The CMMG Mk4 Receiver Extension Buffer Tube Lock Nut is a replacement part for MSR receiver extensions. This AR castle nut is built to meet military specifications to provide long-lasting and reliable quality. This buffer tube lock nut is great for repairing or building a lower receiver extension. Repair your tactical rifle with the CMMG Mk4 Receiver Extension Buffer Tube Lock Nut.Features:
KG15 Glock Billet Rifle Lower Receiver- Complete
$322.95 
AR-556 Multi-Caliber Lower Receiver with Elite 542 Trigger - Black
$349.00 
MK4 Receiver Extension Buffer Tube Lock Nut
$9.99 
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