By changing "barrel length" only --- can someone tell

[nervoustrigger]

If you have the 850psi Ninja regulator with a coil spring, it can't be shimmed much higher.  Roughly 1000psi is as high as they'll go before entering bypass mode based on my limited experience.  The spring will need to be replaced with a stack of Belleville washers.  The 0.032" thickness is what you'll need for a setpoint in the 1100 - 1400psi range.  A qty of 12 is enough.

http://www.zoro.com/i/G0908275/
https://www.mcmaster.com/#catalog/9713K66

Plus some 0.005" and 0.010" shims to fine tune the setpoint.  I've always managed to play musical chairs with shims taken from the stock regulator to get where I wanted to be, but here's a shim pack recommended by nvreloader
https://www.zoro.com/precision-brand-arbor-shim-assortment-25120/i/G2234635/#specifications

[ray1377]

I don't think you can shim the coil spring in the 850 psi regs. up to over 1000, if that far.... 1200 will be fine on the 1.8K burst disc, I have had one fail at 1500, and all but one blow at 1600, I use 1500 as my maximum.... maybe just been lucky....

Bob

Aww Mr. Bob
that last statement of mine was purely wishful thinking on my part.
I've read enough of your posts to know that I'll need to change out the spring for bellville washers stacked in the correct
order to attain the pressure I seek. 
And yes sir I'm also thinking that there are no "standard" order of stacking that brings the same pressure every time.
I'm sorta looking forward to doing this for myself after reading all the posts on others designs and modifications.
Thanks
Ray

[ray1377]

If you have the 850psi Ninja regulator with a coil spring, it can't be shimmed much higher.  Roughly 1000psi is as high as they'll go before entering bypass mode based on my limited experience.  The spring will need to be replaced with a stack of Belleville washers.  The 0.032" thickness is what you'll need for a setpoint in the 1100 - 1400psi range.  A qty of 12 is enough.

http://www.zoro.com/i/G0908275/
https://www.mcmaster.com/#catalog/9713K66

Plus some 0.005" and 0.010" shims to fine tune the setpoint.  I've always managed to play musical chairs with shims taken from the stock regulator to get where I wanted to be, but here's a shim pack recommended by nvreloader
https://www.zoro.com/precision-brand-arbor-shim-assortment-25120/i/G2234635/#specifications

Thanks Jason

Didn't you post once about a certain stack arrangement to sorta start with?
Something like this: ))()()()()(( 
Or something along those lines??

Thanks
Ray

[nervoustrigger]

For the setpoint you're seeking, just stack the 0.032" Bellevilles in series until they fill the shaft of the regulator spool (i.e. until they reach the small O-ring).  The last one you add needs to be concave side facing out:

[small O-ring] )

So if you go to add the last Belleville and it's turned the other direction, take one off the opposite end of the stack.

Series just means the washers are alternated back to back like this:
) () () () () () ( 

As opposed to nested in parallel like ((

Assemble it and check the output pressure.  If it's too low, add shims until you hit your desired setpoint.  If it's too high--which is unlikely in my experience--remove one of the washers and check it again.

[ray1377]

For the setpoint you're seeking, just stack the 0.032" Bellevilles in series until they fill the shaft of the regulator spool (i.e. until they reach the small O-ring).  The last one you add needs to be concave side facing out:

[small O-ring] )

So if you go to add the last Belleville and it's turned the other direction, take one off the opposite end of the stack.

Series just means the washers are alternated back to back like this:
) () () () () () ( 

As opposed to nested in parallel like ((

Assemble it and check the output pressure.  If it's too low, add shims until you hit your desired setpoint.  If it's too high--which is unlikely in my experience--remove one of the washers and check it again.

Yes sir, thanks
I appreciate it.
Ray

[dan_house]

ID be more worried about what it does to accuracy ......  power can be adjsuted and or compensated for, but if lt loses accuracy, why bother?

if it were me, Id buy anohter barrel, chop then install it and see what ahppens....

[ray1377]

ID be more worried about what it does to accuracy ......  power can be adjsuted and or compensated for, but if lt loses accuracy, why bother?

if it were me, Id buy anohter barrel, chop then install it and see what ahppens....

Well I hadn't given that alot of worry so far.
I've had the 12 inch barrel on some of my other Crosman guns before and its pretty accurate.
Now I do know the longer barrel on there now is "REALLY" accurate.
But since you've brought it up, I haven't given any thought to what "increasing" the pressure might do for accuracy.
I do know some pellets like to be shot slower than others for good accuracy downrange.
Thanks Don for your input.
I may have to just dive right in and change reg pressure and barrels and see what happens.
Thanks
Ray

[Ribbonstone]

"Bass-Awakwardws adivse:


I'd urge you to do the tuning mods first (HPA pressure up/ and whatever spring/portintg mods you want to do, get it up to 7.9gr. @ 830-840fps with the full length barrel, then cut the barrel back in length until you get back tyo 780fps (10.6 foot pounds)...might be 14"....might be 12"...but if your aim is to keep the same energy/trajectory as the long barrel...found it better to start  by speeding up the long barrel.