that end is taken care of etc.
I'll have to get a couple of mags, it didn't come with any, the owner that he has a couple mags, ammo etc, just has to find it all.

I have not had much luck searching the forums so far, on this make and model etc.

Since, I can not get the bolt to operate in the full range, at this time I am unsure what's in the bbl,
It feels like something is jammed in or around the bolt, the bolt only moves around 1/4" or so.

Being a new (to me rifle), I will completely dismantle, check and clean/lube the required parts,
along with adjusting the trigger to suit me, before I shoot it.

Question for the guys that own or have used a Ham 850 Mag AR.

This AR has a cyl installed and can't be turned etc, so I believe that that there is pressure still present,
I can NOT operate the bolt more than 1/4", to confirm this or deny, or see if this AR has a pellet in the chamber etc,
and the safety dose not feel like it's working right.

Can I safety remove/dismantle this AR, to find out if pressure is still present?

I know nothing about this AR and IT'S inter workings etc.
I finally found a diagram of it's internal workings etc, but no other info was given.

I don't need a Kaboom......


Airgun Guild Forum Announcements / PB Fix
« on: October 23, 2017, 07:01:15 PM »

Thank you for the Photo Bucket fix,  8)

Worked like champ,
Now I have a whole bunch of back posts to read,
so I can see the info talked about etc.


Ask Bob / SSG ?
« on: October 18, 2017, 02:09:16 PM »
To quote the info your a posted in the above SSG main Post of yours,

"The idea behind the "Stopping Spring Guide", or SSG is quite simple....
It is to provide a gap between the hammer spring and the hammer, along with preload on that spring,
so that the rebounding hammer cannot recompress the spring when thrown back by the closing valve...."

Question for you,
The above post info for standard setup, meaning close to/or using OEM springs etc?

What would happen, if I wanted to use a very light spring, (ball point spring etc) on the valve stem,
ahead of the normal spring setting place, meaning hammer side of the valve?

Would I need a lighter hammer spring, than OEM, to balance very thing out,
by going to this lighter spring on the valve stem, along with a lighter hammer weight etc.

I am drawing up a SSG for the 79, 22 cal, for use with Co2/Hpa using a 13/3000 psi set to 1100 psi output, all OEM spec's),
this SSG will be centered in the psi cap etc.

My rationalization of this is, (what little I know)> OEM = Heavy hammer/ springs thru out, hammer/valve spring etc,
Lighter valve spring = lighter hammer, valve springs, along with careful tuning etc, for each fuel type,
being Co2 > summer time playing around, > winter time Hpa = hunting time..

Your thoughts/suggestions?


Ask Bob / TP hole alignment ?
« on: October 10, 2017, 02:50:24 PM »

I am sure you have the answer to this question,  ;) and I think I know the answer, they should be vertically aligned,
as close as possible.......

I have been looking at and measuring the TP holes, from the valve, thru the psi tube and into the new repeater breech.

I have an alignment problem, I think,
There is over .062" differences between these 3 spots,
the exhaust hole in the valve, to hole in the psi tube, is off set right (muzzle end) at the front edge of the psi tube diameter hole,
the valve hole diameter is .130", and offset by .062", from being roughly centered, in the psi tube hole.

This hole on the psi tube is roughly centered vertically with the hole in the breech, offset about .025"+,
to the rear of the breech TP hole etc.

A rough diagram would look like this, l l - hole in breech
                                                       \ \ -  hole in psi tube
                                                        l  l - hole in valve

I believe that this misalignment is causing my leaking between the valve and breech etc,
that I can't get sealed, yet.

By doing some careful measuring,
I am thinking, that I can remove the valve and blocking ring, lathe off the excess length of the blocking ring,
which will move the TP hole of the valve, back to the needed distance, for better alignment.

Then remove the internals of the valve, drill/tap and plug the OEM valve hole TP hole/valve locking screw hole,
then redrill the valve TP hole to get better straighter alignment thru the 3 holes,
after rotating the valve 90* and tap/drill the locking screw hole for the psi tube, in the valve,
which will move the TP hole moved approx .062" to the rear for alignment between these holes etc.

I have a new OEM valve, (never installed), the TP hole in this valve is .185" diameter??,
I have not checked the alignment of the TP hole thru the psi tube,
as per your info, the TP holes should be .165" to .170 max.

Or would I be better off lathing/making a new valve with all the holes in the correct alignment and locations etc.

This QB AR is tuning into a project I was not expecting,  LOL.

But I am learning......


The Garage / Am I thinking right?
« on: October 08, 2017, 12:07:43 PM »
I am short on experience here, so I am requesting some help on chambering a new bbl of my QB 79,22 cal.
I am starting from scratch on this bbl. I am pencil whipping a diagram to machine too,   :-\

Please refer to this diagram on post #16, this diagram is close to what I want to do, THANKS Bob..;u=1665;area=showposts;sa=topics;start=15

Here is the info I am working with, taken from the repeater breech/pin bolt/bbl measurements,etc
in reference to the above diagram.

The starting port hole diameter, will be .140" dia, (OEM) and may be opened up to .170" diameter later,
(depending on what the results of testing revels etc), and it has to be .280" (hole center) from the end of the bbl,
this diameter is allowing for the port hole to be enlarged to .170" (this length dimension can't be changed) etc,

The bolt pin pushes the pellet base (inside of the skirt base) into the bbl about .550",

I want to use the 2nd diagram and start the lead angle, just ahead of the port hole edge,
and I hope the longest skirt depth should end up just ahead of the edge of the lip of the lead, and port hole edge.

Or should I use the first drawing diagram, which would be the easiest, as long as the skirt edge is past the port hole edge,

Here are the measurements of the DEPTH of pellet skirts,
Inside depth of skirt, (from the bottom edge of the skirt), with .092 pin diameter, of the repeater bolt.

Benjamin Super Point =============----.052"
JSB Match Exact Jumbo Monster Diabolo==----.058"
JSB Match Ultra Shock Heavy Diabolo====---.064"
JSB Match Exact Jumbo Heavy Diabolo ===---.065"
Skenco Ultrashock Hollow Point========---.072"
Benjamin Hollow Point =============---.076"
Crosman Premier HP ==============---.084"
Benjamin Pointed Expanding =========---.094"
Benjamin Domed Magnum ==========----.096"
Crosman Premier Piranha ===========---.098
JSB Match Diabolo Straton Jumbo ======---.100"
Kodiak Tapered Dome=============----.108"
H&N Baracuda Match =============----.108"=5.51 Head Dia
JSB Match Exact Jumbo Diabolo =======---.112"
H&N Baracuda Match==============---.112"=5.53 Head Dia
Gamo Red Fire =================----.114"
Skenco Newboy Hollow Point =========---.136"
H&N Field target Trophy ============---.142"=5.54 Head Dia
Skenco Newboy Junior=============----.144"
H&N Field Target Trophy============----.154"=5.55 Head Dia
Ruger Superpoint================----.170"
Gamo Platinum==================---.200"

Shortest Base depth = .052"
Longest Base depth = .200"
Difference of .148" in skirt depth.

Any help would be greatly appreciated.

Thank you,

Ask Bob / Spring weight?
« on: September 23, 2017, 08:40:46 AM »
What is the poppet valve compression spring weight rating on a OEM QB -79 valve?

I am sitting here with a brand new 79 valve and have a WILD out of the box Idea brewing.

While checking this valve out,
I find that the valve seating base/area is a raised conical brass ring, instead of flat faced,
that sets inside of a recessed flat type "O" ring of the poppet valve face, (sealing area).

Should I build it the same as the OEM valve seat, or change to a flat faced seat?
I plan on making a Delrin valve set/poppet for the upcoming mod build, ($200 Ninja build).

If a spring weight was say, 17#'s in compression form (pushing), during hammer stroke of 1/8 to 3/16" movement,
and you changed the spring to a lifting force of 17 #'s, (after the compression of the hammer stroke stroke),
the spring would lift the valve stem, by force) etc, would it work the same?

I think, I found springs that would work for this out of the box Idea I have.


Ask Bob / I don't know what to expect?
« on: September 14, 2017, 05:42:27 PM »
Hi Bob

In you opinion, (you are the one with the experience/training in these arena's)  ;), I am still learning the ropes etc.
This is what I am wanting to do, with my QB-79, 22 cal, using dual fuels, set up for summer/winter use etc,
out to 25/50 yds max.

I have a couple of 4 oz bottles (water volume), I want to set up for a small Hpa compact lite hunting rifle etc,
(I believe these are Co2 bottles, 2k psi values), and I want to run Ninja reg Hpa, around the 1200/1500 psi levels,
while testing for the most accurate pellet, after the mods to show the best results,
I have the funds set aside for a Ninja 13ci/3000 bottle, if needed.

I plan on putting on/off valves with psi gages on these bottles, for quick changing etc.
(Keep one filled and 1 on the rifle etc).

What would you expect, your best SWAG, for the results, I realize that every AR is different etc,
I plan on following your $200 Ninja build, for the mods, and hope to add a SSG, to the package,
I am generally asking about the out come......... worth the time/trouble??

What could I expect from this combo, as for performance,
and what Ninja reg would you suggest for these bottles?

I greatly appreciate your thoughts, suggestion or Ideas, good, bad or other wise.

Thank you,

This is a new post for several questions that were being discussed in "the next Big thing in PCP's.

The following info is what I have been playing with, for the .172"/.224" Bullets and .177"/.220" Pellets etc.

I don't know the barrel Bore cross sectional area for the 17/22 cal pellet rifles is, so my calculations are off,
as I know the 22 cal pellet and .177 pellet rifle bore area is smaller, than RF/CF bbl Bore X sectional bbl areas/spec's etc.

I used .222" Bore X sectional of the 22 LR RF bbl, of .037293 sq inches.

The .224" CF Bore X sectional barrel area is .03889 sq inches,
and the .172" CF Bore X sectional barrel area is .022859 sq inches.

I hope that Bob will show the correct spec's etc, as he is the AR GURU.  ;D  LOL
As I am still in the 1st grade.  ;)

I had a choice of which Shot Start (initiation) pressure to use, which is the force required to start the pull out and engraving of the bullet,
so I will post both of the start PSI of "O" PSI and 146 PSI, for both the Bullet and Pellet choices posted.

I used a 3000 psi as Max psi used for all calculations in both caliber examples.

Here is what I came up with for the following Bullets and pellets,
I kept the same standards thru out, ie,
24" bbl length, 3000 psi for pressure,
.220 cal bbl Bore X sectional area of .037293 sq inches, for .220" cal pellets,
.224" CF bbl Bore X sectional barrel area is .03889 sq inches, for .224" Bullets
.172 CF  bbl Bore X sectional area of .022859 sq inches, both pellets and bullets.

.172 cal bullet, 20 gr bullet, with a BC of .185 and SD of .097 at of 1000+ fps,
.224 cal bullet, 35 gr bullet, with a BC of .109 and SD of .100 at 1000+ fps,

.220" cal,  29gr Eun Jin Pellet, 24" bbl @ 3000psi, "O" start psi, with a BC of .xxx and SD of .xxx
start ===@ 5" bbl travel==10" bbl travel=15" bbl travel===20" bbl travel===24"
870 fps = 845 fps ======804 fps ====745 fps =======622 fps======0 fps
3000 psi=1058 psi =====493 psi ==== 309 psi ======= 220 psi =====170 psi

Same as above with 146 psi start
856 fps ==831 fps ======791 fps ====713 fps========616 fps =======0 fps
3000 psi ==1006 psi =====477 psi ====299 psi ========215 psi ======164 psi

35 gr VMax .224 Bullet, 24" bbl, @ 3000psi, O start psi, with a BC of .109 and SD of .100
start ===@ 5" bbl travel==10" bbl travel=15" bbl travel===20" bbl travel===24"
870 fps = 845 fps ======804 fps ====745 fps =======622 fps======0 fps
3000 psi=1058 psi =====493 psi ==== 309 psi ======= 220 psi =====170 psi

Same as above with 146 psi start
799 fps ===773 fps ======739 fps ====687 fps========576 fps =======0 fps
3000 psi ==1006 psi =====984 psi ====464 psi ========281 psi ======159 psi

These are SWAG's,
as I am not sure I have the calculator set up right, for PSI values x distance etc.

I will post the 17 pellet/bullet info later, along with the friction reduction coating of bullets/pellets etc.

Thoughts, suggestions or Ideas?


General Airgun Forum Discussion / Cleaning your AR
« on: June 25, 2017, 04:42:16 PM »
Ok Guys,

I thought, I would clean my QB 79 again,
it now has 1-1/2 cans of pellets thru it,
and started on it's second cyl of Co2 etc.

I can see pellets doing the Hoochy Choochy corkscrew when shot now,
and never seen that when the bbl was clean, so it probably needs a good cleaning.

Ran into a problem when scope mounted,
if using a rod, you can only clean up to the bottom bbl port,
without dumping any gunk into the TP hole etc.

Don't sound like a good Idea, IMHO.

How do you clean from the breach to the bbl ?  :-\

I am not going to tear down and remove the bbl just to clean it.  >:(
I figure out another way to get it done.

I thought of a Bore snake, but don't know it the drop weight/brush's are small enough,
to get past the very short distance from the bolt nose/chamber etc.

Thoughts/suggestion or Idea's?


PCP, C02, and Helium Powered Airguns / Is it safe??
« on: June 23, 2017, 07:45:36 PM »

Is it safe to remove the action from a QB 79 stock, when there is a filled cylinder attached?

I need to do some temp adjusting of this trigger, it it driving me NUTS!!!!!!



I need some help to accomplish what I want to do, if reasonable and safely.
Here is some info, I want to accomplish, if possible,

I have a brand new OTB QB 79, 22 caliber, scoped with a 4x14x44 mm ( Mueller APT), running Co2  now,
with 88/90 gram cylinders and with HPA/reg in the future, using the smallest bottle to provide, 25-50 shots,
the average shot string runs are,

14.3 gr CPHP pellets
Temp 85* >
Shot over my Magnet V-3 chrono
H= 585 fps
L= 576
A= 579
SD =2.6

Shot over my Oehler 32 chrono
H= 585 fps
L = 568
A= 577
SD = 2.6  .

This QB has not been modded yet, but soon will be.  ;)
I want, (if possible) to have the best accuracy (with the correct pellets, after testing), out to 50 yds,
with the highest FPS possible with both fuel types while hunting small game and pesting birds.

I have been haunting several different sites,
and read about a this rear adjustment thingy that controls the power of the valve spring etc,
I can't find the site with this info, IIRR, I believe that Bob posted the info, but not sure etc.

My question is,
Would this valve adjustment thingy, be advisable/help for tuning my QB when using both fuel types,
with what I want to accomplish for both fuel types with the best accuracy and FPS etc ??

I will be running Co2 in the summer, and HPA in the winter times.

I would greatly appreciate any and all info possible, on reaching my goal for this AR.

Thank you,


PCP, C02, and Helium Powered Airguns / Can it be safely done?
« on: June 21, 2017, 12:49:57 PM »

Being new to AR's, Co2/Hpa etc,
I have a question, that has been floating around my head.

I have 55+ cylinders of Co2 in the 88 & 90 gram sizes,
I have a Co2 bottle that came with the QB 79 package,
it is a 9oz and rated for 1800 psi.

Can some of these cylinders be used to fill this 9 oz, Co2 bottle,
meaning transferring the co2 into the bigger bottle?

If it can be done SAFELY, how would it be accomplished?

Or would it be better just to use each cylinder, as needed?

So far I have over 250+ shots from the first cyl, from my stock QB 22 caliber, and it still has co2 left,
I don't know how much co2 is left as there is no gauges to check etc.

For me, it's a 200 mile drive for any type of refilling Co2 or HPA,
I will have a hand pump for filling, to get by,
until the funds in the Rat Hole are enough to get a compressor for refilling etc.

Thoughts, suggestions?


Welcome to the Airgun Guild Forum - New Members / Hello all
« on: June 19, 2017, 10:52:44 AM »
From an Old guy,
New here and to PCP Air Guns.
First AG was a 1960's model Sheridan 5 mm, (bought new),
that I used until it finally wore out, with not holding air any more,
many ground & tree squirrels, rabbits, pest birds and several coyotes,
were laid to rest with it's mighty power.
Just bought a QB 79, 22 cal,
looking for articles, info/post dealing with modding it, for the best accuracy/ballistics etc,
using dual powered fuels, with Co2 for summer time pesting and HPA for winter time hunting.

Then I'll start over with an Airforce Condor 22 cal, pending final payment.

Hoping to learn more about AR's, to merge with 62+ yrs of the PB shooting, building and enjoying them,
avid Wildcatter, with 17 and 22 calibers being the favorites.

22 yrs ADC work, 36 yrs LE, retired and loving it.


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