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Find different scope, drill & tap again orů?

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Find different scope, drill & tap again orů?

Old 11-01-2010, 06:08 AM
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Nontypical Buck
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Default Find different scope, drill & tap again orů?

I have a Marlin 512 Slugmaster, which is a 12-ga slug gun (rifled barrel). I bought an inexpensive scope for it the other day (used Weaver K4, 4x38), but I found that it is not really usable with the gun in its current configuration. I purchased the K4 because I got a smoking good deal on it and Weaver is renowned for the accuracy of their adjustment knobs (so as not to make sighting in more expensive than it has to be). The ONLY scope mount that the Slugmaster will take is this Weaver:



Notice how narrow the space is between the two rings. That means you cannot move the scope very far towards or away from the muzzle before the adjustment knobs hit one of the rings. The K4 is a very normal-sized scope with average eye relief, but because of the position of the taps on the receiver (too far forward IMO) and the limited space between the rings, I cannot slide the scope toward the breech enough to get a good FOV without doing some serious rubbernecking. And that is without the added layers of bibs and coat, etc…just in a t-shirt. This is just a picture from the internet to give you an idea. This is the same gun I have but the scope pictured is much smaller, but the objective lens on this one is as far back as I can get mine to go:



In order to fix my problem, I need a scope that has the adjustment knobs well forward of center. The problem is, I only paid $75 for the K4 in almost perfect condition, it’s pretty much the exact scope I was looking for (accurate adjustment knobs being top of the list), and I don’t want to spend much more than that (and I would have to sell the K4). I also don’t want to lose 38mm FOV to something smaller.

So, I am thinking that I should have the threads for the scope base moved back an inch or so, unless there is another solution. This would probably leave two threaded holes exposed once the base was moved back towards the breech, and the holes are drilled all the way through the receiver to the channel where the bolt slides back and forth. The exposed holes probably won’t be an issue though. Not sure I can get this done quickly though, as I’m sure all the gunsmiths are slammed at this time.

What would you do?

Last edited by 7.62NATO; 11-01-2010 at 08:37 AM.
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Old 11-01-2010, 10:29 AM
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Was looking through the Brownells catalog and noticed they have a long and short side mount ring that fit your base. The short side mount rings have 1.8" between the rings, and the long side mount rings have 3.7" between the rings. If an extra inch will mount the scope in the correct position, then you're in luck.

Part number: 955-493-303 www.brownells.com
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Old 11-01-2010, 11:49 AM
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Thanks for the response! Is this the one you mean?

At first, I was excited! But I don't think it will help me. Tell me what you think. The rear hole for the screw sits farther behind the rear ring than it does in the mount I have. So, that puts the ring farther forward using this mount, correct? Maybe I'm not thinking of it right, but it makes sense to me.

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Old 11-01-2010, 11:56 AM
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Actually, this has got me to thinking. The base plate for the mount is secured to the receiver via 4 screws. I could remove it from the receiver and slide it towards the breech just a little, securing it only by two screws though. This may or may not work...a slug gun generates a lot of recoil, but if the screws are tight, they're tight, and using threadlocker should keep them in place.

Another thing, is that I could simply drill two new holes in the mount I have, as far forward as possible. That way the base plate is still secured by all four screws and that would move the scope rearward...hopefully enough. Obviously about an inch would be lacking contact on the base plate, but I think there would be enough contact for it to hold properly. The holes in the mount are not tapped, so it would make for a much easier job. All I need to find is a drill press.

Does this seem doable to anyone else?
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Old 11-01-2010, 02:49 PM
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Originally Posted by 7.62NATO View Post
Actually, this has got me to thinking. The base plate for the mount is secured to the receiver via 4 screws. I could remove it from the receiver and slide it towards the breech just a little, securing it only by two screws though. This may or may not work...a slug gun generates a lot of recoil, but if the screws are tight, they're tight, and using threadlocker should keep them in place.

Another thing, is that I could simply drill two new holes in the mount I have, as far forward as possible. That way the base plate is still secured by all four screws and that would move the scope rearward...hopefully enough. Obviously about an inch would be lacking contact on the base plate, but I think there would be enough contact for it to hold properly. The holes in the mount are not tapped, so it would make for a much easier job. All I need to find is a drill press.

Does this seem doable to anyone else?

Maybe this can help.

http://www.midwayusa.com/viewProduct...tNumber=898916

Product #: 898916
Attached Thumbnails -product-898916.jpg  

Last edited by jrbsr; 11-01-2010 at 02:58 PM.
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Old 11-01-2010, 04:03 PM
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Nontypical Buck
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No, the rings on the Weaver mount are part of the mount itself.
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Old 11-01-2010, 05:11 PM
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I ques you will have to get another scope, or take it to let a gunsmith look at it.
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Old 11-01-2010, 09:40 PM
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Another thing, is that I could simply drill two new holes in the mount I have, as far forward as possible. That way the base plate is still secured by all four screws and that would move the scope rearward...hopefully enough. Obviously about an inch would be lacking contact on the base plate, but I think there would be enough contact for it to hold properly. The holes in the mount are not tapped, so it would make for a much easier job. All I need to find is a drill press.
That seems to be the easiest and simplest method to try. You could also pull the base plate and drill and tap two holes closer to the rear to move your rings rearward.
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Old 11-06-2010, 06:47 AM
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I'd recommend getting a special slug gun scope. They would resolve your problem due to the scope offering a lot more eye relief. Then you could use the existing mounts.
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Old 01-08-2011, 05:47 AM
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I would try to sell the scope and get another one. By the time you pay a competent gunsmith to drill and thread to move the mount you are going to have that much more money invested. Is $75 that good of a deal on a used Weaver K-4 4x38?
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