Lets look at it this way. The M.E.C is a coalition formed shortly after this hear. Basically 2010ish we'll say for this sake. They have there army formed up and trained for 2012ish (Two years sounds ok I suppose.)
Now this all greatly depends on the economic status. Based on what little information I can gather through both general deduction and the current setup in the game we have come to this.
The RIFLE!
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Currently the G3 is owned as a 'quick arm' solution to the M.E.C, Be it something like a current off-loading a ton of stored weapons or simply being able to produce it decently well themselves. The rifle is a good rifle don't get me wrong and the ease of it makes it perfect for a newly-formed army. Looking at it in that way, you could assume M.E.C have the money but prefer more to have there units trained and ready with a common yet rugged robust and simple weapon.
Now lets consider that the M.E.C being very battle-hardened from 10,000 battles all oddly in like the same 10-20 places.. Virtual Battlefields are odd like that. Annnyway. Looking at it this way. They feel its time to upgrade there arsenal. They've done several tests and get a whole kit of G3s crated up and hauled off to there second line troops. During all this fighting, mostly with US and British forces they've captured thousands of pounds of ammo from supply routes, seen how the 5.56mm preformed and how deadly the US and British were with there rifles. Where do we go from there? The world is changing. They notice that even Russia has shifted from the 7.62mm and decide like all good modern natures to jump off the ol' bullet and snap up a new one.
So our M.E.C guys go sniffing about for a new rifle. They are on the brink of what seems like a constant war. They will basically only have time to drop these rifles in there soldiers hands and hope for the best. The G3 never wronged them and they go over to there buddies in H&K. A taped conversation to follow.
MEC guy: Hey uh.. We need a new rifle... Some people are complaining that we aren't nifty. Its gotta have sight rails and stuff... And um... Its gotta look fancy.
H&K guy: Wait huh? Ah.. Lemme uh.. Look into it..
*H&K guy digs into a handy cabinet marked 'failed projects, try to sell them.' The H&K guy passes it across.*
MEC guy: This looks like our old rifle.
H&K guy: Ya exactly! Its easier for your guys.....
*The rest of this tape is boring and we'll stop now.*
So the weapon the MEC guy takes back along with a ****-ton of machines to build them is the H&K G41. It never really found any customers but the high-cost and quality of the weapon doesn't really bother the MEC all that much. Firing the new 5.56mm NATO they get a nice package deal and to ease the transition into the new rifle the full auto ammo waster from the G3 was removed and the G41 is fitted with the same 3 round burst as the US rifles.
Modern Firearms - Assault Rifles - HK G41
HKPRO: The G41 Automatic Rifle
**** we need a new LMG... Wait a second SVD!? We need to upgrade that bad.....
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So MEC realizes the ammo change had a bigger effect then it thought it would. They realize that they are gonna have to shift a lot of there equipment to make this work right and proper-like. So they get to work researching it.
First thing they notice is quite simple, Why are we using this SVD?! This dated old rifle when we could go back to our lovely G-3 line and pick up a nice MSG-90 hmmm? That sounds better ya someone write this down so we can send our order to them!!!
Modern Firearms - Heckler-Koch HK MSG-90 sniper rifle
So we got that sorted out. Hrm. Oh yes those big shootie loud guns. That machine gun. Lets see here... Don't we already own this one? Oh HK23E. My fault I'm not that good with numbers. So it uses the same bullet you say? Alright sounds good to me place the order.
Modern Firearms - HK 11, HK 21, HK 13, HK 23 machine gun
Hey this just solved our spec-ops rifle problem. We are all shooting the right ammo now. Well lets stay with this. What else do we need? What our crewmen are complaining? What does this fellow want? "Expendable Grunt", "Bob Marley" Who the hell? What do they want.
Modern Firearms - FN P90 personal defense weapon / submachine gun
Tell them we'll think about it.
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Yes I am aware thats EXTREMELY long so lets get a summary
Rifle: H&K G41
LMG: HK23E
DMR: MSG-90
Crewman kit: P90. (That one is a tad well jokish.)
I am aware I put way to much effort into that but I was in a writing mood.
It still does not make sense to use NATO and non-NATO calibres, especially for standard kits like the support gunner.
