A short guide to the M14 Rifle as to whether or not the "Button" (selector lock) or "Switch" was used.

Back in the day, the selector lock was the "as issued" setup on all M14s that came from the manufacturer and those rifles that were changed into squad automatic rifles had the switches installed at the Armory. Switches were also installed on a company level to those designated as squad automatic weapon carriers. Usually 2 per 16 man squad with 3-4 squads per platoon.

In modern times where some of the rifles may be built by outside entities, the Switch could be installed befor the Military get's their hands on them.

Below is a list of some of the rifle setups under two categories; Button and Switch.

Button

Rack grade "Standard Issue" M14s
M21
M25
National Match M14s

Switch

Rack Grade with USGI or aftermarket version bipod
DMR M14s
EBR

Of course it's really up to the individual what their preference is. The above lists are more for those that would like their rifles in the "correct" configuration for their project.