How many shots to break in a (regulated) PCP?

[nervoustrigger]

If the velocity keeps increasing all the way to end stop on the adjustment screw, how does one know if it’s a matter of needing a stiffer spring, or the regulator being set too high?

Well, it's not one or the other.  It's both simultaneously...just have to choose which way you want to go to deal with it.  If you want to tune to a higher velocity and are willing to accept the lower shot count, increase hammer strike.  If you want to tune to a lower velocity and increase shot count, reduce the regulator's setpoint. 

You can indeed shim the hammer spring...up to the point it reaches coil bind and will no longer permit cocking.

[Wayne52]

Jason with all your tuning experience I'm thinking that 140bar on the reg will probably give me about 60fpe.  Kevin I ended up robbing the scope rings from my SPA Varmint because there wasn't a scope on it.  I could have made the Picatiny rings work with the adapters however I'd rather have good medium scope rings on it that aren't a mixture.  The 11mm rings worked but only with the single shot tray.  I'll be sending that stuff back soon.  I think that the 4-16X scope will work out just fine though.  Eventually I want something on this gun with side focus though but this scope will work out fine for now, I just haven't gotten out to sight it in yet.  The scope that I had on it was basically the same scope except it was 12X and belongs on my DAR22.  The Varmint I haven't even shot in a couple years and the pressure in it is right about where I left it the last time that I shot it.  If it is a good scope I'm thinking I'll be able to easily do hole in hole shots with it at about 50 yards but eventually I'll be shooting slugs from it for ultimate long distance shooting.  This gun I plan on shooting in the spring in a blind for coyotes and also during the warm weather crow season.  My SPAM16 has all the other bases covered big time.  I watched 3 guys a couple years back calling in crows and they were nailing them left and right.  You really need to have como on for hunting both crows and coyote here and they're about the only thing you can wear camo with when hunting except for a bow.

[DrGunner]

If the velocity keeps increasing all the way to end stop on the adjustment screw, how does one know if it’s a matter of needing a stiffer spring, or the regulator being set too high?

Well, it's not one or the other.  It's both simultaneously...just have to choose which way you want to go to deal with it.  If you want to tune to a higher velocity and are willing to accept the lower shot count, increase hammer strike.  If you want to tune to a lower velocity and increase shot count, reduce the regulator's setpoint. 

You can indeed shim the hammer spring...up to the point it reaches coil bind and will no longer permit cocking.

I am learning! I’ll test & see where my velocity is & if it stops rising. I plan to lap the bore a bit to speed up break in, it looks like it could use a polishing. Off on vacation for now!

Thanks for your help-

DrGunner

[DrGunner]

Jason with all your tuning experience I'm thinking that 140bar on the reg will probably give me about 60fpe.  Kevin I ended up robbing the scope rings from my SPA Varmint because there wasn't a scope on it.  I could have made the Picatiny rings work with the adapters however I'd rather have good medium scope rings on it that aren't a mixture.  The 11mm rings worked but only with the single shot tray.  I'll be sending that stuff back soon.  I think that the 4-16X scope will work out just fine though.  Eventually I want something on this gun with side focus though but this scope will work out fine for now, I just haven't gotten out to sight it in yet.  The scope that I had on it was basically the same scope except it was 12X and belongs on my DAR22.  The Varmint I haven't even shot in a couple years and the pressure in it is right about where I left it the last time that I shot it.  If it is a good scope I'm thinking I'll be able to easily do hole in hole shots with it at about 50 yards but eventually I'll be shooting slugs from it for ultimate long distance shooting.  This gun I plan on shooting in the spring in a blind for coyotes and also during the warm weather crow season.  My SPAM16 has all the other bases covered big time.  I watched 3 guys a couple years back calling in crows and they were nailing them left and right.  You really need to have como on for hunting both crows and coyote here and they're about the only thing you can wear camo with when hunting except for a bow.

Wayne- that scope is barely used. I bought 2 of the same, mounted them both, and found that I always reached for the RWS 36 when I wanted a scoped springer. I ended up mounting a red dot on the RWS 45, so that 4-16 went on the shelf after dial in. I probably shot less than 50 pellets with that scope mounted on a rather tame springer.

Hope it works out well for you-

DrG

[Back_Roads]

 Like Jason implied, the hammer spring allows you to tune around the regulator set pressure, there is usually a sweet spot around each reg. set  pressure. Going to a higher set pressure may require a stiffer hammer spring, but one can determine how much stiffer by adding different size shims, though you may be hampered by coil bind, that is where a stiffer and possible slightly shorter spring may be the best final solution to higher power., Limited by reaching the point where you are pushing way too much air out after the projectile has left the barrel.
 So far I am satisfied with mine shooting at 50 FPE with 37.6 gr. bullets and 25.4 gr Air Arms dome. Later today weather permitting I will do some more shooting I may attach my clamp on crono to get instant feedback  on some fun plinking. 

[DrGunner]

Finally got some real testing done.
I’m getting excellent accuracy out of JSB 25.39gr at 940-950 FPS, and 33.98gr at 845-855fps. I adjusted my hammer spring @ 1/4 turn increments and it stopped gaining speed 1.5 turns from fully seated. I backed it out in 1/8 turn increments and found the velocity did not drop until between 1-3/4 & 1-7/8 turns out from seated. I left it at 1-3/4 turns out.
At that setting, I’m getting 20 good shots per fill before it falls off the reg. My regulator gauge sits a tad below 150bar, I’m thinking it’s set around 145. I don’t think I’m going to bother adjusting the regulator... Right now it’s shooting well with decent efficiency.

 “Good’s Worst Enemy is Better”

I must post a shout out to Wes @ AirgunArcheryFun. My rifle developed a slow leak from the intake valve from the start, which was minimal at first but worsened with use.
Following Wes’ excellent instructions, I replaced the intake O-ring... 3 times. It never did hold air. It turned out that whoever installed the funnel screw that holds the intake O-ring overtightened it, and galled the aluminum and chipped the anodizing where the intake O-ring seats. Wes sent me a replacement intake assembly that he confirmed to hold air @ 250bar before sending it.
I got it last week, shot the M11 a bunch Saturday & Sunday, and verified it’s holding air this morning.
Wes is good people, excellent customer service and very helpful instructing NOOB customers like me. Hes gone above & beyond what he needed to, always answering my emails quickly and patiently- even on weekends & evenings.
I’d recommend his shop hands down and would not hesitate to buy from him again.

Regards, 


DrGunner