So, are FN Mauser bases the same for using on a de-humped 98? I don't have a FN to compare but have five 98's I would like to put two piece bases on de-humped.

usually. I have been confronted with the rear bridge not actually being the proper contour or height depending on who de-humped the action.

quote:

Originally posted by max(hm2):
usually. I have been confronted with the rear bridge not actually being the proper contour or height depending on who de-humped the action.

Good point, some have really be "bubba'ed"

Ditto the last two posts. If the front ring has been ground on you, can add another issue. In any case, I recommend that once you have the receiver and rear bridges contoured to your satisfaction, take your caliper and measure from the receiver bottom flat to the top of the rear and front rings. Then add those measurements to the thickness of the front and rear bases at the screw holes. Make sure when you do this that the bases are flush to the metal at the screw holes and not riding up on their edges. IOW's, make sure the inside radiuses of the bases match the receiver. The measurements should be pretty close. If not, shimming is in order.

The reshaping or removal of the clip guides should not affect the receiver contours, if there is a difference of height it was built that way since the reshaping will use the existing shape to indicate the receiver prior to grinding, in essence you blend the new profile into the rest of the rear bridge. In my experience there should only be contact between the scope base edges and not with the high radiused point on the rear bridge, similar to what Talley does with their bases. You should measure the height differences before starting your work or installing bases in pre contoured actions. Having full contact in the rear is iffy at best.
BB

If I remember right, I believe the rear bases for military 98 and FN's have different hole spacings because of the clip slot

Typically, the bases marketed as fitting unaltered 98's have a narrower hole spacing on the rear than an FN type.

Assuming that the Milisurp rear bridge was properly recontoured, then yes, an FN base will fit. Problem is, all too many are contoured by a yokel with a belt sander or free handeded such that they aren't level or of the same contour as an FN bridge.

I only use FN bases for all 98 Mausers.

Your choice will be what rear hole spacing you choose since the contour and height of the rear bases is the same, their length will also vary, the front bases are the same.
BB

Thanks for the replies. I'm going to try one of these to see if I like it:

https://www.amazon.com/CCOP-SB...8&returnFromLogin=1&

You can buy bases to fit both from most if not all the base makers or you can grind the rear base then drill and tap to fit..Best option iMO on a good Mauser is to have it surface ground and proper bases hand fitted.

Of the six unmolested 98's I have the bridges are ALL over the place in terms of symmetry. Some have no flat anywhere (varying curvature all the way 'round) and one, a German 1938 243, is hollowed slightly on the port side. Now, I'm ready for the slings and arrows, but seems to me that a filled epoxy is the way to go for final fitting; 100% contact.

quote:

Originally posted by copperlake:
Of the six unmolested 98's I have the bridges are ALL over the place in terms of symmetry. Some have no flat anywhere (varying curvature all the way 'round) and one, a German 1938 243, is hollowed slightly on the port side. Now, I'm ready for the slings and arrows, but seems to me that a filled epoxy is the way to go for final fitting; 100% contact.

Sure.

Or, you could do it right and profile it correctly.

Well, I'm sure few of the military Mauser pattern makers paid much attention to rear bridge contours and relative heights. Most need some adjustment to get good, level mounts. I once had a M1909 action contoured by a 'smith in Lakeland, FL. He was a retired master machinist turned gunsmith. His name was J.D. Ballinger. He used a milling machine to do the rear bridge and it is perfect. He also made sure the bridge/ring height differences were correct to match the bases. Top notch fellow.

I don't know where the bases from Amazon are made but they look like communist copies of US made Leupold. Which is what I recommend you use.
Another thing; Leupold one piece bases are much easier to install for those drill alignment challenged (not suggesting anyone here is by any means). And they only require three holes and are almost impossible to get wrong. I use a lot of them. I even put them on Mosin Nagants; completely off topic but just thought I'd throw it in. One piece Leupold bases that is.
Now, fitting bases to Mausers is not rocket surgery but it seems that many still get it wrong.

I'll second that!

quote:

Originally posted by dpcd:
I don't know where the bases from Amazon are made but they look like communist copies of US made Leupold. Which is what I recommend you use.
Another thing; Leupold one piece bases are much easier to install for those drill alignment challenged (not suggesting anyone here is by any means). And they only require three holes and are almost impossible to get wrong. I use a lot of them. I even put them on Mosin Nagants; completely off topic but just thought I'd throw it in. One piece Leupold bases that is.
Now, fitting bases to Mausers is not rocket surgery but it seems that many still get it wrong.

I'm not a gunsmith but someone concerned with scope integrity. Even if the nominal heights can be gleaned by measuring receiver rings, what really matters is where the scope points when the reticle is optically centred.

People put lots of money into rifles and scopes; I just wish they would give the craftsman his due and spend some getting these things mated by someone who knows what he/she is doing.

Second, despite much opinion seen to the contrary, I like dpcd's outlook on bridge mounts.

You are right; it doesn't matter where the scope is actually pointing as long as you can get the reticle to zero it.
As for non centered holes, they are pretty common for lots of reasons. either the driller was careless, or he used one of the old school fixtures that only holds the barrel; a guaranteed way to have 25% of your holes off. I use no fixture even though I have two of them; I level and true each base and hole individually. Yes it takes longer....
Case in point; I just fixed a Mauser that someone had drilled the front holes off center. No scope had enough reticle travel to make it zero, so I welded up the base holes and re drilled them; perfectly centered.
It only matters if you like to crank your reticle back and forth for some unknown reason, but some guys do.
Now, on the pre 1960s scopes with non centered reticles, then having the reticle set far off to one side would not be good. Still works though; just the target is never centered. But modern scopes all have centered reticles.

Yes, dpcd, getting the reticle centred could be a problem way back but once you did at least there was no mini-me scope bouncing around inside when you touched off.

The answer may be coming, though: an optics researcher in your country has invented a scope that centres the reticle without recoil-movable bits or the Pecar solution (a field stop around the reticle).

I recall seeing a lathe mounted grinding jig online somewhere. Blueprinting is hard to beat if you can find someone who does it frequently. No filler.

quote:

Originally posted by copperlake:
Of the six unmolested 98's I have the bridges are ALL over the place in terms of symmetry. Some have no flat anywhere (varying curvature all the way 'round) and one, a German 1938 243, is hollowed slightly on the port side. Now, I'm ready for the slings and arrows, but seems to me that a filled epoxy is the way to go for final fitting; 100% contact.

I believe a scope should have the cross hairs centered in the focal plane to start with then mounted to bore sight at least, leaving full adjustment available..You can center the X to poi, but it may well be on the edge of the scopes adjustments and that shoddy work..and a good place to start is a surface ground action with that in mind..

Yes, Ray, and it seems to me that in low-powered scopes, if you can get one mounted to bore sight without touching the knobs, subsequent clicks to get on target rarely show even in old reticle-movement models. Even if getting more elevation does take the posts a bit lower in the field, I can live with that. It's only lateral displacement that gets my goat - and windage mounts usually fix that.