Marlin Model 99's and their variants like the Glenfield Model 60, and all those other Model variations made for the BigBoxStores made before the GunControl Act 1968 went into effect,,,were not ser#'d.
When Marlin started ser#'g them, the # was stamped on the LH side of the recv'r at the front upper edge.
There are a very few around that were made prior to the GCA68 that came back to the Marlin Factory as warantee returns. These rifles had no ser# factory stamped on them as they were pre-68 mfg'r.
Up to the very eary 70's, Marlin would take those Warantee Returns and simply refinish and re-build them. Repackage and resell as a new rifle.
IF the rifle in question was one of the pre-68's that came thru w/o a ser#, we in the Service Dept would hand stamp a new ser# onto the recv'r in the correct location. The new # was off of a running list provided by the management and as each one was used, it was deleted from the list.
The hand stamped number is easily seen on the frame as being so. No jig or fixture was used to line up the hand stamps. Some 'smiths took better care in doing the job than others of course.
The 'refinish' to the alloy frame of the rifle was a scrub down and a rattle can spray semi gloss or flat black laq or enamel recoating. Same with the alloy trigger guard.
How's that for Marlin Quality of the late 60's and early 70's..
The whole idea was scrapped by '72 or so as too time consuming. The stripping for parts was done for a time.
The final solution for these returns was to simply destroy them by cutting them into 1/3'ds
.22 semi autos and the 22 bolt rifles as well (80's and 81's and their House Brands as well).
FWIW -When Marlin discontinued the Glenfield line,,they took the Model 60 designation that had been used for the Glenfield Model 60 version of the Marlin 99 and assigned that to the Marlin 99.
Making their Marlin semiauto rifle the Model 60,,and retiring the Model 99 designation.
Truth is that the rifle as the Model 60 (Glenfield and the other Glenfield variations) out sold the Model 99 Marlin by a big margin. The Marlin marketing geeks thought the Model 60 designation had a wider appeal and better name recognition if that's the right way to put it.
