I got a CZ452 Americanin LH this summer. It has shot groups as small as 3/8" at 50 yards with Wolf MTto a little over 1/2". Some ammo goes around 1/2" while others go 3/4 to 1".
Had a Marlin 39M about 40 years ago and doubt it would hold a candle to this one. Mines has Brooks trigger in it. Figure on spending some money to a get a 39 trigger as good.