Spring Bolt Action Piston Head

Good day! 

Today i`m gonna share about some different design of BASR piston heads plus how they work, and also how to optimize them for better performance.As can bee seen above, there`s 4 design i will include in this post (from left to right): 

1. Suction Cup Piston Head

2. Ported O-Ring Piston Head

3. Singleport O-Ring Piston Head

4. Stock Piston :D

Now let`s take a closer look at each design !

1. Suction Cup Piston Head

This design consist of single rubber cup, as we can see, there is a little pit separating middle portion and thinner part around the edge. When piston moves forward, air pressure will enter this pit, and then causing rubber edge to expand, creating airseal between piston and cylinder. The good things about suction cup design is there`s no need to replace anything for maintenance, just clean and lube. This design usually seen on APS2/APS96 and some other models upgrade piston. 

2. Ported O-Rings Piston Head

This design consist of piston head itself and separate rubber O-ring. Aside from circular gap where O-ring drops in, you can notice several small holes on top of piston (may vary on different brands). The way it works are pretty simple, as the piston move forward, air pressure will enter from ports/holes towards O-ring`s chamber. O-ring inside piston head will then expand and create airseal between piston and cylinder. Usually you might want to replace the O-rings periodically to ensure it`s elasticity (more elastic, better), also during major re-tune you might also spray ports/holes from top of piston to clean them up, leaving no residues that can interrupt airflow. Afterwards you can do some experiment with different size/thickness/material of O-ring for better airseal (or just stick with good stock one). This design usually can be found on aftermarket piston for VSR/BAR series and some other rifles. 

3. Ported O-Rings Piston Head

This one is basically same as above, the only difference is port/hole position. I personally never used this type of piston, but im sure enough there`s no noticeable difference in performance as long as your O-Ring works properly. Also lately there was some manufacturer using this design on their upgrade product for high-end rifles (Beta Project M200, M24) and yet having negative reviews on their products, so it`s doing the work just fine. Maybe i will give it  a try if there`s any after market piston head for more common VSR/L96 rifle using this design.

4. Stock non-Ported Piston Head

Well, nothing much to say about this last one, instead of utilize airflow generated from piston move, some of stock piston just rely on tightness of O-Ring against Cylinder wall to produce air compression. Actually it works, but leaving many air escape on progress. My suggestions, lube O-Ring properly, make sure cylinder always clean to ensure a good compression, but if u have some budget, aftermarket piston head seems to be a best option.

Personal Thought

I`ve built many BASR until now, from what i found, Suction Cup Piston Heads always gave most satisfying result most of times. O-Ring Piston Head  are actually good as well, but sometimes the package comes with faulty O-Ring(s) or it just doesnt provide good sealing, leave me no choice but to replace it and do trial-error over and over again. I highly encourage the use of Cup design for its simplicity, but if you`re ok with trial-error things, don`t bother to try the other design to achive better air-seal.

That`s it for today, please leave comment if there`s any question,suggestion, etc. 

Pardon my bad English grammar if you spot some :) .

Happy Weekend!