attachBitmap and zooming - image quality help

Hi there,
I’m using BitmapData to duplicate a mc.

import flash.display.*;
function duplicateMC(mc:MovieClip, mc2:MovieClip) {
var mcBMP:BitmapData = new BitmapData(mc._width, mc._height, true, 0x00FFFFFFFF);
mcBMP.draw(mc);
mc2.attachBitmap(mcBMP, this.getNextHighestDepth());
}

duplicateMC(mc_container.mc_loader, mc_container.mc_loader_bitmap);

The movie clip I am duplicating loads in another movie clip swf.
This works well, but the bitmap duplication of the movie clip is jaggered and pixelated - this also needs to zoom in.
I am using Actionscipt 2.
Having searched around, I am aware of:

forcedSmoothing
and
mc._quality = “BEST”
Neither of these seems to be the answer - any advice would be much appreciated.

Best
Fin