Marlin 336 scope mounting problem


April 23, 2007, 07:44 PM
All - I have a relatively old Marlin 336, so it's past a warranty return for the problem at hand. I went to mount a weaver scope base and found that the mounting screws protrude far enough into the receiver that they impact the bolt, not letting me cycle the action.

My solution was to mount a very hard piece of rubber under the scope base just thick enough to remedy the problem. I did take the scope base back and exchange it for another, with exactly the same problem. Any others have a similar problem?

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April 23, 2007, 07:55 PM
I have a 336 made in 1964, and the Weaver brand base mounted just fine.

April 23, 2007, 08:15 PM
The only thing I can figure is that the top of the receiver was machined a little too thin. Just to be clear, this 336 is stamped Model 3000 and was probably made for a retail chain. Not that it should have anything to do with quality control, but you never know.

I should add that the screws for each of the mounts were the same length, eliminating that variable as the problem.

April 23, 2007, 09:46 PM
The problem you have is not the top of the rifle, it is the length of the screws. Shorten them and all will be fine. Remove the "soft" shim too.

You will need to grind down the screws, they are too hard to file. It's difficult to hold short screws and grind so make yourself a sheet metal "gizzy" to hold them for you. Take a piece of sheet metal (steel is best but alum or brass will do) something like .025" or more thick and approximatly .5" wide by maybe 6-8" long. Drill a hole in one end that will just accept the screw's shank and then fold the metal so the ends match, trapping the screw head in place. Using your new gizzy as a pliers, grind off the needed length.

April 24, 2007, 01:57 PM
OK, gotta ask.....Why am I grinding screws for a rifle and mount that have been on the earth longer than I have? I have to assume that Weaver has worked out this bug long ago, so am I just having a quality control problem with some screws?

April 25, 2007, 01:22 PM
Solution found - purchased yet another entire scope mount and screws. Figured it was worth the gamble at $7. Lo and behold, the mount is on and no interference with the bolt. Looks like the previous mounts had screw holes of too large a diameter that would allow the screws to travel too deep into the hole.

A quality control problem.

April 25, 2007, 07:27 PM
Yeah, Opps...

April 25, 2007, 07:29 PM
Ohhh, did it agin..

April 25, 2007, 07:30 PM
Yeah, that's what I figgered, but not on Marlin's part. Grinding your first set of screws would have corrected the too long problem.

April 26, 2007, 10:59 AM
It has long been S.O.P., to check any rifle's scope mount screws, used in both through-holes and blind holes, for excess length & shortening as req'd, to prevent binding action parts - or a loose base, in the case of a too-long screw in a blind hole. :banghead:

The extra-length screws are a hold-over from the earliest days of scope mounting, over 50 years ago when scopes first started to become popular.

Most rifles were not D/T for the then-new-fad; many WWII vets didn't have the funds for a new factory rifle - so military surplus rifes, of all nations, were "sporterized" by chopping the stocks and mounting a scope.

The scope mount makers supplied longer screws, with the express purpose that they be fitted (shortened) for a particular rifle - since the several dozen different kinds of rifles, being scoped at the time, all had varying thickness of metal in the receiver(s). :cuss:

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