Uncle Hoot, thank you for enlightening us all and lightening the mood in these dark times — corona pandemia upon us
— and carefully listening anti-gun neighbors upon us....
I had a problem with the virtual mouse in the video, though. I was just getting ready to test my PP700 at 13.7FPE against the mouse fart... — when my virtual cat came and ate the mouse!
Pizzaman, I'm just now eating what one of your colleagues has brought to my house, yummi!
I'm with you in your quest of quieting your pistols, as they are ideal urban pesting tools.
I have tried many different tunes with my .22cal PP700S-A, and I'm still learning about how to play the PCP game.... Here are my observations (interpreted through what I read on the forums [thank you, rsterne [Bob Sterne] at GTA!]).
Please, correct me if I got this wrong!
(1) The biggest challenge to quiet a pistol is that we want to
keep it short, small, and light (
the opposite of big silencers) — otherwise, why not just use a rifle?!
But you are already fine with using a big silencer, so far so good.
(2) Of course: Generally,
less muzzle energy, and a
smaller caliber reduce loudness, and
silencers that are the same caliber as the barrel rather than larger.
However, DonnyFl recommended in a personal email the .25cal Sumo for the .22cal PP700 — as that was his choice for his personal gun. The added loudness is supposedly not very much more (it's just one caliber larger) — and an oversize reduces the danger of pellet clipping greatly, especially with shrouded guns.
(3) I have a
Silencer Specs List with 50 models to drool over (attached below). However, mrbulk's testing (over at GTA) seems to point to the following conclusions:
For
midpowered and
shrouded PCP's most silencers will do a pretty good job, with only small differences between them!
But if the gun is high powered, or not shrouded, the silencer has to do a lot more work, and that is when
more volume of the can will make a big difference.
Our PP700 (either W or S-A model) does not have much of a shroud, but it's at least low powered....
(4) And now to an important factor that is easily overlooked:
the kind of tune you are using. I could get the same power (12FPE) using a high regulator setpoint (REG 100) with a low hammer tenstion spring setting (HST 1.4) — or a low REG (85) with a high HST (1.625). The first tune will be quieter than the second tune.
Here are some real life numbers for the following gun/pellet:
▪Gun: Artemis PP700S-A .22cal w/ Huma and w/ DonnyFl Sumo .25cal
▪Pellet: H&N Sniper Light 14gr
Tune #1 (cf. the first HST string chart attached below):
5% MV below the "knee" [the max. velocity at this REG/HST setting] = 627fps (12.2FPE)
REG
85bar | HST
1.625 turns out
Loudeness: Rather LOUD! I had to stop sniping.
Discussion:
5% MV below the knee are are middle ground to get the most power with the most shots (efficiency) (Bob Sterne).
Tune #2 (second HST string chart)
10% MV below the knee = 665fps (13.7FPE)
REG
130bar | HST
0.25 turns out
Loudeness: Rather quiet — though not mousefart.... This is my current tune.
Discussion:
10% below the knee are more efficient than 5% (more shots), but produce less power.
10% make the velocity slightly creep up throughout the regulated shot string.
10% are better than 5% for quieting the gun: 10% make the hammer slap the valve open for a shorter time than 5% because the pressure (REG setting) is so high that no more is needed. This results in shorter but more powerful sips of air when compared to a 5% setting producing the same amount of power, where the valve stays open for longer and the necessary air takes more time to send the pellet on its way.
Tune #3 (second chart)
Incidentially, I get more power with the Tune #2 than with Tune #1, with less loudness.
Now, I could increase the HST further to get the MV to
16% below the knee (HST 0.5625), which would give me
621fps (12FPE), the same as in Tune #1.
However, I fear that at 16% the velocity variations between shots will be much larger, and the velocity creep-up as well.
Loudness: Probably quieter than Tune #2 (and #1, of course).
Tune #4 (third chart)
So, to further reduce loudness, I could get the gun from 14FPE down to say 12FPE.
For that I'd find a regulator setting, where the knee is 10% above my desired velocity (in this case, for 12FPE that'd be 620fps).
The third HST string chart has the reg at 100bar. The knee is at 685fps. 10% below that is 616fps. And this is 12FPE (11.8). So:
10% MV below the knee = 616fps (11.8FPE)
REG
100bar | HST
1.4 turns out
Loudness: Probably quieter than Tune #3 and #2 (and #1, of course). 
➔ I'd like to try this tune — next time the o-ring in the entrance valve goes out yet again....
What are your perspectives on this? Do I understand this correctly?
What do you suggest?
Matthias
Attachment Silencer Specs Table:
View attachment SILENCER Specs Table. 20. 2020-10. TABLE.1606954154.pdf FIRST HST String Chart: SECOND HST String Chart: THIRD HST String Chart: 
gun.
