Что можно изменить в системе

[m1n1vv]

В смысле? Там нет ничего подобного: http://wiki.sa-mp.com/wiki/GetWeaponName

Невнимательный

[m1n1vv]

Что лучше?

static stock Switch_library(playerid)
{
    switch(mn_weaponid{playerid})
    {
        case WEAPON_COLT45, WEAPON_SILENCED: mn_ammunition{playerid} = 17;
        case WEAPON_DEAGLE, WEAPON_SHOTGSPA: mn_ammunition{playerid} = 7;
        case WEAPON_SHOTGUN, WEAPON_RIFLE, WEAPON_SNIPER: mn_ammunition{playerid} = 1;
        case WEAPON_SAWEDOFF: mn_ammunition{playerid} = 2;
        case WEAPON_UZI, WEAPON_M4, WEAPON_TEC9: mn_ammunition{playerid} = 50;
        case WEAPON_MP5, WEAPON_AK47: mn_ammunition{playerid} = 30;
    }
    switch(mn_weaponid{playerid})
    {
        case WEAPON_COLT45: mn_price[playerid] = 1720;
        case WEAPON_SILENCED: mn_price[playerid] = 2135;
        case WEAPON_DEAGLE: mn_price[playerid] = 2476;
        case WEAPON_SHOTGUN: mn_price[playerid] = 1459;
        case WEAPON_SAWEDOFF: mn_price[playerid] = 1928;
        case WEAPON_SHOTGSPA: mn_price[playerid] = 2836;
        case WEAPON_UZI: mn_price[playerid] = 1838;
        case WEAPON_MP5: mn_price[playerid] = 2382;
        case WEAPON_AK47: mn_price[playerid] = 3718;
        case WEAPON_M4: mn_price[playerid] = 3967;
        case WEAPON_TEC9: mn_price[playerid] = 2593;
        case WEAPON_RIFLE: mn_price[playerid] = 4391;
        case WEAPON_SNIPER: mn_price[playerid] = 5628;
    }
    switch(mn_weaponid{playerid})
    {
        case 22, 23, 24: mn_slot{playerid} = 2;
        case 25, 26, 27: mn_slot{playerid} = 3;
        case 28, 29, 32: mn_slot{playerid} = 4;
        case 30, 31: mn_slot{playerid} = 5;
        case 33, 34: mn_slot{playerid} = 6;
    }
    return 1;
}  

или

static stock GetWeaponInfo(playerid)
{
    static 
        weaponid;
    static const
        slot[] =
        {
            2, 2, 2, 3, 3, 3, 4, 4, 5, 5, 4, 6, 6
        },
        ammunition[] = 
        {
            17, 17, 7, 1, 2, 7, 50, 30, 30, 50, 50, 1, 1
        },
        price[] =
        {
            1720,
            2135,
            2476, 
            1459,
            1928, 
            2836, 
            1838, 
            2382,
            3718, 
            3967, 
            2593, 
            4391,
            5628 
        };
    weaponid = mn_weaponid{playerid}-22;
    mn_slot{playerid} = slot[weaponid];
    mn_ammunition{playerid} = ammunition[weaponid];
    mn_price[playerid] = price[weaponid];
    return 1;
}