[HamletEagle]

Well...yes.

remove_entity and remove_entity_name are the same thing, the last one is a stock which call remove_entity on the specified classname(it loops all ents that have the given identifier). Since remove means actually remove, using such functions on armoury_entities will make them unable to spawn on new round.
Metalicross way sets the item count to 0, so it will contain 0 weapons of it's type and make them invisible, this is the trick.

Now, why removing them make them unable to respawn ?

When the item count from an armoury is decremented to 0 the armoury will get hidden and on new round the m_iCount is restored, so the actual ent is not removed when m_iCount is 0.

Look at this decompiled code by Arkshine:

PHP Code:

void CArmoury::ArmouryTouch( CBaseEntity *pOther )
{
    if( pOther->IsPlayer() && !pOther->m_fIsVIP )
    {
        if( m_iCount > 0 )
        {
            if( m_iItem <= 13 )
            {
                if( pOther->m_fHasPrimaryWeapon )
                {
                    return;
                }
                
                m_iCount--;

                switch ( m_iItem )
                {
                  case 0 :
                    pOther->GiveNamedItem( "weapon_mp5navy" );
                    pOther->GiveAmmo( 60, "9mm", 120 );
                    break;
                  case 1 :
                    pOther->GiveNamedItem( "weapon_tmp" );
                    pOther->GiveAmmo( 60, "9mm", 120 );
                    break;
                  case 2 :
                    pOther->GiveNamedItem( "weapon_p90" );
                    pOther->GiveAmmo( 50, "57mm", 100 );
                    break;
                  case 3 :
                    pOther->GiveNamedItem( "weapon_mac10" );
                    pOther->GiveAmmo( 60, "45acp", 100 );
                    break;
                  case 4 :
                    pOther->GiveNamedItem( "weapon_ak47" );
                    pOther->GiveAmmo( 60, "762Nato", 90 );
                    break;
                  case 5 :
                    pOther->GiveNamedItem( "weapon_sg552" );
                    pOther->GiveAmmo( 60, "556Nato", 90 );
                    break;
                  case 6 :
                    pOther->GiveNamedItem( "weapon_m4a1" );
                    pOther->GiveAmmo( 60, "556Nato", 90 );
                    break;
                  case 7 :
                    pOther->GiveNamedItem( "weapon_aug" );
                    pOther->GiveAmmo( 60, "556Nato", 90 );
                    break;
                  case 8 :
                    pOther->GiveNamedItem( "weapon_scout" );
                    pOther->GiveAmmo( 30, "762Nato", 90 );
                    break;
                  case 9 :
                    pOther->GiveNamedItem( "weapon_g3sg1" );
                    pOther->GiveAmmo( 30, "762Nato", 90 );
                    break;
                  case 10 :
                    pOther->GiveNamedItem( "weapon_awp" );
                    pOther->GiveAmmo( 20, "338Magnum", 30 );
                    break;
                  case 11 :
                    pOther->GiveNamedItem( "weapon_m3" );
                    pOther->GiveAmmo( 24, "buckshot", 32 );
                    break;
                  case 12 :
                    pOther->GiveNamedItem( "weapon_xm1014" );
                    pOther->GiveAmmo( 24, "buckshot", 32 );
                    break;
                  case 13 :
                    pOther->GiveNamedItem( "weapon_m249" );
                    pOther->GiveAmmo( 60, "556NatoBox", 200 );
                    break;
                  default:
                    break;
                }
            }
            else
            {
                switch ( m_iItem )
                {
                  case 14 :
                    if( pOther->AmmoInventory( pOther->GetAmmoIndex( "Flashbang" ) ) >= 2 )
                        return;
                    pOther->GiveNamedItem( "weapon_flashbang" );
                    break;
                  case 15 :
                    if( pOther->AmmoInventory( pOther->GetAmmoIndex( "HEGrenade" ) ) >= 1 )
                        return;
                    pOther->GiveNamedItem( "weapon_hegrenade" );
                    break;
                  case 16 :
                    if( m_iKevlar == 1 )
                        return;
                    pOther->GiveNamedItem( "item_kevlar" );
                    break;
                  case 17 :
                    if( m_iKevlar == 2 )
                        return;
                    pOther->GiveNamedItem( "item_assaultsuit" );
                    break;
                  case 18 :
                    if( pOther->AmmoInventory( pOther->GetAmmoIndex( "SmokeGrenade" ) ) >= 1 )
                        return;
                    pOther->GiveNamedItem( "weapon_smokegrenade" );
                    break;
                  default:
                    break;
                }
                
                m_iCount--;
            }
        }
        
        if( !m_iCount )
        {
             pev->effects |= EF_NODRAW;
        }
    }
} 


PHP Code:

if( !m_iCount )
{
             pev->effects |= EF_NODRAW;
} 


The snippet shows that when the item count is 0 the armoury is set to invisible.