I am most upset over the procurement of the M16 rifles. Just read “The Gun” by Chivers
http://www.amazon.com/Gun-C-J-Chivers/dp/0743270762. It is disgusting to read how the Military Industrial Complex puts profits above everything. It was so repellent reading the history of the M16 procurement that I felt like throwing the book across the room . It is a tale of greed: the lives of good American Soldiers are tradable in the Corporate quest for obscene profits. Beneficiaries are the Military sock puppets who receive promotions and post employment opportunities and the Congressmen who receive Corporate contributions creamed from Defense contracts.
This situation is the same now as it was then.
(How many Marines have to die to get an Osprey to fly?)
However after hundreds of millions of additional tax payer funds, Colt was able to tinker around the edges and make the M16 a mechanically reliable platform, but was never able to fix the fundamental flaws of the M16.
I consider DI one of the fundamental flaws of the M16.
The "poops where it eats" comment is one of those negatively meant accusations thats actually true - but the deliberate lie is that the M16 is unique in that. Nope, had a HK91, and that gun rates twice as dirty, the delayed roller lock action is really inertia blowback, and it gets nasty. So do all my auto pistols and the 10/22. They ALL poop where they eat. So does the M60, M249, M17, M2, and a few others I've cleaned.
AK's do it too. Dirty brass, dirty bolt. The guy who started that expression was actually right, it's the AR haters showing their ignorance about guns that's actually funny.
All semi auto mechanisms unlock when there is residual breech pressure, this is to lengthen the amount of time energy is available to function the mechanism. This causes some fouling to be blown into the mechanism.
However, direct impingement mechanisms add, and add considerable to the fouling, by venting directly into the mechanism. DI’s are always going to more dirty.
Comparison of fouling levels was interesting to me:
http://www.ar15.com/forums/t_3_126/...SR_35___gas_system_retrofit_range_report.html
AR's will always be more maintenance heavy than non DI actions, but given careful and constant cleaning, a well built AR is a mechanically reliable firearm.
As for HK91’s, 308 rifles have about twice the powder charge of a .223 so you would expect more fouling. The roller bolt is a very successful action, there are a few countries that are actually manufacturing variants of HK91’s and issuing them to their militaries. Pakistan is one, just look at what they carry. They make them locally. I have seen Mexican troops with HK91’s but I don’t know where they got them. What weapons Armies buy with their own nickel is quite revealing. Yes, there are a lot more users of the M16 platform with its DI, but those are countries that are getting their M16’s free from the American tax payer.
Not counting Mexican Drugs lords who get their AR's direct from the BATF.