Post by Mark Looking at the "problem" now, it appears to me that the suppressor that you have linked to might not fit if it depends on the length of barrel that extends beyond the front sight tower assy as the XM's barrel is shorter than the M4 in this area. The fact that this suppressor is designed to fit an M4 should not be over looked.
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Wanted to buy: MGC Sten MK3....trades?(still)
MGC MP40 Marushin MP40 Nakata MP40 TRC MP40
Modelgun manufacturers, past and present:CMC,CAW,Hudson,HWS,LS,MGC(R.I.P. 1960's~2007) Marushin,Marui,Kokusai,Shoei,Tanaka and Western Arms