Artemis PP-800 /Diana Bandit

[Racing]

This thing about fell into my lap for a song so.. who am i to say no.
Have read up a bit which made me at least a tad wiser. Seeing this is a rather common piece of kit.

This one of course with a broken off bolt handle per usual, where they had drilled through the stock remains of the bolt handle and just shoved an M4 screw through the whole mess. Of course crooked...Of course it was... so scrap bin time.

Got back to the shop n tore it apart. Would say it was all there so the only real complaints were basically twofold.

So to handle issue No1 turned a new bolt handle for it.



Sry about the low Q pic, but you get an idea at least. To spread the loads imposed better i soon realized that the "track" the bolt runs is on 4,7mm width while the thread on the bolt is M4 flat. Thus i made the new bolt handle on them specs, handing that the bolt handle loads now spreads to the probe way more efficient as it uses that shoulder that came as a result of the two varying diameters. Way less unit loading in other words.
Sry to say the actual handle spun on the lathe.. will have to make a new one ( read - outta steel) seeing the damage to the knurling.

Anyways.
The actual puff is rather neat IMO. Rather specific and to the point me thinks, while ample room for improvement. I was a bit puzzled by how Snowpeak limited the stroke on the poppet for instance - to keep power down i guess.
Less than 1mm worth of "free stroke" (measured it was like 0,8mm). Recut the valve housing so i had like 3.5mm popout on that poppet shank, in other words way more stroke at will.
For the hammer spring i simply turned me a shim to increase preload as a first measure. These two mods alone came to net like shy of 35J/25fpe of muzzle energy out the snout of that rather, after all, limited length pistol barrel.



The actual stock on these things though, itīs nothing short of insanely large! Only real comparsion come to mind is the Desert Eagle pistol and the likes. I truly think theyīre delivered like this for the end user to reshape to fit. Canīt see any other reason as to why...
Beech wood from what i understand but.. yes. The rasps and what not came out in a hurry cause this was just plain silly. So there in the pic, just coarse cut thus far. Finishing will be down the line, of course. Needs more shaping first though.

As much as 35J is decent for such a pistol n i believe iīll modifiy the valve to take a PEEK poppet on a 2mm shank at that. It will no doubt increase performance out the muzzle but truth be told i also think iīm going to redo the entire setup out rear so iīll be able to use a shorter n stiffer spring set on a SSG.
Of course then to be adjustable, where the rear M4 bolt for the breech to the tube comes in.. so need to adress that as it runs straight through the end cap/plug.

The stock moderator in turn contains "the usual" Artemis/Snowpeak setup with a number of cones and pieces of aluminium tubing to keep them apart. Rather many... top of my head that short thing on there contained like 6 or 7 chambers for some reason?
No matter.
Turned a number of more conventional baffles and then wrapped some of that "grille" steel net iīve got laying around onto which i just per usual wrapped some Wettex rag.. indeed. Came to 4 chambers in total and a noise reduction of an easy 50%.
WAY more silent in operation.

Trigger assy in turn.
Here i believe Artemis bummed out TBH. Trigger assy carries 2pcs of M3 allen stop screws. All good, a longer one that threads directly into the trigger blade and then a smaller one that threads into like a tang on the actual trigger blade out rear.
As i adjusted this i came to a point where the sear engagement essentially turned "numb" in as much that as soon as you touch the trigger the gun went off.
Not exactly ideal.
Remedy was simple. I just took that longer M3 out and installed it to the allen key in case with a drop of superglue whereafter i took it to the grinder and cut it the shape of a sharpened pencil.
Issue was that the end of said screw is in essence flat, why after a certain point that flat will keep the sear from "rocking" as it should. By sharpening the screw in case that area on the screw end turned to "nothing" where it meets the sear up, handing that now you could adjust the sear engagement WAY WAY WAY tighter.
If youīve got a PP-800 or Bandit just get this done, difference in trigger is like night n day and whatīs called for is very very simple to pull off.
Next up then the second, way shorter screw that resides on that tang on the trigger blade then...

Here somewhere someone at Artemis made a boo-boo. Point being that as you now adjust sear engagement way tighter the slack between 1st and 2nd stage is set by this small set screw on that tang.
The issue is that for whatever reason Artemis decided on drilling and tap for that screw rather "far in" on that tang, vs the center of the trigger blade. This brings that if you back that screw out completely now the actual tang as a whole will work against the sear bringing way more "arm" into the equation, making for a lighter trigger pull.
So.
I took that screw out and reinstalled it with a drop of blue Loctite (did for both screws actually) and just turned it in enough to NOT protrude any lower than the tang is deep, handing me a way more suitable trigger for pistol use.
In short Artemis should have put that threaded hole WAY further out on the tang to be of any appreciable use. Now itīs kind of just along for the ride to be honest, which is far from bad seeing that beech wood stock and how it fills out your hand. As the trigger blade moves further in from the above it just stands to reason that this hands a smaller "grasp" on the thing, handing way better trigger control.

To my mind at least a pistol for accuracy work should sport a trigger way lighter than most rifles, but.. thatīs just me.

The tank on a mere 40ccīs vs 30+J out the snout?
No. It wonīt amount to many shots, this is true but.. i guess to an extent this can be reasoned as much as intent for the pew.
Where weīre at i get like 5 or 6 shots on target before POI starts to shift.
As i modify the valve to sport a PEEK seal on a 2mm shank power will most likely jump a tad still, and this is where an adjustable SSG comes in iīd say.

Last..although iīm rather used to pistols (been into IPSC once semi hardcore) iīve never really bothered with red dots. Thatīs going to change now, and plans for starters is a simple n cheap one.
That said being fully aware that the cheap ones wonīt take to any abuse what so ever.. but just wanna try it on for size.

In turn of course getting the stock to where i want it as far as shape n finish.

[Racing]

Said n done. Weīre getting somewhere me thinks 



As to if and why theyīre delivered with that absolute behemoth of a stock... no idea. A fact though is that with a few tools and a little patience, the difference in hold n purchase on the gun is like night and day.
To the letter.

The "new" purchase coupled with the trigger work has taken this rather mundane piece of kit to something thatīs actually usable for delicate work even.

Oh. Lest i forget.
Barrel got a trip on the lathe too.

Remains to sight the thing but that said i still give thought to a 2mm shank poppet and what itīd bring to the party.

[naptemp]

Let me know when you get 4 magazines worth of shots with a spread of less than 10%.
I did tune mine for 36 shots (4 mags) in the lower 400s, and I had to use a very finely tuned BStaley mod on mine.

I and like many others consider this to be one of the hardest to tune unregulated airguns.

[avator]

I began with a CP1, took it to level 2 (CP2) then upped it to a PP800 carbine in .177.
Here is the full story if interested.. https://www.gatewaytoairguns.org/GTA/index.php?topic=182687.0

Some folks build for power, some for accuracy and some for efficiency. I'm not much for wringing out every drop of power as much as shot count and accuracy. I also try to achieve a nice bell on the string curve. In this particular gun my goal was reached with a custom cone shaped TP and trimming the hammer spring..  nothing more.

And here are the results.

[avator]

And here it is today with the ATN X-Sight II HD NV scope, Buck Rail silencer, CARM mag and CV Life bipod.
It easily converts to a pistol with the holographic red dot and it all fits in a backpack.

[Racing]

I hear you.
From many an aspects the Stormrider,CP and CR and...never ending story are really just different takes on the same basic hardware.
Like you i ran into a CP-2 a while back, and to be honest all done i came to feel itīs the rifle Snowpeak should really have put in the market.



Only reason i picked it up was that i was bored and it just fell into my lap for like a song. The Co2 bit.. nope. Ainīt happening on my watch.



So. A scarf joint and some seamless high pressure tubing later i had me a CP-2 HPA gun on a 330cc tank. THAT kind of changed the entire deal and all of a sudden the thing became interesting as a carbine.
Why?
Well with that amount of air onboard it changes the entire presentation doesnīt it why i came to tune that thing on the carbine barrel to like 90J/66fpe in 22cal. Due the tank room enough to come back home n tell about it.
One of the features of this "(&#^((&^*" being that it, as youīre aware, was very very light. To the point that at 66fpe it actually jumped around on the table as i fired the thing.
That being said though, to my mind... the perfect "truck gun". Rugged, extremely light, basic to the build - way less things to eff up.. and reasonably powerful.

This PP-800.. to me an entirely different deal.
Got no use for a pistol for pesting TBH why this thing in essence is for handgun training only. As such utmost power is of less concern, however the idea of mine still stems from making things.. effective.

The amount of hammer bounce out of this thing is mind boggling if you ask me.
As such.. i pushed a tad further today.



Yes. A poppet out of PEEK and on a 2mm dia shank. This of course made power out the snout jump, to an even 40J/30fpe.
But.. if not to be used for pesting, whatīs the point?

The point is that through keeping port dimensions on the small side i keep airspeed high. By increasing power of the unit i will most likely reap whatīs there to be had as i get to that SSG.
Idea of mine is for an SSG sporting a rather stiff spring and thus loads of free flight for a very short burst of air and in turn an absolute minimum of hammer bounce (i hope).
Truth be told iīd rather see a mechanical solution to the hammer bounce issue but.. kind of far fetched for a gun as cheap as this PP-800 and the SSG in turn...
Iīll have to move the rearward bolt that keeps the receiver to the main tube. I plan to do this by milling two holes in the side of the receiver and then drill n tap the rear plug for them.
This will rid the unit of the center bolt that in essence is the hinderance for even something as simple as an adjustable HS.
The SSG though, there i want to try out something iīve had in mind for a while and thatīs a collapsable rod setup. Ie; one that fits within the other but keeps absolute movement to a stop at its end. Part of this of course comes down to total throw/stroke on the setup but.. need be i guess you could always make a three piece or four piece unit too?

Anyways.
Still on the stock HS, just shimmed, still on the stock 3.5mm ports the thing is now handing an easy 40J/30fpe using 25.4īs and truth be told seeing the amount of air released i wouldnīt be surprised if power jumped a bit yet just using heavier pills still seeing the after all rather limited barrel length.

[Racing]

You know guys, sitting here thinking.
As you read the following plz be adviced that i keep heavy machinery, know how to swing it and am in turn an engineer from the onset.

The true limiting factor of these units is the lack of air.
There.
Iīve said it.

40ccīs is.. nothing. This got me thinking  (as iīm no newcomer to making my own pressure vessels) along the lines of the now semi fabled Hatsan Jet series pistols. Think of THEM what you will, the idea iīm after here is twin air cylinders.

One of the features of the PP-800 in turn, as it were, is that itīs rather light weight. Very light weight even. What that tells me is the following....

I want to put this cheap trainer together. In essence of no more power than it can be used indoors, so say 15J tops all said (itīs a 22 after all).
Could i make that work for a 40cc storage? I guess, but the more i think about it.. is it really called for? Them mere 40ccīs.
An added pressure vessel that uses the stock bung for the pressure gauge as entry could very well be deviced aīla the Hatsan Jet, just out of steel and while that might sound excessive.. again. The pistol is very light. Even a steel cylinder isnīt all THAT much mass to be honest. Keep the physical limitation in mind here.

Trainer as in something to keep ME up during the cold season, as what i normally shoot are 38 and 45cal revolvers that come in at like 1200-1400 grams fully loaded.

The PP-800 isnīt even CLOSE to them numbers why a steel cylinder added beneath the already existing one might add like 100 to 150 grams, 200 tops, while handing me an additional say 100ccīs. "Hang" it out front by a drop adapter and rearwards vs the trigger guard via two turned simple rings brazed together - keeping a stop screw or two.
The more i think along these lines... ?

Itīs no doubt an option. With a PP setup using the stock ports (or even smaller for that matter need be) with a fair amount of poppet stroke n hammer which in turn will be limited by the hammer spring "smack" due a SSG. Ie; what weīre talking here is short fast bursts of air seeing the properties of the hammer assy setup in mind.

Believe iīll scrounge some steel tubing up tomorrow and see what diameter, lengths and weights all this would bring.
If it keeps the entire package under 1200 grams weīre good as i regard it.

[Racing]

Right.
Letīs see where this takes me.
Total this will end up on 160ccīs.

[naptemp]

Right.
Letīs see where this takes me.
Total this will end up on 160ccīs.

You attached another air tube.
It looks like a Hatsan Jet 2.

I wish I had your skills and tools and time and ....

[louigi600]

So. A scarf joint and some seamless high pressure tubing later i had me a CP-2 HPA gun on a 330cc tank. THAT kind of changed the entire deal and all of a sudden the thing became interesting as a carbine.

Did you turn a new valve assembly ? or you used the original one and turned some o-ring grooves in it ? (along with some bushing for the 2mm valve shaft)
Is the valve assembly held in place by the same 2 bolts (the one also holding the trigger guard and the one on the metal tube beside it) ? or did you make changes there too ?
I have a CP1, which does not have a vent hole in the tube, so I was thinking of using it's tube entirely as plenum and then put a regulated cylinder in front of it.

[Racing]

Valve housing in itself is stock.
Fact is, the entire flow path is still stock. Havenīt change any dimensions what so ever.

The install of a PEEK poppet on a 2mm hardened steel rod, what you do apart from turning the actual poppet is install a "bearing insert" to the stock valve.
As others have taught me here on GTA a difference in performance is to be expected, which really holds true the higher the output of the piece is.
As iīve pulled this stunt a number of times by now this particular gun was interesting as itīs the ONLY mod per se done to the "flow path" in itself.
Of course the difference will just enhance the more power you ask from the unit.

But.
This isnīt about maximum power. By far.

The unit no doubt needs more air.
Yeah. I get it, the "original" design idea of it, all good. Pushing the envelope even in the slightest as far as this tho, different matter all together.

More air.
What i hadnīt done was "scavenge" the shop. Me iīd just been looking at the steel tubing at hand. Then it struck me.
Go big or go home.



As we all know Greta by now, repurposing stuff is the wave of the future no doubt 
So that there is the stock bottle for a BSA R-10 and the point here is that itīs isnīt far off weight wise from using steel. Major difference being that the bottle is already there.
So.
A drop block to make the thing fit. A "load bearing" pieces of rings put to it... and done deal.
That would render 240ccīs total.

Yeah.

[louigi600]

Well my question was more focused on how you hold in place the valve assembly because one thing is that all you need to is pierce a CO2 cap and the relatively small area where pressure is exerted (cant not be physically bigger than 0.4 cm^2 but likely much smaller) on the seal and whole other story is the regulated pressure exerted on the entire face surface of the valve assembly (somewhere in the range of 2.8 cm^2).
Now being that the regulated pressure will be likely 2x higher than CO2 (if unregulated the pressure likely 3x) and the area 7 times bigger that's no less that 14 times the force.
Now on the CP2 there is only one permanent M4 bolt holding the valve assembly in place ... the second one is also holding the trigger assembly which finally also locks the mechanics on the stock.
Assuming a regulated pressure of 120bar:  that's 340 kg  (3338 N) all held in place by just one M4 bolt  sideways ... is there not a risk of the M4 bolt getting sheared ?
You are the engineer: how much force does it take to shear a standard steel M4 bolt ?
I searched that but only found the info for bigger bolts ... assuming the shear force capability is lineal with cross section area
M12 is capable sustaining a single shear force of about 32kN assuming the cross sectional area of M4 is about 1/16'th of that  that would mean 2kN which 1.3kN short of the pressure exerted on the valve assembly from 120bar. I would be scared to unscrew the trigger guard bolt while the thing is pressurized.
The trigger guard bolt is actually M5 so with that in place there is somewhat some margin as the 2 together can likely take a shear force > 4kN + whatever friction when they are tightened against the side of the tube

[Racing]

@ David.
No no no no...
This is a HPA gun from the onset. A pcp. Runs on 200 bar stock. However, seeing the to be repurposed BSA bottle iīm going to add a couple of allen screws to the valve body and run it on the BSA granted 232 bar instead. Only "weak" point of the system IMO, and common for all these Snowpeak offerings as i regard it.

Trigger assy on this one is a stand alone piece of kit. Like on the Stormrider/PR-900 is rides in a separate folded over piece of heavier gauge sheet metal thatīs welded to the tube.

Yes. On the pcp PP-800 thereīs still just A screw keeping the valve assy in place and TBH that feels kind of shady if ever. So the plan of mine is not only to add a couple but to make them 12:9 too. So cheap as far as insurance itīs downright folly not to, seeing how theyīre implemented.

From an engineering standpoint a screw in single shear is a mortal sin really. Youīre taught to NEVER do, but if needed.. go ape on safety factor. Thus if you HAVE to do so always count in for safety factor galore.
However.
For the PP-800 parts of the tube keep indentations to keep the valve body from going out "the wrong end", which of course helps a ton - but to be honest is just a cheap manner in which to make do to save on manufacturing costs. A band aid setup if you wish. Those indentations are by far anything sure fire, h*ll no even.
In short, cutting those to keep the valve body secure is just a cheap fire way of making do at an utmost budget.
For an engineer though itīs a p*ss poor "solution" to anything really.
No wonder however seeing the price point on these units.

That said youīre a tad off on your calculation basis.
Check google.
For starters when into mechanix you get area by ; diameter square times Pi divided by 4. All to aware of radii square yadda yadda.. When into the mechanical side of things tho..
For various reasons (as you dig deeper youīll soon enough get the grasp) go with; diameter square times Pi divided by 4. For volume just add distance as in times distance, but make sure you do so according to same entity.
Ie; cm for cm and so on.

In turn thereīs no such thing as "an M12 will take force X". It depends on a number of variables and is not a matter of diameter or type of load only. Far from it.
If you want to learn the basics google Sigma 0,2/steel. Thatīll get you started at least.
Steel, in any app really, is a WAY to common nomer to tell anything. For the sake of argument in turn, remember what i wrote above about single shear, is that a regular M6 8,8 will take a load of a ton and live to tell about it if just applied correctly (pull). As an example most aeroplanes have their wings set with all in all 4 pcs of screws. No. Not a misprint.
The thing about threaded fastneners is that they were never intended to be loaded in single shear but to pull various construction elements together.
Thatīs what theyīre REALLY for.
Then. A screw carries threads. A bolt, at least to us over here in Europe, is a rivet with a hex head. That we use the nomer "bolt" careless is a different matter.

My "speciality" at the time was whatīs these days partly known as FEM. To me at the time, numerical analysis. Ie; we all know that if we load something hard enough itīll break.
Alright.
What if we impose a slighter load, just at a frequency back n forth... how long will said element survive before being exhausted to the point itīll break.?What if the load varies over time? Or goes back n forth? How long before it starts to "decompose"? Showing fatigue, stress cracks.. how long before itīs unit loading capacity starts to be compromised?
We often design for this. Take a 747 Jumbo for instance, itīs designed to have its wings "flap" around along the lines of approx 12 meters under load.

[louigi600]

@Racig
Well I made the mistake of assuming that M4 is 1/4 the diameter of M12 ... but it's not it's roughly 1/3 so the shear force for M4 would be roughly 1/9'th of that of a M12.
But sill I think the 32kN one must have been a fairly good one. I later found some M5 rated for 2.7kN shear force. M4 will likely have 64% of that shear force (1.73 kN).
OK a lot depends on the material and the manufacturing process ... I would still like to play safe on the lower end.

As for he PP800: no the tube is notched to take some of the force off the single bolt on the valve assembly... the valve assembly cal only be extracted forward. Ok it's a cheap solution to fix the issue they notiuced that the bolt was over stressed and could untimately fail. They did not want to invest on a redesign so the notched the tube.
Well I have not taken it apart to confirm what the outside appearance is but you can see the notches on the outside of the tube. First time I take it apart, if the force is not also spread on the notches, I will also likely put  a couple of extra flush allen screws to share the force.

Is i possible to cut functional o-ring groves without a lathe ?

[Racing]

Cutting grooves could in practice be done with a hacksaw blade and a power drill for instance but...
The issue is twofold.
Lack of surface finish and in practice control of dimensions.

So iīd say no.

Cutting o-ring grooves in turn, for some reason those not in the loop are often of the idea that the fit should be tight. Thatīs one surefire way of making sure the o-ring wonīt work as intended. Direction of the pressure the o-ring needs a tad of "end shake" or it wonīt be capable of performing its task.
This to an extent holds true for how it meets a bore up as well, the basic idea being that what makes the o-ring seal is the pressure. Many seem to have lost track of that.

Often times, as o-rings can be of real "weird" dimensions i tend to shape a piece of HSS steel to fit to turn the groove on a lathe. This way the dimensions on the o-ring/s can be like whatever as you can tailor the groove as you see fit.

Of course thereīs also applications where itīs not as anal as far as that. For instance to seal a shroud tube up and the likes. None the less, correct is correct and thereīs no two ways about that.

In turn. Again.
Loads, from a practical POW, canīt really be applied per your reasoning. School book examples tells very little. For a "free examination" setup download a decent CAD program. End of that thereīs usually some sort of FEM analysis software that can be put to good use.

[Racing]

Btw.
As far as having the valve assy stay put.
Of course thereīs a gazillion ways of implementing that but if we stick to the typical Artemis setup (as well as Chief and what not) thereīs mans that perform this a little different.
They use cap screws and set the diameter on the tube to capscrew head diameter. Thus "floating" the install on whatīs a larger dia screw head vs the thread. Not an all dumb move IMO as weīre indeed talking single shear here.

[Racing]

Plz take to heart itīs very much still a work in progress. Might seem excessive, and it is from a looks point of view i guess, but the reason i made that aluminium bracket for starters was to get an idea of total weight and in turn balance. Ie; able to hold the thing up with the pts installed.
As it turns out, not all bad. Really.

Yet one aspect here is that whatīs being done is 100% reversible. Ie; iīll most likely make the smaller all steel setup too, and then let practice decide what stays.
What IS for sure though is that the pew needs more tank capacity, that much is beyond debate to me.

[Back_Roads]

 It worked for my Jet1 with cf bottle, but I switched to AL after as I wanted the bottle on my Notos, now both strictly carbines. LOL.

[Racing]

Looks kind of neat, have to say.
How do you find the unit to use?

Me iīve been pushing... time being the major constraint really, but itīs sunday after all.. and it is what it is.



I wanted the actual drop block to be out of steel, for obvious reasons i hope. So first up turned the thing to reasonable dia on the lathe, drilled the ports out, threaded the end to take the pressure gauge and what not...



As you can see not all that much to hold onto the drop block. Going to thread that there M10*1 (as many pressure gauges these days) and set it by brazing all said. This will provide for a secure hold that in turn is dead on free from any leaks.

The bung going into the stock end cap for the tube though, where the pressure gauge resides stock.. now itīs starting to become a tad to small to my liking. But again... it is what it is.
Thread is M8*1.

Hence that bracket i fabbed IS no doubt needed. Will hand it a few grub screws to secure it both to the bottle and the tube.
That done, 240ccīs here i come! 

Point being, that BSA bottle really IS small. Dia on a mere 50mills..


That said the stock end cap keeps a hole for the pressure to reach the gauge right. That hole is rather small why iīll enlarge it - within reason.
Point being that the stock 40ccīs will no doubt suffice to feed the actual valve all it wants, why a smaller dimension "fill port" between the bottle and the tube will be of less consequence i believe.
The valve assy for filling the unit up is thus skewed off center a bit already as they come. In other words, all needed is to take a slightly larger drill bit to that hole and done deal.

[Back_Roads]

 Here is a demo