I recently purchased a stock CFX and plan on doing a tune. Question is do I buy a spring kit or a gas spring kit? I would like to do some FT shooting with it if possible.

Any opinions greatly appreciated

try a lube tune and spring guide with Delrin tophat from "Rich in Mich".

After working on mine extensively I concluded a soft tune with the stock spring and a tophat that didn't exceed 15 grams in weight gave the tamest firing cycle; not the higest velocity though the most accurate for me, about 12 fpe. The stock seal is no where near as good as Jim's but it's fine to get to know the particulars of tuning the gun and take the abuse a seal gets with the first unfamiliar tune. Better to find out you forgot to deburr a hole or slot and verify your tune with that seal, if you like the results get the JM seal; you'll probably have to size it a hair.

You'll probably relize the gun needs some more weight added to the stock. Most people just put their favorite slurry in the stock after removing the buttpad, the stock is hollow.

I can't comment on a gas spring\ram as I have no experience with it's firing behavior in that gun.

Gas ram every time for me.

After a smoothing and deburring, no lubes for a spring necessary on the Gas Spring.Maybe just some moly on seals and piston.
It has a quick crisp firing cycle, exactly the same every time. Mines in .177,gas rammed, gold trigger.
The other is a RFM .20 conversion I picked up last month on the Yellow with JM springs and parts,RFM trigger parts, normal spring lubes performed; it's also smooth as all get out. I haven't chronied either, but neither one is a disapointment.

Gas spring form Pyramyd is $109.00 just for the spring, then you'll have to install it yourself or send it to them to do it.

AA Skiff has a tutorial on the install: basically remove the piston,and spring and guide. Remove the guide portion leaving the plate, slightly drill an indention for the piston rod of the gas spring to rest in in the remaining plate of the guide(spring guide), then slide the gas spring into the piston and lube and reassemble. No Tar!

Can't quote RFM's price for install kit but I know it's on his site. It's a Very smooth firing cycle, not crisp or sharp, just a nice thwap!

The beginning few inches of the cocking cyle seem non-existent(RFM), then some effort. That is: easy then harder to compress.
The gas spring is 100%: hard then hard, the same from start to finish on the cocking cycle.

Hank
"Semper Fi Mac!"
1st Force Recon Co. U.S.M.C. 1986- 1992
E.O.D. MU-7 U.S.N.R. 1993-1996
1999-Present-U.S.A.R. Drill Sergeant