Beeman Chief - Merry Christmas to Me !!!

[SpiralGroove]

Merry Christmas Bob,
You're lucky to have a wife who understands your need to tinker .

Utilizing the OEM-RVA, tuning the trigger slightly and notching the receiver for cocking "On-Open" .............. I can tell you're gonna tear into that valve in no time.  This gun represents almost the same tune as your now famous $200 QB79 project.

Since you have the 2,000 psi/148cc limits, you likely won't regulate as is.  Adding a bottle would make the Chief high/low-brid QB 79, so I know you're not going that route.

It seems like increasing/reinforcing the air tube to make 200 bar would be a good option to increase a power shot count.  Additionally, making a maxi-valve with front facing, retaining spring would increase shot count/efficiency.  you could then (maybe) get 30 to 40 high powered shots at < = 4% ES.

This gun is a hunter ......................... not a target gun.

[USAFANG6799]

Bob,

By doing the in depth review on the Chief you've given me my Christmas gift :-) I'm going to study this review to the 'T' because I bought a Chief 22 caliber about 6 months ago. Despite some of the short coming that's inherent with it and you touched on I really like my Chief.
I put a Rocker1 moderator on it to quite it down, worked on the trigger and played around with EXTERNAL PRELOAD ADJUSTMENT. I must say that overall I'm very satisfied it. The only small source of irritation is that it does not hold air as long as my DISCO and Marauder.

Looking forward to your continued review.

Matt

[rsterne]

Kirk, since we don't know what the tube is made of, I would stay pretty much with the factory pressure recommendation.... The tube is 26 mm OD x 2 mm wall, and if we assume basic mild steel (something like low-carbon 1006) we hit a 3.5:1 safety margin to failure at only 2100 psi.... By using a CrMoly tube with a 1" OD x 0.065" wall we could easily fill to 3000 psi, PROVIDING we changed the pretty wimpy looking valve screws, and checked everything else over.... but you're pretty much talking starting from scratch.... This gun at 2000 psi is just like a QB at 1800, in terms of likely safety margins.... and assuming both are cheap, low-carbon steel....

Anyways, a half hour of work makes a WORLD of diference.... Here are the trigger to sear surfaces.... The short surfaces are the "active" ones that affect the feel and smoothness of the trigger pull.... the longer, curved ones slide over each other after the trigger breaks....



and here are the surfaces that contact the hammer.... The short one holds it back and the long one contacts during cocking....



I expect a huge difference, time to put it together, and install the lighter spring and 2nd stage plunger.... back soon....

Bob

[Hoosier Daddy]

Good stuff Bob, you got me on pins and needles!

[Ribbonstone]

Your pictures cleared up some earlier posts.

The new ones have a different real end cap.  First ones don't have an adjuster, have only the small diameter hole for the  degasser.






This was the orginal full-length striker spring (and it's sharp end coil).



And the same spring cut (and later shimmed back up). Can see the discoloration of the last coil were I made a dead-end:



As for why it's a little faster..haven't a clue.  25fps is bascially "nuthin"...not sure what they are/were advertized as, but likely somthing much faster than this.

Trigger is a pretty good one for being as simple as it is (and quite easy to get to the parts).   Your polish job/ adjusting the 3 supplied screws whould do "it".  Haven't found shimming the trigger pins to be a help, but maybe some are sloppiwer fits to the pins than others.

I just don't believe that tube is the 136cc's that PA mentions in their ads.  Thinking more like 150-160cc's, which isn't a whole lot of difference....likely only important to efficiency calculations.


Only other things are more-or-less cosmetic.

Put on an LDC (which isn't an option for everyone)
Removed the iron sights.
Moved the barrel band to be inletted inside the stock.
Hit the gold "BEEMAN" lazer cut logo with liquid brown shoe polish (cleaning the stock, leaving the logo readable...but brown rather than gold).

[rsterne]

Actually, Beeman only claim 830 fps in .22 cal, mine does that with the 18.1 gr. pellets (on the first shot).... The degasser on my gun is much larger in diameter than your photo, the threads are 10mm, the rod goes through a hole in the preload adjusting insert....

In order to install the 2nd stage spring plunger I removed the overtravel (middle) adjustment screw, ran a #36 drill through the hole, and re-tapped it 6-32 for the plunger....

Here is the trigger re-assembled.... the first photo shows the trigger at rest, note that I have adjusted the upper screw so that about half of the sear is engaged.... The sear would be rotated clockwise until in contact with the trigger when it is holding back the hammer.... The more the sear is engaged (the further you back out the upper screw) the longer the first stage travel is.... Note the gap between the trigger and the tip of the 2nd stage plunger....



The second photo shows the trigger pulled until it has just contacted the 2nd stage spring plunger.... Only about a third of the previous sear engagement is present.... any slight additional movement of the trigger will fire the gun.... The position of the 2nd stage plunger controls how much sear is engaged when you feel the increase in resistance.... The adjustment is very sensitive, make sure you have enough engagement that the trigger remains safe at this point....



I have replaced the spring with a much lighter one, and the pull weight changes noticeably when the trigger touches the plunger.... I will make final adjustments after installation....

Bob

[SpiralGroove]

Kirk, since we don't know what the tube is made of, I would stay pretty much with the factory pressure recommendation.... The tube is 26 mm OD x 2 mm wall, and if we assume basic mild steel (something like low-carbon 1006) we hit a 3.5:1 safety margin to failure at only 2100 psi.... By using a CrMoly tube with a 1" OD x 0.065" wall we could easily fill to 3000 psi, PROVIDING we changed the pretty wimpy looking valve screws, and checked everything else over.... but you're pretty much talking starting from scratch.... This gun at 2000 psi is just like a QB at 1800, in terms of likely safety margins.... and assuming both are cheap, low-carbon steel....

Bob

Yeah Bob,
I forgot those Ninja tanks being regulated provide air at a (safe) set-point between 850/1500 psi, hence the air cylinder/valve is (hopefully) never exposed to anything above that level.  The burst disk provides some safety.
 
Boy those Ninja tanks sure solved/removed many problems.

With the Chief, I guess the valve, hammer weight and (RVA) spring need to be balanced well together, increasing efficiency enough to get (maybe) 25 strong shots < 4% ES.

Have fun

[Ribbonstone]

Considering all that Bob has written of/done...am wondering what his goal might be. NO real mods will earn 25shots/25 foot pounds (or more foot pounds with the really heavy weight .22's at upper 600's  speeds).


Am thinking this won't get the powderpuff treatment I've done, leaving well enough alone at 25X25.

[SpiralGroove]

Hey Bob,
One last thing (not to be negative)
Other than appearance/some safety issues (related to bumping the tank) ->
I can't think of why one would choose a tuned Chief over a QB79 HPA?

[Gertrude]

In order to install the 2nd stage spring plunger I removed the overtravel (middle) adjustment screw, ran a #36 drill through the hole, and re-tapped it 6-32 for the plunger....

Here is the trigger re-assembled.... .... Note the gap between the trigger and the tip of the 2nd stage plunger....

Bob

Bob,
Maybe I missed it, but Can you give us a little more details on the plunger itself ?
 Is it a "Take-off" of something ?
Where to do buy this tiny spring plunger ?
 What is the correct length ?
 Do they come in different spring tensions ?

Thanks

[Ribbonstone]

HAve both.


How about this:

45 pumps to refill...25 shots at 25 foot pounds.


150 pumps to refill...88 shots at 25 foot pounds.

  You know...it works out pretty even.

[SpiralGroove]

Have both.
How about this:
- 45 pumps to refill...25 shots at 25 foot pounds.
- 150 pumps to refill...88 shots at 25 foot pounds.
You know...it works out pretty even.

So, if U have a tank ............ QB79HPA is the winner -> No pumps, more shots.
If you pump and want more shots, QB79HPA is the winner
If you pump and want 25 shots, Chief could be the winner
If you pump and want 25 shots, QB79 would be the same if tank already filled to 100 bar. 45/50 pumps should get U 25 regulated shots.

The problem with the QB79 is they're harder to come by now and more costly than previously.
Don't get me wrong, very much like the Chief, but already have 4 QBHPA's and trying to find a sig./diff.

[WesBob]

Just wanted to say congrats Bob, and that I'm really excited to follow this thread. Thanks for sharing your progress! It'll be great to see what kind of accuracy and shot count you get when finished tuning ☺️. I really like the look of these chiefs.

[rsterne]

Well, trigger mods always seem to need tweaking.... The lighter spring I used was too light, so I went back to the original one, at reduced preload.... This produced an "acceptable" trigger, but I really need a spring in between the two.... Using a longer, weaker spring with increased preload will give a more constant trigger pull over the 1st stage travel.... which is what I wanted.... but the light spring I had was just too light....

I noticed one other thing I'm not crazy about, and I have seen this before with QB triggers.... When you lighten the trigger spring, the sear has a tendency to not reset if you pull the trigger through the first stage and then release it without firing the gun.... The reason is that the load from the hammer is too great to overcome the friction between the sear and the trigger.... The term for this is "balk firing", and it is VERY common in Springers, where you usually have to re-cock the gun to reset the sear.... I can't tell you if the stock Chief trigger was doing this or not, I didn't check for it.... but the surfaces were so rough I would bet on it, even with the stiff spring.... It is something to keep in mind, if you start to take a shot and then change your mind, you can leave the sear "hanging" on the verge of firing.... The way to clear it is to recock the gun, by pulling the bolt back all the way to take the hammer load off the sear.... It is a good practice to get into, and especially necessary if your sear doesn't reset when you partially pull the trigger and then back off on the shot....

While I had the gun apart, I pulled the barrel and receiver and checked out the ports.... They are pretty small, and all the same size.... The barrel port, receiver port and valve exhaust port are all 3.5mm (0.138"), and the flat O-ring type seal between the valve and receiver is also the same ID.... In addition, the valve in my gun is slid back a bit, so the exhaust port is partially covered by the seal, restricting it even further.... That 25 fps that Ribbon had over my gun could be right there....  .... The valve has slid back because the holes in the tube for the valve screws are a bit larger than the screw heads.... With 2000 psi of pressure pushing back on the valve with 1178 lbs. of force, the valve slides back until the screw heads are tight against the back of the holes, and the exhaust port, that should have lined up with the seal and receiver port, is back from where it should be.... A seal with an oversized hole would probably help, or if, as I am, you plan to enlarge the ports, you can carve more out of the front of the exhaust port than the back, to re-center the port relative to the hole in the tube and the ports in the receiver and barrel....

Anyways, with the gun back together, I tethered it to a regulator set to 1800 psi and proceeded to go through the entire range of preload adjustment, shooting five JSB 18.1 gr. Heavies at each turn of preload and recording the average.... The results are in the chart below....



This is a classic curve, with a "plateau" where additional preload adds NO velocity and only wastes air.... a "knee" where the velocity starts to drop, and then a "downslope" where every time you reduce the preload the velocity drops.... Stock preload on my gun was 4 turns out, right at the beginning of the plateau.... Therefore adding more preload does nothing but make the gun louder and waste more air.... On the other hand, the knee of the curve is at 5-6 turns out, and that is a good place to experiment.... Less preload than that looses more velocity.... Now this was at 1800 psi, at the 2000 psi fill pressure, the entire curve would move up (faster) and to the left (more preload).... That 4 turns out stock setting is probably right at the top of the knee at 2000 psi.... Anyways, now that I knew where the knee was, I could try reducing the preload to see what happened to the shot strings.... Here are the results....



Only shots within 4% of the maximum velocity are shown on this chart.... The red string is from yesterday, but I omitted the shots below that 96% velocity point, leaving only 8 shots within a 4% ES, the velocity dropping with every shot.... pretty dismal the way it came from the factory.... This is what happens when you tune a gun on the plateau.... I reduced the preload 2 more turns, and shot the string in black at 6 turns out.... The starting velocity was only 742 fps, it wasn't until shot #5 that the velocity climbed within 4% of the 794 fps peak (which is why the first 4 shots have been omitted from the black line).... I got 22 shots, ending at 1400 psi, so the usable string was 18 shots within a 4% ES, starting at 1900 and ending at 1400.... I increased the preload a turn, to 5 turns out, and shot another string, recorded above in blue.... This is about as good as it gets for my 2000 psi fill.... The first shot was within my desired 4% ES, the string peaked at 809 fps, and I got 16 shots with the string ending at 1500 psi.... Here is the summary of these 3 strings.... all of which were shot with JSB 18.1 gr. Heavies, from a 2000 psi fill....

4 turns out - 8 shots, average 814 fps (26.6 FPE) @ 0.98 FPE/CI
5 turns out - 16 shots, average 794 fps (25.4 FPE) @ 1.31 FPE/CI
6 turns out - 18 shots, average 779 fps (24.4 FPE) @ 1.41 FPE/CI (1900 psi usable fill)

So, there is the key to tuning your stock Beeman Chief.... Try backing out the preload adjuster a turn or so, to get a proper bell-curve and double your usable shot count, with a big increase in efficiency....

Bob

[Nvreloader]

Ron
Not Bob, he is better looking, 
Can be found on Amazon and numerous machinery places etc.

Those screws are called "spring plungers" or "Ball plungers",
they come in various rates/sizes,
the light weight ones are around .50 to 1.50 lbs,
and the heavy run from .50 to 3.50 lbs, they also come in metric sizes also,

Screw sizes run from 4-48 tpi (smallest) to 5/8-11 tpi, most common sizes, long and short lengths.

HTH,

Tia,
Don

In order to install the 2nd stage spring plunger I removed the overtravel (middle) adjustment screw, ran a #36 drill through the hole, and re-tapped it 6-32 for the plunger....

Here is the trigger re-assembled.... .... Note the gap between the trigger and the tip of the 2nd stage plunger....

Bob

Bob,
Maybe I missed it, but Can you give us a little more details on the plunger itself ?
 Is it a "Take-off" of something ?
Where to do buy this tiny spring plunger ?
 What is the correct length ?
 Do they come in different spring tensions ?

Thanks

[rsterne]

My goal?.... I dunno, I haven't really set on yet, I'm just beginning to understand the gun.... Ribbon, you are clearly way ahead of me on shot count, I'm only at 16-18 shots within a 4% ES at 25 FPE.... I'm not sure why the usable shot string peters out at only 1500 psi, leaving only a 500 psi usable pressure range.... My stock Discovery, with the same pellets, got 25 shots at almost 23 FPE, from 2000 psi down to 1200.... With a bit more preload to get that to 25 FPE, the shot count dropped to about 16 shots, ending at about 1400 psi, pretty much like the Chief.... The extra reservoir size it has goes out the shorter barrel....

My usual tendency is to see how much power I can get, within reason, and then back off a bit to shoot a specific pellet weight at a usable shot count.... I am hoping to be able to use 25 gr. pellets at about 50 FPE.... but unless I can get more than a 500 psi usable range of pressure the shot count will be dismal....

Kirk, as you know, I love my QB79 bottle gun.... It is set up for a ton of shots at 25 FPE with 15.9 gr. pellets at 850 fps.... and is pretty hard to beat.... I don't need another one at that power level, and the QB79 is a poor choice for mad-dog power.... Maybe the Chief will find a niche there, I don't yet know....

The plunger I used is similar to this one from McMaster Carr.... https://www.mcmaster.com/#8495a11/=1auyle4

Bob

[Ribbonstone]

 BOB:

50 foot pounds might be a touch hard to get to....but if you eat the elephant in bites, sooner or later you'll likely get there for a few shots.  Not sure how much original Chief parts would be left, and not real happy with safely in beefing up the retention screws and bosting pressure (although I'm all for changing the screws to somehting a little more confidence inspiring than phillips heads).

Am certain that 35 foot pounds is in there.  Never shot a full string, just a test (with a non-Chief barrel)....but (as you know), moving air and moving water are alike in some ways: bigger diameter holes move volume faster than smaller diamter holes.

Top barrel is from the Chief.  Bottom barrel from a QB.  They aren't quite swap-outs, but so close that the only real difference in the end is the length of the loadging platform.

TWOSTAGE vs ONE STAGE:

Really...what difference does it make?  Don't you "not so good up the slack" and stay poised within an ounce or two of sear break either way?


SpiralGroove:

 Do keep two (the 5mm  3rd soon to return to HPA) full time HPA QB's.  Lots of shots are what they do best....so I set them up for lots of shots per fill.  Kept them to 850psi outputs, 12 foot pounds/170 shots for the .177 AR2078 and 13 foot pounds 200 shots for the .22QB79 carbine.

They are still air hogs.  Really not terribly inefficient, but really just middle-of-the road efficient.  Guess the regulator does work...work comes from the gas being used?

Also kept an MrodAir PCP pistol/carbine converted.  It's not an air hog.


 But at the same energy it's air use is the same as modded M-Rod.  Mot more shots at 45-50 than the p-rods 24-25 shots, but 1/2 the air use with the P-Rod for the same energy.  Overall, it's a little "better" than the P-Rod as it manages to do that with a shorter barrel.

With a fill tank, who cares about efficiency?  Worst case, you go get your tank refilled more often.  Can be an absolute air-pig and all it costs is a few $ in gas money.

As for accuracy, I've yet to be able to demonstrate a difference between 1 1/4% varation (what normally will happen with out-the-tin good pellets) and 4% varation (what I keep the shot counts of non-regulated PCPs to.  YES....I have swaped-tops with the QB's from regulated to an un-regulated 3K HPA tube. 
Barrels that shot better HPA also shot better PCP.....is a difference between barrels, but not the same barrels on different tubes.

Yeah...logically there should be a difference....just like there should be a difference between pellets sorted out to the 1/10th grain vs the 3/10ths grain...of to the 1/10000ths head size vs the 3 /10000th head size.  Whatever the difference is, it gets lost in all the other varaibles of actually shooting.


So I will strike a deal.

Not too long and I will get to my 2nd (and likely last) retirement.  Once my age begines with a "7" I'll go back to tanks....but likely (due to an industrial supply place close at hand) a big 6K Nitrogen tank.

They I won't give a rat'stookis what the efficiency is, as it's not my energy going in vs energy out, and (although costly) they'll come out and truck , remove the old one, deliver the 6K replacement.

[rsterne]

You're probably right.... 50 FPE at only 2000 psi in .22 cal is a pretty tall order, especially with only a 21" barrel to play with.... A better goal might be to drive the 18.1 gr. Heavies in the mid 900s (36ish FPE).... I hit 52 FPE with a modded Disco with 28 gr. EunJins right at 2000 psi, but that was the peak of a 10-shot bell-curve starting at 2500 (10-32 screws in the valve), an option I don't have with the Chief (unless somebody convinces me the tube isn't the cheapest steel you can get).... More recently, I got to 75 FPE with my regulated Disco Double using a 2000 psi setpoint and 34 gr. Beasts.... It was able to hit 60 FPE with the 25.4 gr. Monsters at only 1800 psi.... but that gun sported a 28" barrel....

Still, I won't know what the Chief can do until I try, right?.... I can always shoot for the moon and then settle for a high orbit.... 

Bob

[Ribbonstone]

Think 35-36 foot pounds for 20 shots is do-able without too much serious "revision" of the "guts"...maybe...but with a revision of the valve, solving of the limited pressure range, it you could work you way to 20 shots at 40 foot pounds.

Which isn't outrageous....didn't we try for 20X20 with a FDPCP not all that long ago?

[rsterne]

Today I used the degasser to dump the pressure (works well).... It comes with a 5mm allen key, the same size you need for the velocity adjuster, one tool does both jobs.... I then stripped the gun down completely to examine the valve and porting.... Here is a photo of all the relevant parts in stock form....



The barrel port, receiver port, seal, exhaust port, and even the through hole in the gauge block are ALL the same size, 3.5 mm (0.138")....  The gauge uses straight threads and seals against an O-ring in a 10mm deep blind hole in the gauge block, in similar fashion to the Disco.... There is a screwdriver slot in the front of the gauge block, at right angles to the gauge port, and the hole is the same depth as the side of the slot nearest to the gauge port.... This means that as long as you stay the other side of the slot (even touching it is OK), you will have sufficient material for the O-ring to seal against.... Therefore it should be no problem to open up the gauge port to allow vastly increased flow into the valve....

The inlet hole in the front of the valve is 5 mm (0.197"), and the valve throat is the same.... The valve stem is 3.15mm (I thought it would be 3 mm, but it is actually 1/8").... This means that the valve throat has an area of only 0.0182 sq.in.... which is the equivalent of a hole of 0.152" (3.9 mm).... So, the valve throat is bigger than the rest of the porting, but just barely.... There is quite a bit of room (over 1/8") between the front of the exhaust port and the valve seat, so enlarging the exhaust port, within reason, should be possible without breaking into the back of the valve and ruining it.... Incidently, the probe on the bolt is quite large, at 0.152" (nearly 4 mm), so the area available for flow to the pellet (.22 cal = 5.5 mm) is 0.199 sq.in..... which is the equivalent to a hole of 0.159" (4 mm)....

There is very little volume between the gauge port and valve, they are only about 3/16" apart, so about 2 cc there and another 3 cc inside the valve.... The reservoir, from the back of the fill fitting to the front of the gauge port, is 13-5/8" long x 22 mm (0.866") diameter, and there is about 1 cc additional volume inside the fill fitting.... I would calculate the reservoir volume to be (132 + 1 + 2 + 3) = 138 cc, and will be using that for any future calculations.... Note that this is almost identical to a Disco, and they run the same 2000 psi pressure, so they both have the same volume of air available.... enabling direct shot count comparisons....

The poppet is VERY interesting.... The material is VERY soft, more like a hard rubber (maybe 150D? ) than a Delrin type plastic.... you can dent it with your fingernail.... The back (seat) side is cone shaped, with the sealing surface around the outer edge, and the OD is quite large, at 10.5 mm.... In fact, the back edge is belled out slightly (presumably from contact with the seat) to 10.8 mm (0.425").... There is a clear mark on the back from contact with the seat, and the ID of the sealing perimeter is 9 mm (0.354"), so the seat is larger than that.... A good value to use for calculating the force required to crack the valve would be at least 3/8", so at 2000 psi that would require 220 lbs., and with the soft poppet material, that force is applied over a longer distance, increasing the hammer energy required significantly....The valve spring is moderately stiff, and it sits against a brass spacer on the poppet.... I'm not sure if that is to increase the preload (which it does), or to prevent the end of the spring from digging into the soft poppet material.... The front of the poppet forms a spring seat/guide.... Incidently, the ID of the valve is 13mm (0.51"), and there are two O-ring grooves directly over that section, and they are 0.676" diameter.... That leaves only (0.676-0.51)/2 = 0.083" of material supplying strength to the valve body.... so boring out the ID of the valve is not a good idea.... There is just over 1 mm of clearance around the back end of the poppet (between it's OD and the valve ID), which is a total area of 0.0314 sq.in.... While that is larger than any of the other flow passages, it doesn't leave much extra room, being the equivalent of a hole of roughly 0.200" in diameter....

All seals, on the valve, both ends of the gauge block, and on the front fill fitting (not shown) consist of two quite large O-rings (2.5 mm CS).... Now in theory two rings are no better (some say not as good) in providing a seal (because O-rings work better with a large pressure differential across them).... However, it does provide redundancy, in case one is damaged on installation.... and the rear gauge block O-rings and the valve O-rings must slide across the hole in the tube for the gauge.... which if it has any sharp edges makes a dandy cheese-grater (O-ring slicer).... You can bet I will be carefully deburring that hole before reassembly....

One final thing, the three valve locating screws are not very confidence inspiring.... They have Phillips heads, and are only 4 mm x 0.7 mm, and a rather loose fit in the holes in the tube to boot.... I think I will be looking for some better screws....

Bob