The early 90's had the forend held on with a simple over-center spring (J Spring).
The earliest of those have the forend iron NOT extending to the action/frame flat when viewed from the side.
Then the iron was redesigned and it was extended so it was level with and made an unbroken line with the side of the frame.
Both these used the J-Spring attachment. The latter was used to the early 50's.
Then the finger operated pull down latch was used to lock the forend onto the bbls after that and till the end of production,about 1962/63.
Side ribs on the bbls until about the same time as the switchover to the manual forend latch,,early 1950's.
No ribs from there on out on regular production,just the separating block at the muzzle.
Double trigger guns were discontinued about '57. But remaining inventory got sold sometimes a few years later. The Single trigger came about a couple years prior to the twin trigger model being dropped.
The 'SkeetKing' Model is one of the rare ones that accumulators look for. 12,16,20 & 410. better grade wood, engraving, ect. Supposedly bbls adjusted for best Skeet patterning. It's a pre-War offering only IIRC, just a couple years.
The Combination rifle/shotgun M90's getsome attention too. These were also pre-War guns. Even a few O/U rifles made in small calibers.
Smaller dia strikers and steel firing pin bushings in the frame on factory made rifle caliber guns.
The frame is iron on these,,plenty strong for the gauges and small rifle cartridges it was made in.
It will turn a brown/red/purple color if reblued w/a hot salt bluing however and you see a lot of them that have been aftermarket reblued.
Rustblue was the original finish from the looks of them. The bbls definetly rust blued as they are soft soldered together
IIRC, the stocks were checkered on regular production guns starting just after WW2.
The pre-War guns were uncheckered,plain and marked either Marlin or Ranger.
Ranger marked guns were for sales through Sears who actually pitched the idea of the O/U to Marlin in the first place and kicked in a considerable amt to start the project.
Post-WW2 guns for Sears were to be marked JC Higgins.
No 'Marlin' marked guns were supposed to be sold through Sears, just their proprietary brand,,this was Sear's idea. But after WW2, Sears wanted and got Marlin to mark their guns with the Marlin name also.
Striker fired as mentioned,,the entire sear, striker, mainsprings, sear springs assembly is removed and installed as a unit. I think they called it a searbox that held all the parts together.
Makes for handy work, but you must compress the strikers w/a clamp before taking the unit out or putting it back in.
Don't try it w/o doing that! There's nice square opposing edges to clamp and compress everything but when working with springs, eye safety is a must. They can get away on you.
Check the safety for proper operation. Some can be fired with the gun on Safe. Some you can get the safety to move from Safe to Fire by repeatedly pulling the trigger,,kind of tapping on it with your trigger finger.
You won't know if the double trigger gun 'doubles' due to a worn sear or striker sear edge till you shoot it. Sometimes bouncing the UNLOADED but cocked gun on it's butt w/the safety off will display a worn sear by having it fire. Careful not to break the original butt plate if it's still on there.
You can check for yet side step the unpleasent doubling effect in live fire by placing a live round in one chamber and an empty in the other (I don't like to dry fire guns).
Fire the one live round and simply see if the second bbl is still cocked and will 'fire' the empty,,or if it has doubled and fired along with the first bbl.
The Single Trigger is a mechanical one and works off the guns recoil. A counter weight is supposed to block it from doubling, but that can fail too. Single triggers can just be a real problem no matter the brand.
When I worked at Marlin, they told customers that we didn't have any more parts to repair these after about 1971 and simply returned the guns to their owner.
In fact we had shipping crates full of them including bbl sets in any gauge and even rifle and combination bbl sets. All had been packed up at the NewHaven plant and taken to and stored in the new (at that time) North Haven factory. That got to be the line given to customers about most any of the older guns,,No Parts Available.
Last I knew the parts were all sold to Numrich,,and that was in the late 80's or perhaps early 90's.
