[Flatlander]

Background:

Purchased a slightly use CA SPR which chrono'd 285fps when I got it. I was told it was a prom 100 spring so it is was only a touch low off the bat. I had to tinker with it and see what's inside and it's never been the same since...doh!

The gun is chrono'ing anywhere from 90 fps to 150fps. Occasionally I can get it to 230ish with the 100 spring. So there is some huge losses here that I cannot figure out for the life of me. The gun cycles, feeds and sounds great otherwise.

**Cylinder/nozzle compression tests were good. Plugging the inner barrel (exit end) and BB feed tube while blowing through the nozzle entrance of the hopup unit showed no leaks.

Parts:

**found a metal piston head and systema red piston originally so I swapped those out immediately.

- 7mm CA gearbox w/ stock gears
- Upgraded full cylinder (unknown brand)
- TM piston
- Unknown metal bearing spring guide (systema?)
- Upgraded brass tapered cylinder head (appears to be systema like the silent head)
- Looks like the stock plastic nozzle

What I did/tried:

- 3 springs: prom 100, stock TM, prom 90

- 3 rubbers: stock CA (?) that came with it, guarder clear and systema

- 2 hopup units: 2x stock CA and stock G&P

- TM piston head and Prometheus bearing POM heads

- Swapped upper receivers from my CA m4 with no change (m4 shoots great)

- Using the SPR upper on my m4 lower gives a 20fps boost (405fps) so it appears the hopup/inner barrel on the SPR is in good order.

- Hopup and inner barrel slide freely into the outter barrel and spring back

- Loosened full stock screw which attaches to the spring guide

- Reassembled the lower parts in different orders (ie. trigger pin, pistol grip, rear body pin)

Problem Areas Assumed to be Eliminated:

- Hopup unit, rubber and inner barrel

- Compression internals: good seals but only the piston head was swapped for comparison



So I am completely stumped on this one right now. My guess would be some sort of weird alignment issue but I haven't a clue. Any suggestions are much appreciated!