If the Model 100 I looked at on GB is the same one, either the stock is a replacement or the original has been rasped down & recheckered, as the checkering pattern is not the standard Winchester pre-64 pattern used on those rifles.
The front swivel, used to take down the rifle by removing, IIRC, has been converted from a standard to a QD or replaced by a QD, along with the rear.
Winchester contracted a gunshop in upper New York State to handle the firing pin upgrades, during the recall.
Here's the Winchester blurb:
The model 100 recall was issued as notice 7-1990 by Winchester.
In short, it advised that the firing pin may break due to use and metal fatigue and become lodged in the breech bolt face. If this occurs, the firearm may fire before the action is locked causing damage to the firearm and injury to the shooter and/or bystanders.
A new firing pin was designed to replace the original pin. Winchester advised against use of the firearm until a replacement pin could be installed. Winchester advised to send the gun to a authorized service center for the pin replacement.
You can obtain additional info from Winchester at 1-800-852-5734. This is a dedicated line/number for owners of the Winchester 100 concerning the firing pin recall.
The old firing pin was lathe turned - round. The new style is similar on the front and back but in the front midsection it has two flats milled, one on each side making the center section much stronger.
Upon completion of the recall/repair, the shop doing the work was to have test fired the gun and to then stamp an assigned letter on the inside top of the receiver as seen through the magazine well with the bolt retracted.
These letters were assigned to various repair centers and although not important as the shop ID, it is important in helping you determine if the repair was made. The letters that were stamped inside on the top inside of the receiver were: "B", "L", "N", or "X".
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