Used Rainier Arms Switch 13" Handguard Mlok: https://www.rainierarms.com/rainier-arms-m-lok-switch-5-56-rail/
$180 160 140
New Rainier Arms Forged upper Receiver Assembly: https://www.rainierarms.com/rainier-arms-forged-a4-upper-receiver-gen2/
$100 SOLD
Used Seekins Precision 14.5" 223 Wylde...