Removing the **sole** quality that makes it suitable for military use is not a "minor tweak"
Apparently you werent listening (or choose not to). The M-16 was designed to have low power/momentum specifically so on automatic fire a person can use it without falling on their ass or having their aim wildly thrown off by the recoil.
One you remove the automatic fire capability it has no relevance or use as a military weapon of anykind.
This is not a "minor tweak" it completely changes the utility of the weapon.