In addition to custom barrels for a plethora of bolt-action rifle models, Shilen Rifles, Inc. also offers drop-in barrels for the AR platform. Available in a variety of different chamberings, contours, lengths and finishes, Shilen currently produces nine SKUs for the AR-10 and 11 for the AR-15. Machined from a pre-threaded blank, each barrel is assigned a bolt assembly prior to fabrication and is then chambered to the correct headspace for that bolt. A stainless steel 24" Heavy Varmint test barrel, chambered in .204 Ruger with threads cut to 5/8x24 TPI at the muzzle, displayed superb accuracy on the range, posting consistent sub-m.o.a. five-shot groups. Price: $555. Contact: Shilen Rifles, Inc.; (972) 875-5318; shilen.com.