Sorry, but we need more information on the term "round barrel gun".
Red Ryders are usually loaded with BB's through the slide door under the barrel near the end of the barrel.
In modern times, the t80 and t90 both require its barrel lifted the t34 also required it
The first guns were cannon- they were rather short, and looked like a barrel- a hollow container, round and long.
To reload your gun in the game simply press 'r'. So easy a caveman can do it.
there is a button at the top of the screen that says reload click it to reload
When th ammo in the sentry gun reaches 0, then you can reload it. To reload, walk on top of the sentry gun and press the F key. I'm not sure if you can reload it when there is still ammo in it though, but you can try. When you reach the rank Colonel, once you set up a sentry gun, you will have double ammo for the sentry gun, and you can reload it faster.
If a round is not fired and then ejected, nothing comes out of the barrel.
shoot outsid the screen that should reload your gun.
Unfortunatly yes, the barrel can contain 6 dart/shots, and has to have the slide pulled after every shot, and fully reloaded after every six shots.
Chamber
There is a black area that can open
you have to get the USP pistol and empty the clip and when you reload it will "flip" the gun