Originally Posted by
Skyyr
Not true. At ~1,000,000 trigger pulls before wearing out (probably a low estimate), it'd be easier to simply replace a lower receiver for $100-200 than it is to absorb the extra $5, $10, $20 - whatever it is - cost per every carbine the military buys. Most of them don't see that many rounds in their lifetime and would not be close to wearing out, so it's a saved cost.
The military does not always do things the best way, they simply attempt to do them the way that's most effective with how they currently operate.