how do i refill alt ammo?

[GlacialSkyfarer]

yeah.
i just want to know that

[Mailer]

Alternative firing modes exist for multiple weapons. If you are specifically referring to the Half Life 2 weapons, the AR2 uses "Combine Balls" whereas the SMG uses "SMG Grenades", both of which are found under the "Entities"-tab, under the "Half-Life 2" category(?)

[GlacialSkyfarer]

i mean with commands
ar2 is refilled with givecurrentammo but the others wont work like that

[Mailer]

In that case the simplest solution would be to use...

impulse 101

...which will refill ammo in every category and give you any such weapons that you are missing. It also requires...

sv_cheats 1

...prior to being run.

Just in case you don't want to deal with having a bunch of weapons resupplied alongside the SMG-Grenades, there is also another more convoluted but fine-adjusted way to give yourself specific ammo types:

lua_run player.GetByID( 1 ):GiveAmmo( x, "[ammo_type]", true/false );

player.GetByID(1) will most likely always return you as the player when in singleplayer, so be otherwise careful when running this lua-stroke in a multiplayer session with several people connected.
GiveAmmo() will give you an x amount of ammo of the type [ammo_type], where you can finally choose true/false to hide the pop-up notification when receiving said ammo.
For the names of different ammo types, use this* page.

So if you were to, for example, give yourself 10 SMG Grenades loudly, you could run the following in console:

lua_run player.GetByID( 1 ):GiveAmmo( 10, "SMG1_Grenade");

Hope this helps. Feel free to look more into the GiveAmmo() function as well**.

* https://wiki.garrysmod.com/page/Default_Ammo_Types
** https://wiki.garrysmod.com/page/Player/GiveAmmo