Hello all!
Ever since discovering the very VERY small market for spring trishot upgrades, I had been looking into upgrading one for the hell of it. I was originally going to be throwing parts into a DE/UTG M3, but upon the release of the CYMA full metal 870, I thought it to be a much better, solid platform to throw money at.
I recently picked one up for myself, the short barrel/full stock version, and figured I would do a write up on it to some degree, maybe help others to know what they might be buying. I am by no means great at reviewing, but I will be going into the internals, comparing it to other potential parts on the market, any recommendations, etc, so lets being:
Lets start with externals.
I would compare the size to the TM gas 870 if I could, as that would be a good place to start for external sizing and possible after market externals, but I am unfortunately unable to at the moment, but will update if I ever get the chance.
Metal parts:
-Receiver
-Mock Bolt
-Trigger and trigger guard
-Shell door
-Pump arms
-Pump guide
-Outer barrel
-Shell tube
-Shell tube cap
-Front sling mount
Plastic parts:
-Orange tip
-Stock (with rubber butt plate)
-Part that holds the shell tube to the outer barrel
No creaking or bending. the externals are very solid together. The pump wobbles just the slightest bit, but that would be expected in my mind. With each pump, about half way cocked, the mock bolt (can't come up with the proper term for it on a shotgun) moves back, and then returns when you slide the pump back forward. Nice little feature, doesn't hinder performance, but unfortunately doesn't reveal an adjustable 3/6rd slider like the TM 870.
Shell door release is located on the right side, to the side of the trigger guard. The shell door is spring loaded, so when you pull the release, it generally pops the shells out with ease.
Safety is located behind the trigger as a button that pushes from side to side. Right side safe, pushed to left is ready to fire.
Lets start the disassembly:
Pry the rubber butt plate off of the ridge on the stock. Underneath, you will find a hole with a Philips head screw, and a smaller Philips head screw below that. You will want to unscrew the larger/top screw. This will release the stock from the receiver.
For the pump, you will need to unscrew the shell tube cap. This was rather tight when took mine off. Remove the cap and front sling mount. Remove the 2 Philips screws in the bottom of the pump. The pump should now slide straight off the front.
The trigger guard is removed with 2 pins (Usually screws in other trishots). One just behind the shell door, near the bottom of the of the receiver, and the other at the bottom, just about where the stock attaches to the receiver. These pins have friction parts at their center, so it does not matter which side they are punched out from. Once the pins are removed, the trigger guard can be removed with a little wiggling.
With the trigger guard off, you can remove the trigger, secured by 2 Philips screws. Set that aside.
To remove the receiver, all you need to do is remove the 2 screws at the bottom rear, 1 on each side, and the metal outer receiver should carefully slide backward and off. Be careful of the anti cocking lever popping out as it is spring loaded and did so for me. This part is there so that you can't pump more than once. For some, they remove it to allow for use with certain hop up and barrels that allow 6 bbs to be shot effectively. No modification, just simply remove. I will cover the parts and what is done later.
Moving back to the pump area, you will find (what I called) the pump guide, a metal piece with 2 Philips head screws, 1 on each side. Remove those screws and slide that piece forward. Doing so will reveal 4 more Philips screws, 2 on each side. These hold the outer barrel and shell tube to the guts of the shotgun. Remove and set aside.
On the underside of the outer barrel, just in front of where the shell tube stops, is a 1.5mm hex setscrew. This holds in the barrel spacer that keeps the barrels aligned straight. I find it is easiest to take this out to make reassembly easier.
And lastly, are the 4 Philips screws that hold on the pump arms, 2 on each side. Remove those, and the whole front end should slide off.
You should now be left with the inner mech box of the shotgun and the barrels.
Opening the mech box,:
Have it oriented with the barrels pointed to you right, so you are facing the right side of the gun.
There are 2 small Philips screws that hold in the hop up, 1 on either side, where the barrels attach to the mech box. Remove and set aside. The barrels/hop up assembly will not come out at this step, so don't try, you may break something.
If the anti pump latch/spring didn't pop out by now, take it out carefully as to not lose the spring and set it aside.
Pry the spring for the shell door out of the mech box shell. One less spring to fly if it pops open.
Continue on to remove the 12 Philips screws around the shell. Once all screws are removed, you can carefully open the top half of the mech box shell.
Now we finally arrived inside the guts. Thoughts are as follow:
First off, unlike ANY clone trishot I have ever owned or opened, there is actually lube! The pump arms, piston shuttle, piston heads, main/return spring, and the internal rails of the mech box all had that green snot-like lube, signature to CYMA. Any lube is better than none, and I am impressed with it.
A number of the internal parts are a bit more reinforced than the clones I have worked on. The parts use a fiber reinforced cream colored material, similar to the pistons in CYMA AEGs. Being made of this material, I have better faith in the durability of the parts, which consist of:
-Spring guide(though I was disappointed to not find a basic metal washer to aid in wear prevention from spring rotation)
-Piston shuttle
-Piston arms
-Cylinder
-Piston shuttle catch (part of trigger components)
-Intermittent trigger component(for lack of a better term)
And a different type of dark colored translucent plastic, not your standard ABS found in clones, was used for other components, such as:
-Hop up unit
-Hop up housing
-Barrel locking c-clips
-Shell door catch
-Bb feed plate
-Bb feed lever
-Barrel spacer
I am unsure at this point in time if there are any benefits to this material as opposed to the other alternatives. It may be a bit more resistant to wear, and less likely to crack, but time will tell.
Biggest bonus and item I am most pleased with; brass barrels. They are much nicer than the crappy aluminum found in clone trishots. They have a very nice internal finish to the eye. Can't measure the microns of consistency, but they measured to be about 6.08 in diameter at the standard trishot 297mm length. No crown which I find a little disappointing, but that's not really a big issue, and can be modified later if I want.
The buckings have a very prominent mount, leading to very nice hop with whatever weight you might use.
The piston heads, compared to clones, almost seem to have an extended center portion, that helps to absorb shock, as well, has very nice seal with the cylinder. Each cylinder of the CYMA is approx. 13.8mm in diameter, as opposed to clones that were closer to 14.3mm. That is near the edge where I could measure, but for clones, I would say the cylinder tapers tighter toward the nozzle, as in testing compression, the piston head doesn't even start to catch until halfway through the cylinder. Whereas the CYMA starts great compression right from the edge.
The cylinder itself, while appearing to be made of the fiber reinforced material, has a very smooth finish to it, inside and out, which would lead to a much better air seal.
That will be it for now. If anyone is curious about anything, feel free to comment below, and I will add to my thread. When I have more time I may also clean up and organize the post.
