Saturday, February 11, 2012

Marlin 60 Owners Do NOT Overtighten Your Scope Rings!


Man, do I feel STOOPID or what!
I wanted to go to the range today to practice with my Marlin 60. The first time I took it out, the open sights were WAAAAY off! Consistently up and to the left. I'd since ordered a set of "Tip Off" scope rings to fit the dovetail grooves in the receiver, and put them on this morning so I could use the little Simmons 2.5x20 scope I had laying around.
I slipped the rings onto the receiver, and tightened them down.
TOO well it turns out.
I heard a small "SNAP", and noticed the rearmost ring seemed loose, and then I noticed I had broken off a piece of the dovetail!
DUH!
I guess I'm just too used to guns being made of steel, and I'd forgotten the receiver on the Marlin 60 is Aluminum.
CAST Aluminum.
Castings aren't nearly as strong as forgings, or machined billet pieces, and this, coupled with the design of the receiver top, made it, uh..., not very strong, and when I cranked down on the screws that secure the mounts in place, it failed.
If you look at the pictures, you'll noticed the grooved top of the receiver. This means there's hardly any metal on the "back" side of the dovetail for support, so the metal just cracked and pulled away when I tightened the rings down.
Do I consider this a design defect? Yes.
Do I consider this a "Stupid Owner" error? Also yes.
I was able to move the rear ring forward enough that I was able to get the scope mounted for today's range session, but I'm really bummed I did this to my poor little Marlin 60.
Yes, I knew the receiver was Aluminum alloy, and probably should have known it was also a casting, given the price of this rifle.
I mixed up some JB Weld when I got home, and used it to attach the broken off piece, so at least I don't have a raw Aluminum scar staring me in the face every time I pick up the rifle.
And the range session? Terrible. First, the place was packed, and I had to wait. That part I don't mind because I'm glad to see them doing a good business. But a lot of the people there weren't very disciplined, there was brass all over the floor, and the guys in the next lane were doing rapid fire with what sounded like a 44 Magnum, and I just couldn't concentrate.
And even with the small scope, I still couldn't hit diddly squat with this thing. I just didn't have the patience today to try and zero the scope, so after 50 or 60 rounds I just packed it up and came home.
Bad day........

8 comments:

  1. drjim,

    That's what we used to call a bummer man. Not sure what to tell you to do.

    Regards,
    PolyKahr

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  2. Yeah, kinda surprised me when I did it.
    Well, it still shoots safely, and nobody got hurt (well, my pride kinda stings!), so I just have to chalk it up to experience.

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  3. Ouch! Sorry to hear about this!

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  4. Wow! What was at the make and model of the rings you used?

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  5. I don't remember what brand of rings they were. I think I bought them at the local Turner's Outdoorsman store.
    I'm sure you could snap the cast aluminum rails on the receiver with just about anybody's tip-off rings.

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  6. Just found your blog after doing the same thing to my brand new Marlin 60. Like you, I feel like even though I'm the one who overtightened the bolts, the dovetail should not have failed from the limited amount of torque I put through the allen wrench. I didn't even know it was made of aluminum and never would have guessed it was so fragile. Marlin tried to do too much with too little, and as I see it this is a design flaw. I guess I need to invest in a small torque wrench before attempting something like this again.

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  7. I knew it was made of Aluminum, but didn't suspect it was CAST aluminum.

    A machined piece, obviously with a different alloy, would have bent before it failed.

    So far the JB Weld is holding, and after I cleaned all the screws and threaded parts with some Gun Scrubber, I put it back together using a bit of green LocTite.

    It seems to be holding just fine, but then there's not a lot of recoil from a 22LR!

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