Tuning the JP SCS

[Silverscooby27]

Can anyone provide an explanation of how to tune this SCS, in other words, how does the system work, what does changing the weights do, the springs and when do you want to change one vs the other and why? I’m so confused. Thanks 

[Tampa-XD45]

You may want to check out the SCS videos on JPRifle's YouTube channel: https://www.youtube.com/user/JPRifles/search?query=scs

And some real world examples here: https://forums.brianenos.com/topic/273407-tuning-jp-scs-system-for-least-dot-bounce/

[Darqusoull13]

Yep, both great links @Tampa-XD45

If this is for the Short Stroke we discussed I'd shoot what you have first, then disassemble the SCS and swap to 2 tungsten, 3 steel weights and try that. You can swap more tungsten if you want it softer or try more steel if you want a faster cycle. 

[rowdyb]

I have all the different springs and might fool w some of them as well...

 

But for now I really like 4 or 5 tungsten 

[bgary]

I'm using the stock spring and 5 tungsten weights (basically the same as their 5H5 model), it works great for me.

[bobby hated]

On 8/1/2019 at 8:26 AM, Tampa-XD45 said:

You may want to check out the SCS videos on JPRifle's YouTube channel: https://www.youtube.com/user/JPRifles/search?query=scs

And some real world examples here: https://forums.brianenos.com/topic/273407-tuning-jp-scs-system-for-least-dot-bounce/

That was the most uninformative video I've ever seen lol

 

Thanks for all the comments much appreciated! Looks like I'm gonna go SCS with all steel for lowest OA weight and fastest possible cycle rate. I could care less about recoil impulse or the dot bouncing. 

[Aircooled6racer]

Hello: You have to balance the spring and the weights to the load you are shooting. Too much weight and it will cycle slower and hit harder. Too much spring may cause short stroking and feeding problems. Too light a spring can cause feeding problems since the bolt hits harder at the back that may cause double feeding or ammo to jump out of the magazine. If you are shooting factory ammo I would leave the setup alone or go a little heavier on the weight. If you are shooting 125PF loads I would lighten the weight and the spring so you get two bullets stacking on each other at 7 yards. Hope this helps. Thanks, Eric

[bobby hated]

3 hours ago, Aircooled6racer said:

Hello: You have to balance the spring and the weights to the load you are shooting. Too much weight and it will cycle slower and hit harder. Too much spring may cause short stroking and feeding problems. Too light a spring can cause feeding problems since the bolt hits harder at the back that may cause double feeding or ammo to jump out of the magazine. If you are shooting factory ammo I would leave the setup alone or go a little heavier on the weight. If you are shooting 125PF loads I would lighten the weight and the spring so you get two bullets stacking on each other at 7 yards. Hope this helps. Thanks, Eric

Thanks I'll tune my load. My Proddy load is 130pf with a 124 plated and N320. Prolly have to cut a few grains off the powder load, but I prefer a high cycle rate to flat shooting on the continuum. 

[Aircooled6racer]

Hello: If you are using the JP 4 weight SCS try 3 steel and 1 tungsten weight with the green spring. I am shooting 124's with Clean Shot at 131PF. It will cycle faster than I can pull the trigger. Thanks, Eric

[impact]

When increasing the spring rate, what effect do you guys notice? Is the forward impact of the bolt/buffer causing the muzzle to dip further or probably earlier as spring rate increases and is there a point where you feel a bolt can hit too hard, probably causing harmful deformation of the boltface and chamberwalls?

[rowdyb]

I'm gonna try 4 tungsten and 1 steel today with going from the red  yellow spring down one step.

[rowdyb]

Going just by feel, shooting 147s with fast powder  I'm really really liking 4 tungsten and 1 steel weight with the middle weight half red only spring. 

 

I'd totally suggest making changes to get what you want