Nine Ball Power Spring Upgrade
Test Bench: TM MP7A1
Chrony: Guarder Speeder 2000
BB's: KSC Perfect .20g
Mileage: approx. 500 BB's
Other modifications: none
Pre-upgrade chrony results (7.2v battery at full juice):
Post-upgrade chrony results (7.2v battery at full juice):
Avg. Gain 16.4 fps.
Nothing to brag about.... would be interesting to see the results after the spring has seen some heavy usage.
I should probably point out the disassembly/re-assembly of the MP7A1 was no easy task. If you think GBB makeovers are difficult, you should probably leave this to a professional.
I found the MP7 to be considerably more difficult to work with than any of the GBB's I've changed over, thanks to the tight spaces in the gun and the midgetbox Marui designed for this gun.
NOTE: When removing the midgetbox, gently guide the wires through the opening as you slide the midgetbox from the rear of the gun. The wire contact points on the motor are extremely flimsy and could break off easily with the slightest force or impact. The same caution should be used when running the wires back through to re-install the midgetbox. Running the wires back through the opening was a task by itself. :banghead:
Definietly not a mod-friendly gun, and judging by it's power and potential it's more of a collector's piece than a skirmish gun anyway.
But if you're stuck on (with) the MP7 and want some extra fps, the Nine Ball Power Spring is one option for you.