AS I have mention before, we really did not battle test the Ultimax 100 magazine system.. most drum mag system do not work very well when it gets dirty and prolong operations in the field... we are getting major complaints on the Beta C mags in Iraq and Afganistan... the russian and Chinese both abolish the drum system for the RPK , the Russian started with the drum for their RPK-74 and gave up and went back to a 45 rd mags!>
I ahve use both the U100 and the M249 and I like the U100 a lot in all ways except the feeding system.. all my SPecial forces and military freinds all commented the same thing I said, great system but poor feeding mechnisim on the Ultimax 100.
Improvement I feel they need,
1) Feeding system needs to be reevaluated
2) Barrel needs to be 1:9 twist for SS`109 and M193
3) picatinny rails for mounting of other aiming devices
4) M16 type mags interchangable ( I think this one has been address on the Mk 4)
5) Rate of fire can be increase!
DaveC