Artemis PP800 .22 - Tuning

[skiron]

Hi guys,

Recently added an Artemis PP800 .22 cal pistol in my arsenal and need some advise to tune it...(I have already tuned a 38 fpe 24 shots 4% ES bottled prod and was pretty easy so I have some experience, but with the PP800 it seems that I can't move on with this awfull bell curve, low power and extreme ES :/ )

I'm posting a shot string with current settings to have a first look:

- Stock pistol's barrel
- No porting yet (fyi factory transfer port is 3,5mm ID)
- I initially cutted 3 coils from the stock hammer spring since my first test string with factory settings was falling like a rock from shot #1 (indicating to much hammer force), but the energy droped a lot for my desire with the shorter spring mod, so I added a total of 3mm preload with washers inside the hammer
- Pellet I used for the string below was Predator polymag short .22 cal 15.89 grains
*some xtra data fyi: gun is obviously unregulated, it has a 50cc air cylinder capacity, and the valve stem protrudes just a tiny 1mm (or even less..haven't messure it) from the valve face (first time seeing this in a valve..!)

So...here is my current string: Starting pressure is 220 bar (3.191 psi)...for ending pressures see below

Shot  FPS           FPE          END BAR
1   507,9   9,10   
2   509,4   9,16   
3   512,4   9,27   
4   530,2   9,92   
5   540,8   10,32   
6   551,7   10,74   
7   552,0   10,75   200 bar
8   556,0   10,91   
9   564,1   11,23   
10   578,1   11,79   
11   595,4   12,51   
12   587,1   12,16   
13   589,4   12,26   
14   570,7   11,49   170 bar
15   558,1   10,99   
16   577,8   11,78   
17   560,4   11,08   
18   531,8   9,98   
19   520,0   9,54   
20   510,9   9,21   
21   514,0   9,32           150 bar

Average FPE   10,65   
Average FPS   548,5   
ES fps      87,5   
ES %      14,70% (not accepted!!!)   
Efficiency      1,04   (not good..)

First of all, as you can see extreme spread is way toooo much...need to make it flatten somehow.....I can't use Bstalley mode since the valve stem protrudes really minimum from the valve face nor to use a regulator since I'm after maximum power for 14 shots...
Secondly, it seems to me that I'm wasting air but I have no signs of hammer bounce... all reviews and posted shot strings I have read for this gun, present that I should have many more shots in this low power +/- 11 fpe level from the 50cc cylinder. Some reviews for diana bandit (which I think is the same gun, right?) also show way more energy (eg at least 30 shots from low 10 fpe to high 17 fpe with factory settings as shown in this thread: https://www.gatewaytoairguns.org/GTA/index.php?topic=156037.0 ) so I assume that something isn't right here with my gun efficiency/power...)

Anyway...my goal is to have 2 magazines (14 shots) in the highest possible power (ideally not droping lower than 12 fpe with appropriate pellet), and with the best possible extreme spread.

What would you advice me to do with this little lego gun??? Is it doable to have 14 shots >12 fpe from this 50cc cylinder?

[skiron]

ps. I know that diana bandit has a 50cc cylinder....so pp800's cylinder capacity suppose to be the same 50cc but I need confirmation on this...

[Piranhaboy]

I have a Pp800 and a bandit, both have the same cylinder, parts swap between both.

[Piranhaboy]

How does the breech O ring that seals on to the bolt look?

[Piranhaboy]

Where did you purchase the gun through? My bandit I purchased through PA came with a spring that gave a declining shot string from a full 200 bar fill. The pp800 I bought from Wes in Canada came with a much weaker spring to keep it under 500fps and it shot best at 130 bar till I replaced the spring and retuned it to shoot from a full fill. I Ended up just making mine into carbines with stormrider barrels. The small reservoir with the short valve stem seem to really do well with the longer barrel and high pressure.

[skiron]

Piranhaboy thanks for the cylinder's capacity confirmation.

ps. Haven't checked the breech o-ring (the gun is brand new so I suppose the o-ring is ok) but I will double check it after your comment.....(when I disassembled the barrel I didn't notice any obvious wear in the o-ring but I will pay closer attention to it to see if I have any loss of air (so less power) from there...but I doubt)

The gun was bought from Greece, so I guess is the standart version since we don't have power restrictions in Greece. However, the spring doesn't seem to be an issue since I can really increase power more than the maximum of 12.5 fpe pick that I have right now with extra hammer spring preload.....the problem seems to be the shot count/efficiency of the gun (and ofcourse the extreme (!!!) spread)... I already tryed with more preload to always stay over 12 fpe, but could only make max 7 shots at 12 to 14 fpe range

do you have any shot string (with the short pistol barrel) to post to know what could be accomplished power & shot count wise?

[skiron]

Theoritically speaking...is there a "calculator" that could tell me what's the maximum power I can achieve from a 50cc cylinder with 9.25'' barrel for 14 shots?

[Warburrito]

Long_Gun_Dallas may be able to assist with this.  He has extensive knowledge of the pp800 and has achieved some amazing results on that platform.

[skiron]

Thanks a million David,

I just did a search and already reading this: https://www.gatewaytoairguns.org/GTA/index.php?topic=164510.0 and this: https://www.gatewaytoairguns.org/GTA/index.php?topic=167640.0
Should get me started and give me a complete picture if my 12fpe 14 shots target is achievable:)

[Pelletjunkie]

Just put an Altaros reg in it, open your ports to 4 or 4.5mm and live happily ever after. I purchased my PP800 with the reg option. That little tiny air tube doesn’t have a bell curve, it has a rainbow. The only chance of some kind of sweet spot would be if you slow it way down. But that’s no fun.

[triggerfest]

https://www.huma-air.com/Artemis-PP800-Tuning-Pressure-Regulator
And you are done...

During the ordering process you can even mention your preferred power setting...

[skiron]

Thanks guys....so I guess that a regulator is the only way to go (at least for an acceptable es)

...I just wanted to know if the shot string I posted sounds normal for this gun regarding power and shots number, or if I was missing something and my gun was underperforming vs what's expected with factory settings.

Anyway....with such an already small air capacity of 50cc, do you believe that putting a regulator (with a 10cc plenum) will be able to reach 12fpe for 14 shots with porting and high pressure setting or I'm asking too much?
I already have a huma that never used in my prod....i'm crossing my fingers that will fit the pp800 also to give it a try

[Pelletjunkie]

I don’t feel like doing backwards math to figure out fpe but there is only one way to find out what your gun can do. No matter how fast it winds up being, at least it will be consistent. You won’t have to put a Mil-Dot scope on it so you can hit stuff. I think getting it in the 600fps range shouldn’t be too much trouble. Open up the valve port, transfer port and barrel port to 4.5mm while waiting for a reg. I think the Altaros reg is cheaper than the Huma. Mine works good. But I shoot .177.

[triggerfest]

If you set the huma reg to a certain power setting, huma should be able to answer how many shots you can do with I guess... Honestly, 14 shots in 12fpe does not sound unreasonable to me ?

[skiron]

Hope that 14 shots @12 fpe range it's indeed not unreasonable with reg set high....but with such a tiny cylinder you never know...:/
Anyway, I have a last thing to try before adding a reg....'cause this really short valve stem got me into thinking...I will update with my results in case anyone's interested.

Thanks guys

[Long_Gun_Dallas]

Just put an Altaros reg in it, open your ports to 4 or 4.5mm and live happily ever after. I purchased my PP800 with the reg option. That little tiny air tube doesn’t have a bell curve, it has a rainbow. The only chance of some kind of sweet spot would be if you slow it way down. But that’s no fun.

I'd like to see how large the altaros is and how it sits in the gun.

But otherwise this is how it is.  You WILL have a large ES without a regulator.  My calculations actually show less than 50cc unmodified.  Maybe they are counting the valve body volume as well.

The saving grace is that the barrels are not choked.  And as such, even with a large ES your groups remain very tight regardless.

I did spin my valve stem and seat.  And used a file and some sandpaper to cut the valve back so the stem could protrude further from the back of the valve body.  On my pp800 (25 caliber)  I also cut the back of the valve body back a bit as well.  Without modifying the shoulder that rests on the tube notch.

I have 5.1mm ports.  (were 3.5mm as you said).  And behind the valve stem it is 5.7mm.  Using a pr700w hammer spring.  28fpe max currently.  8 shots from 705-625fps.  Very tight grouping with 25gr jsbs.  First shot is a bit high.  Next two settle down onto my POA.  Next 5 are on the dot.  If plinking I'll shoot 10 or 15 more shots using hold over.  It's extremely predictable.

My bandit has some work done.  But mostly a huma reg.  and lightened hammer/cut spring.  7fpe in .177  51 or 52 shots at 650fps

Your shot string is actually better than what I would expect for this gun.  But likely due to the valve stem not protruding much.

I'd recommend porting it a little.  And cutting your valve seat back a bit for more actuation.  See how it shoots on target.  And if you arent satisfied, get an altaros reg.

[Pelletjunkie]

Porting on an unregulated gun makes it worse. More powerful yes. That tight 3.5mm porting is keeping unregulated blasts of air under control. Gun would be tighter with even smaller porting but then they couldn’t market it with a velocity that gets guys excited.

[Long_Gun_Dallas]

Absolutely.  I'm installing a 2mm transfer port on my 1322 to get it down to 650fps hopefully.  (And flatter fps curve) Darn thing is shooting over 800 fps with a sub 8" barrel and 16gr pellets      That's with hammer strike de-tuned

[Pelletjunkie]

Couldn’t you just put a couple less pumps in the 1322?

[KnifeMaker]

My very similar PP700 is getting 14.53 fpe for apx. 25 shots. Nothing more done to it than a better spring, dialed back and shooting my own cast 29 gr slugs. I could push it much higher in fpe, but for what I do with it, I need all the shots I can get. I hunt Scorpions with it having a black light mounted on it and a green dot Reflex sight from ADE.
Last season, I ended up with over 1837 killed with it. But didn't' start using it until July for my Birthday.

Very accurate with the  34 gr NOE Cast pellet, but the slugs are even more accurate! I like the slugs as the blow the rocks the scorpions like hiding under. Looks like a Miniature Artillery Attack LOL  
(The rocks my shooting berm is made of is ancient Sea Rock which is mostly calcium. It virtually explodes when hit with enough fpe)