CS Style USP : Client Side tutorial - Half Life Modding Kit for Half-Life

In the Client Workspace open the ev_hldm.cpp and paste this under ( not inside ) the EV_FireGlock2 function:

//======================
//	    USP START
//======================
enum usp_e {
	USP_IDLE1 = 0,
	USP_SHOOT1,
	USP_SHOOT2,
	USP_SHOOT3,
	USP_SHOOT_EMPTY,
	USP_RELOAD,
	USP_DRAW,
	USP_ADD_SILENCER,
	USP_IDLE1_U,
	USP_SHOOT1_U,
	USP_SHOOT2_U,
	USP_SHOOT3_U,
	USP_SHOOT_EMPTY_U,
	USP_RELOAD_U,
	USP_DRAW_U,
	USP_DETACH_SILENCER
};

void EV_FireUsp1( event_args_t *args )
{
	int idx;
	vec3_t origin;
	vec3_t angles;
	vec3_t velocity;
	int empty;

	vec3_t ShellVelocity;
	vec3_t ShellOrigin;
	int shell;
	vec3_t vecSrc, vecAiming;
	vec3_t up, right, forward;
	
	idx = args->entindex;
	VectorCopy( args->origin, origin );
	VectorCopy( args->angles, angles );
	VectorCopy( args->velocity, velocity );

	empty = args->bparam1;
	AngleVectors( angles, forward, right, up );

	shell = gEngfuncs.pEventAPI->EV_FindModelIndex ("models/shell.mdl");// brass shell

	if ( EV_IsLocal( idx ) )
	{
		EV_MuzzleFlash();
		gEngfuncs.pEventAPI->EV_WeaponAnimation( empty ? USP_SHOOT_EMPTY : gEngfuncs.pfnRandomLong ( USP_SHOOT1 , USP_SHOOT2 );

		V_PunchAxis( 0, -2.0 );
	}

	EV_GetDefaultShellInfo( args, origin, velocity, ShellVelocity, ShellOrigin, forward, right, up, 20, -12, 4 );

	EV_EjectBrass ( ShellOrigin, ShellVelocity, angles[ YAW ], shell, TE_BOUNCE_SHELL ); 

	switch ( gEngfuncs.pfnRandomLong ( 0, 1 ))
	{
	case 0:
		gEngfuncs.pEventAPI->EV_PlaySound( idx, origin, CHAN_WEAPON, "weapons/usp1.wav", gEngfuncs.pfnRandomFloat(0.92, 1.0), ATTN_NORM, 0, 98 + gEngfuncs.pfnRandomLong( 0, 3 ) );
		break;
	case 1:
		gEngfuncs.pEventAPI->EV_PlaySound( idx, origin, CHAN_WEAPON, "weapons/usp2.wav", gEngfuncs.pfnRandomFloat(0.92, 1.0), ATTN_NORM, 0, 98 + gEngfuncs.pfnRandomLong( 0, 3 ) );
		break;
	}
	EV_GetGunPosition( args, vecSrc, origin );
	
	VectorCopy( forward, vecAiming );

	EV_HLDM_FireBullets( idx, forward, right, up, 1, vecSrc, vecAiming, 8192, BULLET_PLAYER_9MM, 0, 0, args->fparam1, args->fparam2, 0, 0.1, 0 );
}

void EV_FireUsp2( event_args_t *args )
{
	int idx;
	vec3_t origin;
	vec3_t angles;
	vec3_t velocity;
	int empty;

	vec3_t ShellVelocity;
	vec3_t ShellOrigin;
	int shell;
	vec3_t vecSrc, vecAiming;
	vec3_t up, right, forward;
	
	idx = args->entindex;
	VectorCopy( args->origin, origin );
	VectorCopy( args->angles, angles );
	VectorCopy( args->velocity, velocity );

	empty = args->bparam1;
	AngleVectors( angles, forward, right, up );

	shell = gEngfuncs.pEventAPI->EV_FindModelIndex ("models/shell.mdl");// brass shell

	if ( EV_IsLocal( idx ) )
	{
		EV_MuzzleFlash();
		gEngfuncs.pEventAPI->EV_WeaponAnimation( empty ? USP_SHOOT_EMPTY_U : gEngfuncs.pfnRandomLong ( USP_SHOOT1_U , USP_SHOOT2_U );

		V_PunchAxis( 0, -2.0 );
	}

	EV_GetDefaultShellInfo( args, origin, velocity, ShellVelocity, ShellOrigin, forward, right, up, 20, -12, 4 );

	EV_EjectBrass ( ShellOrigin, ShellVelocity, angles[ YAW ], shell, TE_BOUNCE_SHELL ); 


		gEngfuncs.pEventAPI->EV_PlaySound( idx, origin, CHAN_WEAPON, "weapons/usp_unsil-1.wav", gEngfuncs.pfnRandomFloat(0.92, 1.0), ATTN_NORM, 0, 98 + gEngfuncs.pfnRandomLong( 0, 3 ) );


	EV_GetGunPosition( args, vecSrc, origin );
	
	VectorCopy( forward, vecAiming );

	EV_HLDM_FireBullets( idx, forward, right, up, 1, vecSrc, vecAiming, 8192, BULLET_PLAYER_9MM, 0, 0, args->fparam1, args->fparam2, 0, 0.1, 0 );
}
//======================
//	   USP END
//======================

The other stuff that i missed out can be completed by yourself.