Swapping ported cylinder for 100%

So I got me a 2nd hand LDT HK416 and saw that the guy’d upgraded the barrel (though it was in backwards, poor bugger) and I also saw that the cylinder is ported. Looks like maybe 80%.

My question is: Is there any harm in putting in a 100% cylinder? And what IS the proper cylinder volume/barrel volume ratio? I know Low Guido dropped some knowledge on this, but sometimes the science is beyond me.

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The main number/ratio I often read about is 2-1. From my understanding, a ported cylinder is most important on very short barreled blasters… such as a vector.

The piston head has X amount of holes to let air in for the next charge… if the barrel is, for example, 30cm… then a full charge is more likely needed. If the barrel is only 2" long, there is no need for a full cylinder… which takes time to pull through the holes in the cylinder head… so, often, a gel or 2 will get sucked back into the cylinder and get mulched in there.

When the piston is being pulled back, with a port, the port will be opened and then there is no suction to pull a gel into the cylinder thru the nozzle any more.

Having a ported cylinder in something with a long barrel may mean the cylinder doesn’t get enough air to push the gel all the way out of the muzzle…

All just my own observations…pop

Long story short, if it were my blaster, and the barrel length is over about 2750km, I would not use a ported cylinder… at least, I would try using a 100% cylinder and see if it is an improvement or not…:sunglasses:

2750 barrel is indeed a very very long barrel :rofl:

Every blaster I have currently is using ported cylinders 75% and 80% and barrels from 250mm through to 360mm , the 360mm one is using a 1.25 unequal spring and is doing 360fps and is full metal box and receiver yet it is as quiet as a mouse and zero piston hammering.


2.7m barrel thats huge. Will def need a 100% cylinder for that, maybe even 2 or 3 cylinders together.
Also having to much cylinder volume compared to barrel length means there is still air pressure behind the ball after it exits the tip causing it to be pushed around and not be accurate. Ideally you want the puff of air to be exhausted just before the ball leaves the tip. You definitely dont want it running out of puff half way down the barrel other wise the plunger is then sucking the ball back down the barrel

There, I edited it to make it correcter…laughing%20(1) Flipper rofl

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Geez, excellent, excellent advice guys, thanks so much. Damn, there’s a reason I come HERE for help, and not some FB group where you have to filter out the snark and the ego.

I’m going to measure my cylinder (properly this time, not just tip to tail like a genius) and watch my Low Guido again and work from there.

Thanks again guys.

PS - Calcifer, where’d you get your name from? My son named one of our rabbits Calcifer years ago and I thought he invented it from a combination of Calvin and Lucifer (whom he felt the rabbit was a combo of).

From Howl’s moving castle… Calcifer is a fire demon koolaid

Excellent movie… pop


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I am really only a fire demon after too much Mexican… laughing%20(1)


HA! Nice!
I too, am a post-Mexican Fire Demon, but that movie was one of his favourites as a little one, so it probably made it into his subconscious and he didn’t realise.

Also, put alloy barrel in the Vector, bit long, and tested mags through it while cutting down barrel bit by bit. Sure enough, after 2 cuts, she was shooting beautifully. So no real science needed, just a Dremel and some gels.


Mild Mexican and Thai are not so bad…


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