Piston heads ?

Which piston head should you spend your hard-earned money on? Aluminum? Polycarbonate?

Aluminum vs. Polycarb vs. Other

From our experience, we've had great success with aluminum piston heads. However using aluminum piston heads comes at a cost - weight and longevity of the mechbox. While aluminum piston heads are virtually indestructible and will most likely outlast most of the other parts in your mechbox, any aluminum piston head will weigh more than any of its comparable couterparts. This is a serious consideration especially if you are attempting to build a gun with a very high rate of fire - you need to reduce the weight of the piston as much as possible.

Another consideration is that because aluminum is very rigid and hard by nature, it absorbs very little energy upon impact and instead transfers all of that energy to the point of impact - in this case, the front of your mechbox or the piston body itself - we've blown up our fair share of Modify pistons in our day. While the gearbox is not much of an issue on V3 mechboxes, it is a serious fear and concern for those with V2 mechboxes. Adding a Sorbo Pad in this case does help tremendously.

Moving onto Polycarbonate piston heads - while being extremely lightweight their brittle nature does not handle imapcts very well and most users will find themselves with shattered piston heads after extended hard use. Also if you have your eye on a piston head, look at that manufacturer's aluminum piston head. If they both share the same shape, it's a safe bet that that manufacturer re-used the same mold for the polycarb head. A design that works for an aluminum head might not work very well for a polycarbonate head - case in point the Guarder red piston heads. They were infamous for shattering at high loads because the engineers at Guarder failed to realize that polycarbonate and aluminum have different impact properties - who would have thought?!!

Lately, other piston materials have popped up that are of note. POM (Polyoxymethylene) piston heads have become wildly popular lately because they seem to have a happy medium of properties between the durability of aluminum and the elasticity and energy-absorbing abilities of nylon. We've had great success with these piston heads at both high ROF (>35rps) and high FPS (>460fps) setups for extended periods of time.

Bearing piston head or non-bearing?

Having a bearing in front of your piston head helps the spring to rotate more freely during its stroke which could lead to more consistent FPS. However leaving the bearing inside your piston head does increase the mass that has to be moved per cycle so it affects rate of fire greatly. For a high ROF setup, we will typically remove all but one metal washer in the piston head to lighten the mass of the piston.

Piston compression

Most stock piston heads come with pretty crappy piston head o-rings, so sometimes it pays to kill 2 birds with one stone and upgrade your piston head for not just more durable head but also the precise o-ring that'll give you a better compression. After all, better compression equals higher FPS and better shot-to-shot consistency.