Due to the number of manufacturers making components for ARs and the variance of tolerances & quality between those manufacturers some parts combinations will require more fitting work than others. The higher quality parts will usually require less fitting. And the labor price will be on the lower end of the scale

Price is for removing factory Mil-Spec sight gas block and installing a low profile one. 

Price is for installation on pre-threaded barrel.

Price depends on complexity of rail system to be installed. Amount of time it takes to disassemble old system and install new one. If old parts have had permanent thread locker used on them etc. The labor charge will be higher. Price is commensurate with amount of labor involved.

Components are tuned for a smoother and more efficient extraction/ejection cycle.

This service is for shrouded carriers and mil spec rounded hammers.

Bolt group is polished to give smoother movement and less drag between moving parts. The extractor and ejector are tuned, hammer face polished, chamfer firing pin hole. This cannot be completed on bolt carriers with plated finishes like hard chrome or Nickel Boron.

Inspect gas tube for gas flow, blockage or damage. Alignment of gas block and barrel port. Inspect gas rings, detail strip bolt and clean. Gas system is cleaned from barrel to bolt carrier.

Detail strip and clean. Inspection and mechanical check of all parts for proper function. Check for excessive wear. Damage from improperly fit parts.

Improves performance by allowing more gas to flow through the system. For guns that are having cycling problems due to inefficient gas volume.

Factory components are tuned to create a smooth and crisp 4.5lb trigger pull.

Price includes parts. 

Detail strip and clean.