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Thread: El-cheapo Artemis PR-900 - the mule

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  1. #1
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    El-cheapo Artemis PR-900 - the mule

    At the shop of mine the most dangerous of times is the coffee breaks.
    That´s when all the moronic notions and ideas are shot across the room. So. We started talking right and as the gang has a past within pro motorsports amongst other trades, yeah well.. we love hotrods.

    Question came up, me being a part time gun smith, how far can you push the cheapest of PCP guns when it comes to performance? Ie; both power and accuracy.
    Later the same day i saw an ad for this...



    ..which was a used Artemis 22cal PR-900 of Series 1. In short an about as basic PCP rifle there is. Forked over 120€ for it, it lacking its magazine. Still though, that´s not exactly a lot of money for a PCP and the thing was in great order.
    Back at the shop i popped like 10 round off, enough. At a mere 10J.. enough already.



    Well known i´d say!



    We use our PCP´s for pest control. Namely rats, and doing so we need to keep it quiet. The PR 900 lacks provision for putting anything out front basically so i turned a press fit adapter in a hurry, one sporting the industry standard 1/2"UNF thread.

    While at it i have to say (and as we were to discover) that barrel wasn´t half bad as far as the rifling and choke goes, however.. the muzzle crown coupled with the chamber and in turn the forcing cone HAS to be one of the worst jobs i´ve ever seen. Cheap rifle in its own right but hello!

    So. While the barrel was on the lathe we did a "first pull" as far as those bits, and as it turns out.. well..



    Yep. We turn our own cans. Hadn´t gotten around to make one specifically for the PR at that rate so simply stole the one off a Hatsan BT-65. Works for now, what can i say?
    Indeed it does make wonders for the sound level. No argument there.



    These guns do NOT sport anything close to a "match trigger", then again.. not to be expected on a 120€ gun. Parts out of what we´ve come to call "chineseium". Point being that they´re out of steel alright, just hardened to a point where it becomes stupid brittle.
    How i know?
    Well. For some reason Artemis decided it was a good idea to put the only adjustment there is, for creep, on the trigger blade. I however beg to differ so i took the centermark for a drill right.. and the sear just snapped off.



    Yep. Now, lucky me as i not only own an AC/DC TIG welder but know how to use it as well so albeit the parts might be small the thing was back in one piece in no time and WITH an added M3 screw hole for a grub screw so creep could now be set at the sear instead - where it´s supposed to be.



    Ah. Within the tank resides the valve of course, but a "depinger" as well that doubles as a tap off for the pressure gauge that sits underneat the stock. Never having worked on Artemis guns before i took to altering what was there.

    I bet someone will come to explain to me why, but for some reason Artemis seems to be hellbent on putting the softer piece of the actual valve n seat on the poppet.
    This, as power goes up substantially, turns out to have drawbacks. I must have reworked that poppet like 10 times before i went "to hell with it, i´ll redo the entire thing".



    It about came to drive me up the proverbial wall, cause where we were at that in later guise press fit bearing bronze seat.. it would move no matter the amount of press fit and even hard core industrial epoxy.



    In action pictures rarely tell of the finished product. But here.. that adapter, and at that the now reworked muzzle crown.



    For the actual valve pin these guns rely on a mechanical fit to seal the pin off vs the housing. Well, enough of that already so an endmill later we had countersunk the housing to take a 3mm o-ring. As the pin is 2,90mm though i fabbed a "lid" with a small divot that runs up against the o-ring and compress it. Presto, snug fit AND a way tighter seal - for air heading for the pill to be shot downrange.



    At that point i had enough of the stock solution so i turned a poppet out of solid hardened steel. Then a 12mm endmill to the valve housing, boring it out, to which i installed a POM (tough plastic) seat with the downright MASSIVE press fit of 12,30mm. Ie; 3/10mm.. Even turned a tool to be able to install the thing on the hydraulic press.
    Done deal and presto.
    NOW we were getting somewhere!

    At this time i drilled all passages out to 5mm flat and then in turn the valve seat through hole to 6,5mm. Poppet outer dia was set to 7,5mm, so as you can gather.. not all that much width to seal the thing. But it does, with flying colors.
    Last edited by T 20; 19-01-2022 at 07:13 PM.

  2. #2
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    that is looking good

  3. #3
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    Excellent thread!
    Last edited by Neil.; 19-01-2022 at 07:46 PM.
    1st Battalion Humberside Cavalier Rescue Deserters on the cut

  4. #4
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    At this point i had grown REAL tired of that rather "plastic" feel of the stock so out the sander came. Lo n behold! Who knew? Underneath like a TON of grain filler and in turn whatever that top coat is resided a rather nice piece of lumber! Handed that some dye (dark oak and mahogony) that has since seen layer upon layer of linseed and turpentine.



    Yeah. The rifle was back together. This was just after christmas however and my scuba tanks were low, as in REAL low. Fact is out of THAT very reason i came to take a look at the calibrated gauge on the one scuba to compare it to what the one on the rifle registered and HELLO!!
    100 bar on the scuba the rifle told me 160!
    At that rate though, yes.. that´s a LabRadar next to the gun and that thing doesn´t know how to lie, we saw some REAL promising numbers seeing the very limited pressures at hand.



    So there i was. Happily firing away when the dreaded "Series 1 issue" struck. Yes indeed, bolt handle sheared right off. Turned a new one in a jiffy just to get back to shooting... nice to have a decent lathe at times.



    These early guns have a reputation of not having their tubes and barrels in para. Indeed, rather far cry from it actually why i simply opted to cut the absolute top off the barrel band with a Dremel tool, leaving me with two "forks", one on each side which still provided me with the possibilty to torq down on the thing.
    Upon checking though... nah. Not even close.





    We indeed make our own shrouds and moderators. Simple enough i guess, and the key element apart from baffles is actually regular Wettex rag! Anyway.
    That can for the rather hefty Hatsan BT-65 about DWARFED the little Artemis so a fresh one of more decen proportions was in order.
    A rather long one as i wanted to be able to play around with baffles as i saw fit. All innards out of plastics, hence can NOT be used on a firearm.



    Hotrod. Indeed. At a rather early stage i discovered that the aluminium the thing was built out of released a sort of *ping* when fired. Just so happend that close friend had tossed the exhaust wrap for his engine in the bin.. one thing led to another and we were certainly with a moderator where *ping* was no more.
    Looks of it being a tad unorthodox i guess, but whatever..



    Bolt handle. Uhu, yet another boring lathe picture.



    ..and this is where it went astray, to say the least. Read on..

  5. #5
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    These guns lack adjustment for the hammer spring. Redesigning that more in depth was more of a chore than just going the other route, trapping the spring and be able to set preload as well as hammer free flight.
    Cause seeing where we were to end up, for the better. No hammer "de bounce" to be had, and this so called SSG setup takes care of that too, at least to a reasonable degree.
    Now.
    The Artemis PR-900 is a cheap PCP and it has to show SOMEWHERE and i´m here to tell you that it´s much a matter of fit. That end plug for instance.. No. Just..no.
    Seeing the SSG setup needed a guide to run off that protrudes through said end plug i simply turned a new one out of 7075T651 Aluminium and done deal.
    While at it i reset how the plug was held in place too.



    To make that guide run as it should the stock needed a relief cut at the rear. No biggie..

    At that rate i set the SSG up for 3mm of free flight of the hammer, for starters.



    Quiet is good. We like quiet, so although the moderator being there i also decided to fabricate me a shroud setup. Yes. Again POM (plastic) with an o-ring groove to seal vs the shroud tube and what not..



    Up front in turn, and adapter for the adapter!



    ´n here we go.. Slim piece of thin wall steel tubing.



    Shroud is set up "floating". Ie; axial movement of shroud is approx 1mm. Up front a small aluminium disc with a "step" is used to keept the front o-ring in check. This makes for a very simple and easy manner in which to first up keep the entire setup floating and second be able to install the shroud parts from the "rear" (with the barrel off). Up front there´s all this hardware bolted down remember..

  6. #6
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    Alright. So by now we had the scuba tanks filled, the SSG and what not all in place, shroud there as well as moderator, porting done yadda yadda yadda.





    Fudder, at least for current, is one of the two. Both of them JSB´s and both of them 25,4 grains. Take your pic. Interestingly enough the difference on target is very very slim between the pellets and slugs.



    Jäääääz... please This is what the LabRadar told. In fact highest recording that session was 1024. That equates to approx 80 Joules. Out of the most el-cheapo PCP you can ever imagine, and we´re FAR from done!

    Power is nothing without control though right?



    Yeah well, recall i told that we handed the barrel a bit of TLC? This at a mere approx 20 meters but still. That there is on par with what my Impact hands me. This out of a 120€ gun that by now has set me back still beneath 200€ total.
    Yeah, cheers!



    After a LOT of swapping of scopes i came to settle on a rather cheap chinese Zeiss rip off. Like the way it works at dusk.. a lit one. Add a bit of red and.. rats away!

    Done though?
    No. Not even close. This is "the mule" remember? Seeing the level of performance this thing has turned out to be capable of next thing up is the application of a so called buddy bottle.
    To be quite candid not a decision that came easy as i truly LOVE how the stock turned out and the sleek lines of the rifle. But the truth of the matter is that at the power levels we´re at, and furthermore where we´re aiming, them pityful 100cc´s of air tank simply doesn´t suffice...

    So yes.
    To be continued.. ldgrin

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