Tuning Artemis PP750 - time to start modding

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Most excellent work!

Looking forward to lower assembly...
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I like to combine multiple functions into a single part and the geometry becomes complex for conventional cnc machining, I may outsource for laser sintering.

Lets have a look the rev.6 prototype parts above, in a single part:

- minimize the overall outer dimensions but having a larger internal plenum volume + an external reg gauge + two picatinny accessory rails pockets made this part a 6 side setup on the cnc.
 
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I see many waiting for some numbers, so here they are for .22 Canadian version (sub 500 fps=152.4 mps or sub 5.7 joules=4.2 fpe)

20201209_205309.1607571067.jpg


First about question how long is the air tank with the new Plenum?

- I offset the plenum 10mm hole and the airtube now have a 2.5 mm clearance to the shroud and sticking out at front for 4mm. I am planning for a longer barrel anyways so this is not a concern to me.

I have drifted away from out of box conditions, my changes are below:
- polished all moving parts (cocking mechanism, sear and trigger, air vented the hammer), also the Reg bevel washers;
- replaced the original HS for reason I believe it was just way to harsh on cocking lever. Old spring 6.6x1.1x65 to a new SS spring (McMaster) 5.9x0.78x50. Now the cocking is almost butter smooth, but...
- because of a shorter spring I added a brass hammer weight 5.1 gram

I had this PP750 for couple weeks, but did the cleanup and modifications first also waited long for the new Plenum, and only Today was a very first time to air it up.

- Fillup to 250 bars
- Reg setting is factory, I mark it before taking it apart.
- Reg pressure fluctuates between 94 to 97 bar, I believe this is normal until the Reg settles.
- Crappy Crossman 14 gr domed pellets;
- factory 8" barrel, so far I didn't bother cleaning it yet;
- FX radar chrony;
- Edgun digital Reg gauge;
- shot string 15 with average speed 494 fps;
I stopped counting the shots somewhere after 30 ish +, because maxed out the hammer spring. This spring is either too soft (CS 0.78 vs 1.1) or just way to short for 15mm (50 vs 65);
I will re-do the shot counts next time I have a better spring, but anyway, a dwell time on a Reg or a HS-HW combination shall be very close.

- And...the air dropped from 250 bar to somewhere about 180 bars.

I don't have numbers for out of box condition Canadian PP750, but you may have something to compare this Plenum.

More to follow when I secure couple new cans of 22's
 
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Will he ship to UK
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The problem is not with shipping but with administering emails/orders/quantities/packaging/shipping....

Couple years ago I have co-owned a kickstarter crowdfunding project, it was a nightmare and I promised myself I will never work with individual emails again.

I have proposed in a conversation with Wes from airgunarcheryfun if he would take it.
 
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Canadian 1.8mm port vs. 3.5mm port. Factory plenum, no additional modifications or polishing, with the 3.5mm port and reg at 1700 psi (117 bar) could push 18.13 gr at 580 fps for 50 shots.

A larger free flowing plenum with 3.5mm porting would be impressive



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Tested ... and this plenum can beet the shot count numbers with a Reg 97-94, I stopped counting after 2x30 ish and some plus

Next hint, I just did it :)

First why I did it, then comes to how I did it.

I noticed that if I single load the pellets (.22 here) the Edgun Reg gauge stays in a 99-97 bar ballpark.

If I shot a string of 7 from a mag, the Reg drops down to 94 bars.

The plenum is running hungry. Need to mod the Reg to work faster (and not harder).

Before next topup I tok the Reg apart.

The small little hole in a Reg threaded puppet have a hole of 0.52 mm I enlarge it to 0.72 mm. H da H I could measure and doit? ;)

{Next time you visit your dentist, ask the "Mr/Mss" for used disposed drills...you know those that hurts ... they are using those micro sizes all the way up to 1.2 mm...scary}

Feed the Reg to be able to do the work?

Top it up, the Reg is on 160...Testing tomorrow, now is a quiet time in the house.
 
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Canadian 1.8mm port vs. 3.5mm port. Factory plenum, no additional modifications or polishing, with the 3.5mm port and reg at 1700 psi (117 bar) could push 18.13 gr at 580 fps for 50 shots.

A larger free flowing plenum with 3.5mm porting would be impressive



PP750 ports.1607631535.JPG
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Thane, any ideas why my .22 only gets 20 shots at around 580? I shoot from 250 bar to 90 bar. Mine was tuned by Veradium Air. This week I added the Huma reg but not much changed. Thanks!! Bryan
 
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Bryan,

Thats a low count and low velocity. May have a leaking oring at barrel thimble, sticky poppet, blockage, air cushion in front of hammer... too many things to guess. Needs to be opened up and checked.

For comparison with 4mm plenum port and valve port, reg set at 140 bar (similar to Veradium modifications) PP750 .22 with 18.13 gr was doing 35 shots at 660FPS for 17FPE.
 
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Bryan,

Thats a low count and low velocity. May have a leaking oring at barrel thimble, sticky poppet, blockage, air cushion in front of hammer... too many things to guess. Needs to be opened up and checked.

For comparison with 4mm plenum port and valve port, reg set at 140 bar (similar to Veradium modifications) PP750 .22 with 18.13 gr was doing 35 shots at 660FPS for 17FPE.
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Thanks Thane. I can set my 750 to shoot into the 700s and I still only get 20 shots but fewer on reg. I set the reg to 90-95 bar thinking if I bring down the power I'd get more shots but it's still only 20 but 18 are on reg with a 7 spread. I was thinking maybe my HS was too heavy.
 
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LDC and over 500fps in a pistol both illegal in Canada. 🙄

Use your brain and stop posting about this Attila. This will bring negative attention for all of us.
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I understand and I don't use it myself. Thanks

The intention is/was only for testing the new plenum which is meant for trades outside of Canada. Without a plenum I don't know a way to boost up the power ...

 
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