Hi folks,

I was looking on Trijicon's website at the TA01NSN tonight (here), and it states
the following:

"The TA01NSN was designed specifically for the US Special Operations
Command SOPMOD M4 Carbine.  To meet their requirements, the reticle
bullet drop compensator and range finding stadia lines are based on
the trajectory of the 62 grain bullet from a 16 inch barrel,
flattop mount (Picatinny rail Mil.Std.1913)."

I thought the SOPMOD M4 Carbine had a 14.5" barrel - am I missing something ?

I plan on getting one of these ACOGS, but I am trying to decide on whether
or not to go with a 14.5" barrel (with permanent Phantom), or a 16" barrel.

The Trijicon web page for the TA31RCO also states the following:

"The TA31RCO is an Advanced Combat Optical Gunsight (ACOG) designed
for the M16M4 weapon system (16" barrel)" - with regards to their
scoped designed for the "USMC Rifle Combat Optic (RCO) for M4 (16)".

Does this mean that the USMC is using a 16" M4 variant, and that the Trijicon
listing for the TA01NSN for that Army's M4 SOPMOD may mistakenly say 16" when
it means 14.5" ? Are they both wrong ?

Any thoughts ?

A lot of people can answer your question better then me as to the barrel length of the M4 I also thought
it was 14.5.  Having said that a 16 inch barrel would not make enough difference to make the reticle inaffective.

Give some consideration to the Leupold Tactical 1.5x5 MRT/M2 and IOR both good scopes.