I'm reminded of Ian over at Forgotten Weapons which has presented several rifles which were converted from the old thing to the new thing, say bolt action to semiautomatic.

Each time the government looked at existing stock, thought "hmm surely we can save money by refurbishing these old firearms".

And just about each time they at best ended up with a subpar weapon that cost as much as a brand new model designed from scratch. And often something which cost way more...

The idea looks better on paper than it usually is.