if you already have a bearing spring guide get rid of the bearing piston head. Its pointless and it will reduce the weight slamming into to your MB. Swiss cheese your piston to further reduce weight or start modding your piston head or/and cylinder head. Understand, these mods will reduce MB ware but there will be a FPS drop. You could use a SystemA silent head or bore up kit to pad your cylinder/piston head or an Angle head which use a form of an air brake if you don't want to do the mods. Air brakes are the most effective and they tend to quite your gun done too.
You can make an air brake
http://64.233.179.104/translate_c?hl...3DgJ0%26sa%3DG
or a padded cylinder head
http://64.233.179.104/translate_c?hl...3DgJ0%26sa%3DG
http://64.233.179.104/translate_c?hl...3DgJ0%26sa%3DG
you could also stretch for a CNCed MB.