Husqvarna line up. 310 series is the best. Made 1912 to about 1949. Guns after serial number 165,000 will have 2 3/4" chambers. All have greener cross bolting. Letter suffix to the 310 speak to barrel steel type and engraving if any. 610 series built 1949 to 1952. Lacks Greener cross bolt lock up. Generally not as well designed or built as the 310 series. The 615 series was made 1949 to 1952 very few built (around 2000) same basics as the 610 guns. 350 series were built 1952 to 1960 most but not all had greener cross bolts. Further decline in manufacture quality as previous guns. 1310 series. Built 1959 to 1970. Build quality was restored and this series of guns were well received during manufacture. Too little too late and no further production occurred after 1970. Most had greener cross bolting. If I had to choose a Husqvarna built gun it would be a 2 3/4" chambered 310 or a 1310 series shotgun.
Darryl