difference between M16A2 and M4 gearbox

[ccama]

is there any difference M16A2 SR16 and M4 V2 gearbox, will a M16A2 gearbox fit other SR16 and M4 receiver
also why do some m4 gear box have a vented cylinder but m16a2 don't have it

[Fingers]

Re: difference between M16A2 and M4 gearbox

Mostly yes. (except ICS split, Systema etc). Just make sure the gearbox is wired to your requirements - ie to the front or the back. M16 & SR16 gearboxes tend to be rear wired as the battery fits in the stock. Some M4's are front wired as the battery fits in the front handguards.

[101stairborne-506]

Re: difference between M16A2 and M4 gearbox

the actuall gearbox casing is the same shape though.

[ccama]

Re: difference between M16A2 and M4 gearbox

I got a systema m16a2 m120 gearbox will it fit to a m4 body

[Fingers]

Re: difference between M16A2 and M4 gearbox

Of course yes, so have I

I meant the Systema PTW gearboxes, sorry for the confusion.

[ccama]

Re: difference between M16A2 and M4 gearbox

thanks, also why some cylinder have a hole (vented cylinder) some does not ? less pressure ?

[seansamurai1]

Re: difference between M16A2 and M4 gearbox

The vent sits at the back, it means it can pull more air in when the piston is doing its compression stroke, but also vents air on its suction stroke, theres less resistance on the piston on its return stroke leading to a possible increase in ROF. Im sure there is another reason for it though, which Im pretty sure someone shall enlighten us too.

[The Keeper of Secrets]

Re: difference between M16A2 and M4 gearbox

It's to do with the volume of air that is actually used.

If you have a longer barrel with a vent, the bb will not start moving until the piston has passed the vent and actually starts compressing air. Thus the distance left for the piston to travel once the bb has begun to move is less. Thus, when the piston has finished, the bb may well still be in the barrel. At this exact point, the pressure on either side of the bb is equal, and any further movement forward by the bb will create negative presuure behind it. This is known as suckback and will rob you of FPS.

If you have no vent with a shorter barrel, air is being compressed immediately, and so the bb starts moving straight away. The bb will most probably exit the barrel before the piston has finished. At this point, there is no air compression in front of the piston and thus a sudden drop in resistance, causing the piston to slam forward into the cylinder head at a far greater speed than it would normally. This can damage the piston head/cylinder head and can also crack the front of gearboxes.

Short summary, get the correct port for your barrel length.

[seansamurai1]

Re: difference between M16A2 and M4 gearbox

so you would say rule of thumb, short barrel=vented cylinder.
Long barrel=non vented?
Just wondering, as my LR300 has a new vented cylinder in it and it has a short(very) barrel in it.

[The Keeper of Secrets]

Re: difference between M16A2 and M4 gearbox

Yes. Get the correct length for your barrel. Use google.

[seansamurai1]

Re: difference between M16A2 and M4 gearbox

Wow, must have been a long day on the forums, wasnt even gonna ask the obvious in this section, just wanted to check my thought for short hand instead of big long story was indeed correct. I apologise if this sounds a little narky, but after my 19th hour working, as Nicholas cage says, Im a little wired, Im a little tired. But your post read a little bit off in my eyes. Especially in relation to some questions Iv seen on the forums as of late and they dont get the "Google it" reply.

[The Keeper of Secrets]

Re: difference between M16A2 and M4 gearbox

My post wasn't supposed to be sarky or anything. It was simply anticipation the question "do you know what the correct cylinder is for this barrel?". Thus the preemptive reply, use google.