The Mak is every bit the pistol that that the 'Beretta 70 Series' is if not more so. The Mak is certainly more reliable, tougher, and the 9x18mm cartridge is more potent than the .380.
As for your M21 with the tiny, itsy bitsy, utter POS worthless .22LR barrel that MIGHT stop a charging chipmunk.
You're dead wrong on the accuracy. The Mak has a fixed barrel and is one of the most accurate production centerfire pistols you can get.
As for threading the barrel, you can get barrels for the Mak, blued or stainless, in either 9x18mm or .380, that are 1/2" longer and already threaded, with one of several threading options. The one I have will thread an M-16 flash suppressor onto it if that tells you anything.
Changing the barrel by yourself on a Mak requires a hand held Mak barrel press, which can be had for pretty cheap. You also will need to drill a 3mm hole in the block of metal that protrudes from the lower side of the barrel's breach to custom fit that barrel into the pistol and hold the barrel retainment pin.
THAT is about 1/100th the work of super-modifying your POS M21 for a homemade extractor and a fixed barrel, and the Mak will still hit far, far harder.
The Mak safety comes out in about 1 second. You can get a spare safety and modify it so that the hammer drop doesn't work, but it will still lock the slide so you can fire it suppressed with no slide noise. This is what the Russian military does with Maks that their special forces use.
The Mak is a silencer nut's dream pistol. Too bad you insist on being so ignorant and hard headed about it.