Regulated .22 B50 results

[MartyB]

Finally got a full string on my regulated .22 B50.
Here's the build is it stands.  Milo74 regulator set at 1600 psi, Hillman #152 hammer spring, Hillman #83 valve spring, delrin transfer port .116", valve opened up for better flow and the striker adjusted about 1/8" out from the nose of the standard heavy hammer.

JSB Exact Heavy 15.98gr from 3000 psi fill, I stopped at 63 shots.
Guessing it dropped off the regulator at about shot 54.  Doing the math on that I get.

853.523913   Average
4.706174893   Stdev
21.1   Range
2.45   ES %

Not super, but pretty good for the amateur like me.   The regulator has around 200 shots through it.  Going to give it some more time and see if those low 840s even out with the rest.  If those were smoothed out to 850 fps, the rifle would be at 1.69% ES.

Sorry about the formatting.   Strings are formatted vertically

String    1   2   3   4   5   6   7
   850.4   859.9   850.4   855.5   854.4   850.5   828.5
   845.9   841   858.5   852.1   848.4   856.5   err
   861.9   857.8   851.3   855.3   848.5   852.8   820.3
   847.5   850.3   859.3   855.8   853.2   849.4   
   err   854.5   err   err   err   err   
   853.2   848.4   862.1   854.5   843.9   834.3   
   err   852.5   858.5   855.7   855.8   840.9   
   err   857.1   858.5   856.6   850.9   832.4   
   860.5   857.2   err   850.1   849.2   833.2   
   err   854   849.1   858.3   854.9   833.1   
            

[Motorhead]

Not to shabby for a .22 cal and also using that MASSIVE factory hammer.
There's more there 

[MartyB]

Not to shabby for a .22 cal and also using that MASSIVE factory hammer.
There's more there 

Thanks.  I know there is more to be had, but need to gauge my own appetite for trying to squeeze out a few more shots.

[rsterne]

About 55 shots before it went off-reg?....

Bob

[MartyB]

About 55 shots before it went off-reg?....

Bob

Your guess is..... a lot better than mine!
My original goal goal was 29 fpe, so the plenum is just over 29cc.
I switched from the 18.1 to 15.9gr JSBs which adjusted the goal to 26 fpe to put those into the mid/upper 800s fps.
Hit that goal and it's fairly efficient going by ear.  With the clague ldc, the pellet hitting the trap is far and away the loudest part of the operation.
I've got limited tooling available, home wood shop setup for cabinet and case work.  But if you've got a simple suggestion to try I'd be open to it.  Otherwise I may call this one good and move on to the new .177 B50.    

[rsterne]

So you're at 55 good shots at 26 FPE?.... That's a total of 1430 FPE from 3000 psi down to 1600, and you probably have a reservoir of about (196-29-18?) = 150 cc.... That's 97 bar x 9.1 CI = 883 CI.... which is 1.62 FPE/CI.... If that is accurate, that is STELLAR efficiency, I wouldn't change a thing....

Bob

[MartyB]

Thanks Bob.  Don't know the final pressure for sure, so likely a lower efficiency.
But I'm happy with the 55 good shots.
I'll finish re-zeroing the scope (lots of tearing this down and reassembly) and wait for warmer weather to get to the range.
Now on to the .177!

[SpiralGroove]

Hey Marty,  Nice Job!!
Didn't you go with a Delrin hammer/spring guide?  I can't remember .

My goal, (when I get around to doing it) was going to be 50 shots at 825/850 fps with 15.99 JSB's.
Kirk

[MartyB]

Hey Marty,  Nice Job!!
Didn't you go with a Delrin hammer/spring guide?  I can't remember .

My goal, (when I get around to doing it) was going to be 50 shots at 825/850 fps with 15.99 JSB's.
Kirk

Nope.  Stock hammer and spring guide.  So that hillman 152 spring has a lot of mass to move.

[rsterne]

The final pressure doesn't matter, I only counted the shots to 1600 psi, which you said was the setpoint.... If that is not the case, then the math will also be in error....

Bob

[MartyB]

That is the set point.  But I think we both question if 54-55 shots is really when it drops off the regulator.
Will have to get another string with the pump connected to monitor reservoir pressure.

[Pellgunfun]

I may end up going with the OEM Hammer and spring guide as well.  At the top end (2900 psi) the Delrin Hammer and spring guide is just not strong enough.  I haven't tried the Delrin Hammer and spring quide with the OEM spring.  That will be next on the list.  It's so cold hear I'm not about to spend and hour or more in my garage.  My little heater just won't keep up:)

[Motorhead]

Just some FYI on working with Light hammers on the regulated BAM's ....
You CAN take nearly all the nose off the hammer increasing stroke that amount.
May need to add spring preload as you do, but so long as no coil bind at full cock your good to go 

Trial & error the only way to fine tune the balance however