PolarStar Piston and Spring Guide

[mikemikemike]

If you own a UTG MK96 you have considered upgrading it, to increase your FPS and distance. Many of you have probably opened the gun and many have not. The guns construction overall is very good, however the internals are plastic (See comparison later after parts review and before install guide). The stock internals can just not hold up to the additional power and stress put on the gun. PolarStar has come up with the solution, two brand new products. The PolarStar Piston and PolarStar spring guide.

PISTON


This is PolarStar's new piston for your MK96.

First lets look at the black cap. This is the cup seal and buffer portion. It is a high durometer urethane rubber. It is super durable and will absorb all the force as the piston returns to its resting place after firing. The seal that it forms is super tight, and does not allow any air to blow by.

The blue area of piston is made of 6061 anodized aluminum alloy. In simple terms, the piston head is super strong and will not have the potential of
breaking on you like the stock piston. The best part is that it is super light, I have not actually weighed and compared them, but they feel like they are the exact same weight.

The base is made of stainless steel.

Lastly you will notice the two white rings around the body, these are glide rings made from Delrin. Delrin is a low friction plastic, which is perfect since the piston will be moving back and forth a lot inside your gun.




Spring Guide



Next we have the spring guide. The spring guide is completely made from stainless steel. This is very important because with your upgraded spring there will be more energy being put on the piston guide, which will snap it either right away or after a few shots if your lucky.

Notice the white ring, it is also made from Delrin. What is its purpose? Well this is my favorite part. By purchasing additional rings, you will be able to up your guns FPS and distance. What you are doing when adding additional spacer rings is making the spring longer. This is a cheap, reliable, and quick way to up or down your FPS if you need to for a field event, without having to purchase additional springs.


COMPARISONS
PISTON


As you can see, just about everything on the stock piston is plastic, except for the rubber o-rings. The stock rings are made from crappy rubber and plastic that will break under higher stress.

Spring Guide


Again the stock part is all plastic. It will definitely shatter with an upgraded spring. The PolarStar version is shiny, and indestructible.


INSTALL GUIDE (Some picures are from other forums, credit given. I noticed last minute that these would be more helpful than me trying to explain it)

Installing these two parts was a lot easier than I thought. I am mechanically ignorant but was able to install these so you will too.

1) Make sure the gun is not cocked. Pull the trigger and make sure there is 0 spring pressure on the gun.

2) Now we need to remove the cheek rest. We start by removing the two bolts circled. Once the bolts are removed, simply and gently pull the face rest straight out.
kooster83
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3) Now look where your trigger is. You will see a latch that looks like this (see below). This may feel like it doesn't move but just force it down. If it pops out, just put it back in later.
j0ey2069

4) By pulling that latch down, you have released the bolt. Now pull the entire bolt out of the gun. It should come out easily.

5) Now with a pair of needle nose pliers, carefully twist the top off. The metal is a little soft, so be sure not to mess up the two holes. Twist the cap off. (Lefty-Loosey, Righty-Tighty). When you take the cap off, be CAREFULL, all the parts on the inside could shoot out at you.


6) You will end up with these parts:


7) Now on the bolt you will see a slotted groove down the side. Run your finger all along it, and underneath on the inside to make sure there are no sharp edges. I had one small area that was sharp. What you want to do it smooth it down with either sand paper or a smooth file. If your edges are smooth skip to Step 9.


8) Now that you shaved it you will have metal flaked inside your bolt assembly. Rinse it out with soap and water to get any metal out, as this may ruin your internals. Dry thoroughly. Once it is completely dry re-grease the inside of your bolt. (I use Super Lube- USA).

9) Now that everything is out and clean, its time to re-assemble. Start by placing your new PolarStar Spring guide in one end of the spring. Make sure the white ring is on you spring guide at the bottom. Now place the PolarStar Piston on the other end of the spring.

10) Re-Lube the spring lightly. Also make sure to lube the spring guide, and the the piston head along the rubber and glide rings

11)Take your spring assembly and place it inside the bolt again. You will notice that everything may pokes out higher than it did before. This is fine, just push down the the cap and start screwing down. Again, be careful because you don't want it shooting out at you, and not to ruin the two holes.

12) Once the cap is tight(but not super tight), slide the bolt back into your gun. There is a little latch that will prevent you from sliding it in all the way. Simply take a flat head screw driver and push it down as you slide the bolt back it.
Sorry that the picture sucks, it was either too bright or two dark.

13) Lastly, put the cheek rest back on.