[e-luder]

I pretty much understand the blowback now, but does the floating valve "push" the gas into the chamber? From what I understand, gas won't go in a direction unless you propel / force it.

It doesn't "push" it per se but mainly direct it to where it needs to go. The push comes from the blowoff valve on the magazine. Essentially, your magazine is like a can of air freshener. You press a button and the fresh scent of wildflower or whatever escapes from the can. The same principle applies to the magazine.

Also, how does the piston head catch the gas? And how does the o ring function?

As I stated above, the piston head is essentially a sail. When the floating valve closes, the piston head is there to prevent gas from instantly escaping the loading muzzle assembly. [HINT: Look up the physics involved as to how a sail moves a sailboat and you'll understand better.]

Here's an analogy:

Hang a towel in front of a fan and see how the towel behaves. Do you feel air coming through? Obviously not. The piston head acts the same way. The piston head is the towel. So suppose we took the towel off the fan. Now would you feel air? yes? Good. So suppose we remove the piston head from the BBU. Do you think that we will get the same "blowback" as we would if the piston is installed? Do you think we would get ANY "blowback" at all? Probably not.

How it catches air? It just sits there. Waiting. Watching. Like Sauron. lol.
There's nothing special about HOW it catches it. The piston head just gives the channelled air a surface area to blow on.

And how does the o ring function?

NOTE: This is only applicable on the STOCK piston heads. On the aftermarket ones, it has a different function.

So let's go back to fan analogy. Remember how the towel behaves while it's hanging??? It will be blown away right and flap around, right? Suppose we put the something hard in front of the towel, like the back of a chair of something. Does the towel still flap around or does it stabilize itself by using the chair for support?

It stabilizes. That's what the O-ring does on the piston head. Gives the sail more stability and stregth. The O-ring is the chair, BTW.

So with the magazine issue is it supposed to be with the slide on?

Yes.

What brand of magazines are there and what do you recommend?

Tokyo Marui

I took apart my hop up unit, the bucking is fine but seems to get really compressed and mushed when the screws of the unit are tightened. When you look at the bucking on full hop from the barrel, it is kinda lopsided. Is it supposed to look like a flat type bucking, or a u shaped like a concave?

I assume it will be lop sided in the stock bucking. Both of my WE Glocks show the same thing. This is how the bucking imparts the spin the bb needs.

But there should be equal force between the two nubs on the hop up clamp. I tweaked mine to have this. I found that for WE bucking to achieve a perfect seal, your bucking should curve around the BB.

And how tight you put the clamp on will impact how much spin you have on the BB.

Does this mean I need a new bucking?

Check to see if you didn't tear the bucking when you put it back together first.

...and make sure you put everything back properly.

One thing you can do is to tighten the the hop up even more. THere is a clamp on top of the hop up unit that applies pressure to the bucking. Try bending it downwards towards the bucking while the hop-up is off. But not too much because if you do, you will overtighten the grip the bucking has on the BB. You want it to be just right. Then crank the hop up to eleven and see if it made a difference.

The reason your bbs are rolling out is because three reasons:

1). your bucking is torn
2). Your hop up is not tight enough and thus loses a tight airseal.
3). you lubed the bucking accidentally and the bbs are "slipping" through.

Check everything there first before buying a new bucking.

Have you checked what diameter the barrel is?

All of my stock WE inner barrels are measured to 6.03 Tighbores (at least the ones that come from Evike).
I can only surmise that it may have been the standard for their Glock line. But seeing your inner barrel, it could be different. Mine had a blue coating on the exterior but yours is brass colored thus yours may be different.

They usually mark it on the side of the inner barrel anyways. If not, go buy a ruler and measure for yourself.

Everything in your pictures look like they are still good shape. But to be honest, they are in poor lighting condition so I may be wrong.
Just buy a new piston head if you are worried it's cracked. Buy a metal DYNA one. Works great.

You can fix your magazine catch problem by doing this:

Get a Coke a can. Cut a piece of the side off. Now cut the piece to match the shape of the groove on the magazine catch. Then superglue that badboy in place. Make sure it is as flat as possible.

Do a trial run by stacking as many pieces you need before you glue them altogether. That should create the packing you need to raise your magazine up higher.

The best part is... it only cost you a can of Coke.