I never liked the C79, too unreliable. the new A2's are better but I dislike it for the following reasons
- issues with holding zero, when you put pressure on the top of the sight it moved your zero point. Due primarily to the crap mount, this may not seem like an issue for many, try shooting prone with a helmet on.
- complete lack of back up sights. There are some poopy battle sights on top of the rubber armour of the sight but they are easily broken off and are not reliable. BUIS are an absolute requirement, especially in the current operational environment where IED's remain the largest threat. Having a sight fragged is a very real possibility to which the CF has not developed an answer.
- the c79 causes serious tunnel vision in troops. A variable power optic (1-4X) would be far superior, if I remember correctly the C79 is 3.4X. A surprisingly high percentage of the Canadian Forces have never fired with iron sights. Or any other sight for that matter, having a zero magnification sight or a variable magnification sight would be far preferable to a fixed magnification sight.
- the Tritium that everyone is a fan of degrades over time to the point where it doesn't glow whatsoever. something that is a problem in low light situations,
- Eye relief can be extremely finnicky in the C79. it can be very frustrating to get the sight in the perfect location
I've shot an m4 and m16 with an ACOG overseas and it is a significantly more robust sight. it has some similar issues with tunnel vision and such. it has some pretty serious built in BUIS, but using them required me to break cheek weld to fire them, not ideal but workable. On a side note the 2 designated marksmen in our platoon were issued with Schmidt and Bender variable power scopes that worked like a charm.