NOTES FROM LUKE: The Apollo Spring cut from a K26 is a 3.7" custom made spring that offers a roughly 120FPS average compared to the stock average of 86FPS. This mod is relatively easy but definitely not for kids! The Strong-Prime spring is slightly longer than the stock spring so make sure when reassembling the plunger tube that the bottom internal gear rail is pushed all the way to the back in order to catch the last gear. You can lose all the little plastic pieces inside the plunger tube except for the catch and rods.
For extra FPS consider adding a thin strip of electrical tape under the o-ring of the plunger in order to create stronger seal/more air pressure.
-Medium difficulty on installation -Both ends are flat/squared -Around 120FPS can be expected (more if you create a tighter o-ring seal)
SPECS: -Custom made compression spring, -Spring-Tempered Steel -Made in the USA of USA steel -Square/flat ends