Some of us have been fascinated by the Swiss K-31 C&R rifles. They are very fine rifles, well built, and shooting very accurate ammo.
The military sights on the rifles are excellent sights and I can shoot them about as well at 50 yards as any rifle I own. But these eyes need a little help at 100 yards. I just can't do as well with iron sights as I can with a scope at 100 yards.
There is a great scope mount for the K-31.
It isn't too expensive and works like a charm.
I bought one from Brownell's and installed a scope on the rifle.
The clamp-on mount cost $60.22 and the scope rings (1" high) cost $15.30.
Here it is.

It is a Tasco scope, a 4 X 16 X 40mm scope.
Not expensive, but a good scope, with parallax adjustment.

As you can see, it mounts slightly to the side, allowing the loading of the magazine from the top.
It is slightly to the right side, but not so much that it is difficult to get a good cheek weld.

The mount has an ingenious single-point clamp-on mounting system, that does not mark the rifle in any way.
The single point is best adjusted all the way forward on the side of the action and then clamped down.
Here's the inside of the clamping system.

Here's what it looks like on the outside.

Here I am, sighting the scope in.
It took very little adjustment to get it on at 50 yards.
We then moved the target out to 100 yards.

Here's the first 3 shots at 100 yards.
A nice 1 MOA group.

I adjusted the scope to move the group over about 1 1/2 inches, and we are good to go.
It was cold and a little windy today, so we didn't do too much shooting for groups, but will do so when the wind lays down a little.
The last day we shot it, it was windy and we were not able to really see how well it would shoot.
I went this morning and tried it again.
It is the first time I go to the range since Turner left.
It was kind of hard to do. But I believe Turner would want me to continue to shoot and post.
So, I dedicate this one to Turner.
And here I am shooting it at targets set at 50 yards.

We will be shooting standard Swiss military surplus 7.5mm ammo, which is actually as good as any target ammo I've ever seen.

Here's the first 5 shot group.
If I had not dropped that last round on the bottom, they all would have gone into the same hole.

Here's another two 5 shot groups, with different points of aim.

And the last two 5 shot groups, and a little hint on using a square bullseye.
Notice that the knife point is pointing at the lower left corner of the bull.
This gives a clear point of aim, better than the vague center of the bull, a trick I learned from my buddy Brianksain.
We used the upper and lower left points of the square for the POA for the two groups.
The POI is purposefully moved to the left so as not to destroy the POA.

All groups were 3/4 inch or less with the smallest just over 1/2 inch. Not bad for an old rifle, with old milsurp ammunition, and old eyes.
Conclusion:
These fine rifles are great shooters and very accurate, with or without a scope.
They are a joy to own and shoot. If you don't have one, you need to get one.
I'd sure hate to have a Swiss sniper shooting at me with one of these fine rifles.
The military sights on the rifles are excellent sights and I can shoot them about as well at 50 yards as any rifle I own. But these eyes need a little help at 100 yards. I just can't do as well with iron sights as I can with a scope at 100 yards.
There is a great scope mount for the K-31.
It isn't too expensive and works like a charm.
I bought one from Brownell's and installed a scope on the rifle.
The clamp-on mount cost $60.22 and the scope rings (1" high) cost $15.30.
Here it is.

It is a Tasco scope, a 4 X 16 X 40mm scope.
Not expensive, but a good scope, with parallax adjustment.

As you can see, it mounts slightly to the side, allowing the loading of the magazine from the top.
It is slightly to the right side, but not so much that it is difficult to get a good cheek weld.

The mount has an ingenious single-point clamp-on mounting system, that does not mark the rifle in any way.
The single point is best adjusted all the way forward on the side of the action and then clamped down.
Here's the inside of the clamping system.

Here's what it looks like on the outside.

Here I am, sighting the scope in.
It took very little adjustment to get it on at 50 yards.
We then moved the target out to 100 yards.

Here's the first 3 shots at 100 yards.
A nice 1 MOA group.

I adjusted the scope to move the group over about 1 1/2 inches, and we are good to go.
It was cold and a little windy today, so we didn't do too much shooting for groups, but will do so when the wind lays down a little.
The last day we shot it, it was windy and we were not able to really see how well it would shoot.
I went this morning and tried it again.
It is the first time I go to the range since Turner left.
It was kind of hard to do. But I believe Turner would want me to continue to shoot and post.
So, I dedicate this one to Turner.
And here I am shooting it at targets set at 50 yards.

We will be shooting standard Swiss military surplus 7.5mm ammo, which is actually as good as any target ammo I've ever seen.

Here's the first 5 shot group.
If I had not dropped that last round on the bottom, they all would have gone into the same hole.

Here's another two 5 shot groups, with different points of aim.

And the last two 5 shot groups, and a little hint on using a square bullseye.
Notice that the knife point is pointing at the lower left corner of the bull.
This gives a clear point of aim, better than the vague center of the bull, a trick I learned from my buddy Brianksain.
We used the upper and lower left points of the square for the POA for the two groups.
The POI is purposefully moved to the left so as not to destroy the POA.

All groups were 3/4 inch or less with the smallest just over 1/2 inch. Not bad for an old rifle, with old milsurp ammunition, and old eyes.
Conclusion:
These fine rifles are great shooters and very accurate, with or without a scope.
They are a joy to own and shoot. If you don't have one, you need to get one.
I'd sure hate to have a Swiss sniper shooting at me with one of these fine rifles.