Problem with scope bases on FN 98 receiver

mosinmaster

mosinmaster

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So, I have a Husqvarna 640 that's built on a FN 98 receiver. I ordered the weaver bases for a FN98 which are #45 rear and #46 front.

I installed them, and then I noticed that they aren't at the same height. I tried a pair of Leupold PRW rings and the heights between the two are different. I'm not sure exactly if the #45 rear is meant for a military Mauser with a charger groove? Any help appreciated.

eudxG46.jpg
 
mosinmaster said:
So, I have a Husqvarna 640 that's built on a FN 98 receiver. I ordered the weaver bases for a FN98 which are #45 rear and #46 front.

I installed them, and then I noticed that they aren't at the same height. I tried a pair of Leupold PRW rings and the heights between the two are different. I'm not sure exactly if the #45 rear is meant for a military Mauser with a charger groove? Any help appreciated.

eudxG46.jpg
Click to expand...


The #’s seem right from my many scope and base installs while working at everybody’s most hated gun store (Wholesale Sports).

I wonder if it’s because it’s the FN? I’d check the Weaver website if there are exceptions on your rifle (something rings a bell here but it’s been 15 years for me).
 
I get the feeling that there may be a different rear base for an FN "Commercial" action vs an FN 98 "military" action? The high #45 rear seems to make me think that on military actions, there's a dip in the rear receiver ring due to the stripper clip guide. Thoughts?
 
mosinmaster said:
I get the feeling that there may be a different rear base for an FN "Commercial" action vs an FN 98 "military" action? The high #45 rear seems to make me think that on military actions, there's a dip in the rear receiver ring due to the stripper clip guide. Thoughts?
Click to expand...

This! Yeah it rings a bell and remember sometimes on certain models, we had to either shim or shave off some material on the bases to make it work.
 
Same thing happens with Zastavas (also a FN pattern) I use Leupold Std rings. You could also shim.
 
Ah that explains it!

Now if they could only stop drilling the front and rear holes so off center from each other haha
 
The correct bases for an FN98 with a receiver ring of about 1.410' in diameter are a rear base #45 and a front base #46.

The Husqvarna with a receiver ring about 1.300" in diameter uses a rear base #55 and a front base #46.

Weaver does not list bases for the M98 as the M98 is not drilled and tapped... plus the rear of the action requires an alteration or the base used requires alteration.

The designation FN98 refers to the commercial 98. M98 refers to the military 98.
 
Based on Weaver's charts, the M96 action uses a #55 rear base. Thanks for the clarification. A bit annoying that Weaver lists under the FN 98 action #45 and #46 which is for the Military 98 action.
 
Weaver lists the 45 and 46 bases for the old Browning Bolt Action, High-Power... which is a commercial FN98 with a front receiver diameter of about 1.410".

The old Weaver chart I have does not list bases for the M98... the military 98... but many times the 45 and 46 have successfully been used on the M98 with a front receiver diameter of about 1.410".
 
I measured my front receiver ring as 1.41" with the calipers. I think a #55 base will work on this commercial as it has the same dimensions as the #45 except the thickness/height is 0.310 vs 0.396, or 0.086 less. Some reading shows that #46/#55 works for the Sears (JC Higgins) Model 51L which is a Husqvarna 640 (same as my rifle) both using a FN98 receiver but the Sears was meant for the American market.
 
Post back your results when you get it going...

With the action level in a vise, and a straight edge across the two bases, is the straight edge level or slightly high at the rear? You want it high at the rear... pointing the scope slightly down into the bullet trajectory. Level uses up too much of your elevation adjustment.
 
mosinmaster said:
I measured my front receiver ring as 1.41" with the calipers. I think a #55 base will work on this commercial as it has the same dimensions as the #45 except the thickness/height is 0.310 vs 0.396, or 0.086 less. Some reading shows that #46/#55 works for the Sears (JC Higgins) Model 51L which is a Husqvarna 640 (same as my rifle) both using a FN98 receiver but the Sears was meant for the American market.
Click to expand...

640 came in 96 and 98 actions, they used 96 when the war was on and 98's after, kept the same model number.
Anyway, the 45/46 are what is correct for a 98, eyeballing doesn't really help matters, throw a scope on it and go shoot before changing anything.
Here are a few 98's, yes the rear looks high, but that's the way it is.
20170414-164604.jpg

20170520-164335.jpg

20170803-131905.jpg

20190807-173934.jpg
 
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I did lay the scope down and the front end tilts down, hence why I posted this question. I don't want to crush the scope :S

I did a bunch of research and the 1640 action uses the same rear receiver ring dimensions as the 640 (Husqvarna FN 98).

My rifle is definitely a Model 98 with #### on opening. Serial puts it at 1952 when Husqvarna was transitioning from FN 98 receivers to their 1600 series action.

Combinations that should work are #46/#55 or #20A/#55. I'll probably do a bit of measuring of the receiver ring heights and pick which bases best approximate. I didn't know there was so much variation even in commercial mauser actions.
 
mosinmaster said:
I did lay the scope down and the front end tilts down, hence why I posted this question. I don't want to crush the scope :S

I did a bunch of research and the 1640 action uses the same rear receiver ring dimensions as the 640 (Husqvarna FN 98).

My rifle is definitely a Model 98 with #### on opening. Serial puts it at 1952 when Husqvarna was transitioning from FN 98 receivers to their 1600 series action.

Combinations that should work are #46/#55 or #20A/#55. I'll probably do a bit of measuring of the receiver ring heights and pick which bases best approximate. I didn't know there was so much variation even in commercial mauser actions.
Click to expand...

1640 uses '96 bases, not '98 bases.
This is the tread if you want lots of HVA info.
https://www.canadiangunnutz.com/for...796-Husqvarna-Sporting-Rifles-####-ALL-MODELS!!!
 
So the 1640 uses #46/#55 and a M98 uses #46/#45. I'm not sure about why I have #46 and #45 yet the scope ring heights are not even close to one another. I scoured the depths of the internet looking for people with similar issues, and I came across both large and small ring Mauser 98 receivers. Yes, not a Pre-98 model small ring mauser (93, 95, 96 etc.), but actually Model 98s with different receiver ring sizes. And apparently the Swedes did use a smaller ring variant, so perhaps why the #46 is too high as it's meant to match up with a large ring 98.

HVAscopechart-Oct22-092.jpg


Within this thread, Baribal, our HVA guru states that the 1600 series rear receiver shares the same dimensions as the 640 (FN98) action. So that's why I'm leaning more towards the same #55 base to get lower height.

https://forums.gunboards.com/showth...-Chart-Apeture-Sights-Updated-January-15-2011
 
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640 came in '96 and '98 actions, depending on the year of manufacture.
A '96 640 would use the same 2 piece bases as the 1600 series.
A '98 640 would use 2 piece bases for any commercial '98.
It shows them both in your chart above as well...640 '96 and 640 '98.
 
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