i found marlin screws to be pretty soft also. some screws are nearly stripped from repeated disassembly and one of the longer screws that goes through the barrel band snapped during recoil from firing. replacement parts for lever guns are expensive too
marlin also has quite a bit of tool marks on the inside. seems like they try to smooth out the more important contact points a bit though.
i like them for the price after a mild tuning. seems to be in between a winchester and a rossi in price and quality.
When remington bought marlin they screwed them up bad, which is why now the JM marked Marlins command a premium. The newer ones that ive seen, this year and the tail end of last are much better, but the ones prior are bad, sharp internals. bad screws, ive seen and heard of some that came New in Box with the screws broke, feeding issues, bad headspace, the list goes on. I recommend tuning for all cowbow action guns even if not being used as such, Marlins, Ubertis, Winchesters, they all benefit from it, and run alot more user friendly.