Bolster Armouries MPX sig sauer Obire

Bolster Armouries MPX sig sauer Obire Had this since release. Recently had an issue with the piston stripping and the pinion gear. This has been fixed and gears have been replaced with gate 13:1 gears set and an airtech nightsalker piston. Its fires perfectly fine. Fully upgraded and rapidly fast! Comes with 8 mpx sig mags and a tap airsoft m4 adapter. Open to trade for HPA or TM NGRS Collection shrewsbury. Postage at buyers cost. £450 ono