Prolite mainspring replacements

[Axel]

Interesting.... Manufacturers constantly make changes over the life of a product but I've never heard of any major valve design changes in the Pro-Lite
it doesn't seem likely that anyone went to the trouble of modifying a Pro-Lite valve very often, either

How different?

[The Inflicted]

Has anyone tried replacing the Pro-Lite's valvespring with a weaker one to see if it improves HPA performance?

[Meleager7]

On the pro-am I used to have , it was only going as high as 240 fps with that velocity choke screw wide open....switching to co2 fixed issue and I could get 280 fps....

[shadow191]

Is there any place that still has the springs? Seems every place is sold out. Would like to try a new spring out first as it's cheaper and easier than going to co2 setup.

I bought mine new in '94 I think so not sure what internals it has. It's interesting that last time it was used on co2, the adjuster was turned most of the way in to keep it under field limit. Now with HPA it's backed out all the way and won't go above low 240's on first shot and it drops to high 220's by 3rd or 4th shot. Also noticed that when I unscrew tank, it's a very muted release of air unlike unscrewing tank from a Spyder. Unless my memory fails me, unscrewing a co2 tank was much more of an event and I had a few tank o-rings fail during removal.

Mostly want to use the gun for nostalgia but if it's too much trouble I may just hang it up on wall. It's fun to use compared to modern guns because it's so much harder to play with - trigger pull so heavy my hand started cramping after shooting half a hopper and it's like 3 ft. long.

[JOESPUD27]

Got a SMG68 spring from a user on MCB. Shoots above 300 now (i had to chrono down) but works fine on HPA.

[BretG]

Another thing that can be done is to boost the output on your HPA tank regulator. One shim on the spring stack will boost the pressure to 900 and this enough to bring up the fps.

[BlindFaith429]

Sorry for bringing up an old thread, but im starting a tear-down on an old Pro Carbine, and will be trying to run it on HPA.

Is it just going to be trial and error to see if I need to modify anything? Or is there something I can look for while I have it all apart?

My spring measures 4.275 when relaxed and out of the gun (I assume I'm measuring thr right spring, the one between the tail-cap and the bolt).

[Chappy]

Procarb will likely shoot above 280 stock unless the mainspring is worn. I would just clean it up and try it out. If it’s low start with a new mainspring.

[Chappy]

Also, procarb takes 98/A5 springs, so you won’t have problem gettings getting them