X M 1 7 7 E 2
had problems with accuracy and barrel durability, due
the use of tracer rounds. Colt's proposed exploratory
program, but finally US DoD did not give permission to
grant amount of money expected by Colt.
Limiting US Armed Forces involvement in Vietnam War,
was the main reason why manufacturing of CAR-15
Commando rifles was 1970 abandoned. The direct suc-
cessor of Commando was Colt Model 653 versions of
M16A1 with 14.5" barrel with extended reliability.
Troy XM177E2
As every AR-15, Troy XM177E2 fires from closed bolt.
It actions by diverting combustion gases by tiny hole
in the barrel with system named Direct Gas Impinge-
ment (DI, known mostly as Stoner system). On the up-
per part of bolt carrier is gas key that front part is in
contact with thin steel tube placed directly over the
barrel that guide, supply and direct combustion gases
when bolt carrier group is in forward position. When
BCG is placed in rear position front of Gas key is be-
hind the gas pipe. Gas key directs combustion gases to
gas chamber that is placed between back part of the
bolt and bolt carrier. There were placed three gas rings
on the bolt that are designed to block gases to come
out from gas chamber. Bolt with seven wings is locked
by rotation. Troy XM177E2 was made in 100% with
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