The piston could also be Angel brand
The tappet plate and cylinder sounds like the stock Classic Army ones.
I recently worked on a Classic Army SR-25 that was exhibiting the exact same problems you were having. I attributed all issues to really shitty stock Classic Army parts.
The cylinder compression test concluded that... well... there was no compression because air was just firing everywhere. First thing I did was swapped the piston head and cylinder head to a Systema silent head set and the gun went from shooting anywhere from 80-180fps and after the silent head set was installed, it was shooting about 330fps consistently.
But the power was still pretty low, considering the spring shot 425fps in my P90 test platform.
I did the compression test again and checking for air leaks and realized: Classic Army air nozzles are the WORST designed air nozzles in the entire industry. I don't know who the knuckle head engineer is who designed them, but they have slots cut in to the side of the air seal nozzle, so guess where the air goes when the gearbox fires? That's right... NOT out the front and down the barrel. It fires all around the hop up chamber and out the magwell.
The shitty thing for my client was that his SR-25 pretty much has impossible to find and unique parts. The only "proper" air seal nozzle you can get for the SR-25 is the G&P one, and unfortunately, is only available with their gearbox kit. If all you need from that kit is the air seal nozzle, that's a $250+ air seal nozzle...
Anyways, the client just wanted the gun to work and was willing to pay for the air seal nozzle. Once it was replaced, the gun was shooting 380-390fps at a somewhat okay consistency. Not as efficient as I'd hoped, but considering the amount of time put in to the gun just to get it to where it was, my opinion on Classic Army guns remains the same - GARBAGE.
Whoever designed some of their parts deserves to get full auto'ed with a hi-cap. Not from a Classic Army gun, of course... because they wouldn't be able to put out enough power to teach him a lesson. har har harrrr
Quote:
Originally Posted by Crunchmeister
Yeah, parts don't all fit like they're supposed to. I've been discovering that myself as I'm starting to delv into the upgrade thing myself.
I upgraded my CA M15 rifle yesterday. I installed a Systema red polycarbonate piston, Systema spring guide, and a Systema silent piston head / cylinder head set. Also threw in a Prometheus MS110SP spring. BTW, my stock CA tappet plate is yellow as well. Looks like I'll be having to replace that as well soon. It's showing some wear on its edge where the cam from the sector gear connects with it. Ugh... more money to spend on this gun. lol
Now, initially, there was a fit problem. The stock CA cylinder seems oversized. I couldn't get ANY compression with the Systems piston assembly. When I blocked the nozzle with my finger and compressed the cylinder, all the air would leak out from around the piston head o-ring and out the back of the cylinder. I had to swap the Systema o-ring with the stock CA one in order to get a positive seal. It does work great with the CA o-ring though. I get what appears to be excellent compression now.
Now I test fired the gun, and it does appear to hit quite a bit harder than it did while stock. I'll be receiving my chrony on Monday or Tuesday, so will be able to give some numbers then. But I was able to get results similar to those with my JG MP5. I can easily punch through the bottom centre and almost through the inner edge of a coke can. I'll post some numbers in your Prometheus spring thread when I get my chrony.
Good luck getting the gun working.
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Systema silent head sets require you to remove the o-ring and give it a good stretching out as you apply lube to it. It's part of the break-in process of the o-ring, but when done properly, the head sets provide a great seal - even in CA cylinders.