SOPMOD is still in reality an M4 carbine with a flat top, Full
auto lower, in M4 profile 1:7 twist barrel. with the Knights
industries RAS2 rails, forward grip, PAC4 laser and maybe a M68
Aimpint M2 scope or the ACOG TA-01NSN ..
THe basic problem of the M16 still exsisits which is fundamentally
flawed.
Gas being blow back into the bolt carrier and creating that
crystalized carbon in your bolt. We do 5 days training in Gunsite
AZ that goes thru 4000 rds in that duration both semi and Full auto
! We see a lot of jams ( IA drills) in the AZ desert. with proper
cleaning technique and maintainance this can be reduce but not
eliminated. I have personally seen SIG 550 series and Valemet , AK
and FNC weapons that does the same drills with no jam !
Not putting down the M16 system ( I do love them and own a few of
them ) but it has an inherit flaw in the system.
Also, the magazine system of the M16 is another problem! You do not
know "positively" if the mag is inserted properly espeically it is
fully loaded. even the you tap it when you insert the mag...Also!
if fullu loaded mags !sometimes after prolong use, the spring
tension and the shitty follower ( we had to change to a newer type
follower, I hope SAF look into that! ) . Well! the new Heckler and
Kock design M16 magazine helps in curing some of the problem! but
it is the weak link of the M16.!
Yes! the US ARMY, spec ops love the system, like any other system,
if you train the user properly, and they know how to handle it !
the system will work good. However, if there is a better system and
an improvement over it will help ease the inherit problem, than it
may be a good idea to look into it.
IN fact Heckler and Koch recenlt release the HK M16 conversion that
incorporate a piston ( like the AK, Steyr, SIG) system.....
Hopfully this will be marketed soon! call the HK M416! 
can;t wait to get my hands on them!
http://www.hkdefense.us/pages/military-le/rifles-carbines/hk416.html
DaveC!
