Re: Recon class is not receiving the full amount of bullets.

I guess that's because you don't take out your magazine to fill it. You will always have a maximum of two extra magazines.

The amount of ammo you carry at "max" when not reloading first, is in for instance the Enfield, 20 bullets(the two magazines) + bullets you already have in your gun/magazine.

So if you have 3 bullets left in your magazine, you don't swap that out when you refill, but you swap out/refill the magazines that you don't carry in your gun. Therefore you will end up with gaining additional 20 bullets, and not 27. 

These details make the game more challenging and realistic 🙂,

I don't know why you only can carry 20 bullets sometimes, though. That might be a bug.