Rifle Came Back From Machinist...Claw Mounts Crooked?

[Tom H.]

Mike, I agree with everything that you said. I seldom change things that were right in the first place unless absolutely necessary.

I am sorry that I didn't take a better look at the bases. I didn't realize that both of them were drilled and tapped.

If I have it right, these are the aftermarket bases that are reversed and the scope is removed by taking out the bolt and tilting the scope to the rear. The release is on the front base.


So the first thing to check is that the holes are true.
If the holes are the issue, this is fixable (by the machinist who installed them) by tapping to a larger hole if necessary. I have installed a number of those mounts and the holes should easily clean up to 8-40. The larger tap will let you move the hole, and the base in the direction that you need to.

The easiest install is with a https://www.forsterproducts.com/prod...nting-fixture/ that aligns every hole that you drill with the flat on the bottom of the action. It also centers the holes to the bore if the action is true in the first place.

If the holes are correct and the bases are off, I agree with Mike and Diz's thoughts on removing metal to tilt the base into alignment. It appears that the rear base is lower than the front so removing metal from the front base should lower it enough to lock into place.
If the bases are crooked left and right, scraping or filing on one side or the other will tilt it into position

If the bases are correct, then the barrel can be turned a few degrees to solve the sight problem because that would mean that the rear sight was incorrect from the factory.


I have an Argentine sporter that I did this exact job with. I decided not to grind the charger bridge and used a large mill to remove metal from the rear base until it didn't hang up on the charger bridge. I contoured the rest with a Dremel cut off disk.

I can post pix if necessary.

Tom

[Diz]

Sometime ago, I had a rifle with the base on crooked very much like this one and as I remember I used some steel filled epoxy to level the base. I applied mold release to the action and then settled the base in until it was true and let it cure. Afterward, I cleaned up the epoxy and re-drilled the holes. It held up for years until I sold it. Just another thought. Thanks, Diz

[mike ford]

Tom,
I too have found myself in the position of having to relocate someone else's misplaced hole( if lucky- one per rifle). Typically, I plug the hole with a 6-48 screw, Loc Tited (red), and filed/polished to fit. Then drill/tap 6-48 in the correct location. I use an old B Square jig, located by running a tap through the tapping bushing into the correct hole, then locking it down. This places the jig in the correct location for the formerly misplaced hole. This way, I don't have to change the other screws to 8-40 or be stuck with one "off sized" screw. Changing all to 8-40 means they have to all be drilled and tapped, the bases have to be redrilled and counterbored. Just doing the one looks funny( not in everyone's opinion). Since the original screw was misplaced, the new one usually catches at least half diameter in the new location. I still can't see any advantage to tweaking the barrel, the open sights don't affect the scope and the scope doesn't affect the open sights. Everyone has different ideas about all this.
Mike

[mhutchinson]

Finally got the rifle back from the machine shop. Better news than I expected, honestly. Turns out the only problem was that the read mount is not tall enough and thus the scope ring was not in lined with the front ring. All it took was a 0.062" shim and it all lines up. Claw mounts are still tight and the release is stiff but I imagine it was all meant to be that way, and it'll become smoother with a thorough cleaning and some use. Funny how something as simple as that problem was still too much for me to determine with my naked eye and a straight edge. From eyeballing it (look at the initial pictures I posted) I was sure one of the mounts was off center.

So that's the good news. The holes were placed in the correct locations and these guys aren't complete hacks. But now the next challenge...

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The shim they made for now is aluminum. I guess they don't have the capability to contour a steel shim with their machinery because the contour of that part of the receiver isn't perfectly round. But the ideal solution, I think, will be to make a steel shim and have it welded to the scope mount so that I can then blend it all back together. The front mount does not fit the contour of the receiver perfectly so this might be a good time to try to fix that but I don't think there's enough metal that can be removed from the front mount to make it low enough. I think some height will need to be added to the rear mount. Honestly it sounds like a project that I don't really want to take on myself. I could contour a piece of steel to receiver by hand but making it precisely the correct height and keeping it all square and straight might be above my capabilities. Should I start looking for a gunsmith who can take on this project?

[mike ford]

mhutchinson,
Since the front base is .062" too high and doesn't fit the radius of the front ring; "there is no doubt in my military mind" that the mounts were made for some small ring Mauser( VZ33, G33-40, commercial, etc.), and you have them mounted on a large ring Mauser. The difference between the diameters of small and large rings is about .110-.120", therefore the difference between the radiuses is .055- .060". The rest is likely because the base radius is smaller and doesn't fit all the way down. There are a couple different ways to bring them together, but since your guy couldn't recontour the receiver bridge, I think the easiest thing for you to do is polish the edges of the shim, color it black, and shoot it like it is.
Mike

[mhutchinson]

Hey Mike,
Thanks for the reply. Turns out I have a Mexican Mauser action (my next project...only a year or so behind my anticipated schedule so far...) laying around so I tried putting the bases on it to see how they fit. The Mexican action only has 3 holes drilled for a one-piece scope mount and the front two holes do not have the correct spacing for this mount, so I could only get one screw in for each base.

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The contour on both bases is off a little. The contours match the Honold Mauser better actually. But I don't know that this Mexican action wasn't ground down at least a little bit. The front ring still has the crest so it couldn't have been ground down much but the rear bridge might have been. I have no idea.

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The height, however, appears to be just right. FYI those photos were taken with the rings tightened on the scope and the bases sitting flat on the receiver. I couldn't get the rear base tight enough (screw too long or threads need to be tapped, etc.) to put the whole thing together with everything tightened down. It did all click together when I tried to mount the scope into the rings but the rear claws would not seat fully into the base due to the above issue. So that's why I had to take the photos with that way. Anyway, it appears that your hypothesis is correct.

In light of that, I wonder now if my best course of action-if I want mounts that fit well on the Honold Mauser without much modification-would be to look for another set of claw mounts and get rid of these before I go messing with them any more. The only thing done to them so far is the light grinding on the front of the rear mount to clear the clip bridge. I'm frustrated by the idea of using an aluminum shim and painting it black to be honest. I know it would work just fine but for how much time and effort I'm putting into this rifle it would just screw up the aesthetics.

On another, related note, after getting confirmation that the scope mount holes on the Honold Mauser are accurately centered and eyeballing things more closely, I think the iron sights are canted. Like the barrel was screwed in a little more sometime after the initial build. I do think that the rifle was reblued at some point because the receiver and barrel appear to be nitre blued whereas some of the other parts look like they were rust blued. So that increases the likelihood that modifications were made after the initial build.

[mike ford]

mhutchinson,
It seems you would be able to use the mounts on your Mexican Mauser, or if you have a WW1 Kar 98 action, you could likely use the mounts on it. With regard to the hole spacing not fitting on the receiver ring, you could fill the offending hole( using method cited above) and re-drill and tap it. If the single hole in the receiver bridge matches one hole in the base, it would be simple enough to drill and tap another. The attachments didn't open up for me. With regard to getting rid of the mounts you have, that is entire up to you. No one else knows if the natural desire to save your investment( in time and effort as well as money) out weighs the exasperation or not. With regard to possible canting of the barrel, I suggest you examine the bottom side of the barrel/receiver ring to see if there are "witness marks"; and if so whether they are aligned or not. If there are no marks, I suggest checking by the two pieces of key stock method cited above. The "true surface" would be the flat bottom of the receiver( you will need to clamp the key stock). It is possible that the barrel is a "take off" from another rifle, installed to save it.
Mike