SVT-40 scope mount screwup...

commissar_lubi

commissar_lubi

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So I bought an SVT-40 scope mount and scope set and went about installing it, however I made the mistake of unscrewing a screw I was not supposed to touch. A cap and spring fell out of the mount per se (see pictures for a better perspective: https://imgur.com/a/xlh20 ). Despite trying many times to install the mount with the spring and cap reinserted into the circular slot it (I supposed) fell out from, the mount refused to slide in the length of the receiver grooves without a good push. If I forced it in, it would eventually slide back out (likely due to the already mentioned spring pushing against the receiver's back) so as to block the "hatch" at the end of the receiver and push the crosspin out of its proper position in the receiver notch.

As a workaround, I removed the spring and kept the cap. This way the mount and scope seem to be quite solidly installed in the right position (crosspin seated in the notch and back hatch able to open sideways properly without the mount blocking it) as it now slides in quite easily, however I'm rather concerned that I might leaving out a crucial part of the scope mount (i.e. the small spring).

Anyone have an idea what to do ?
 
marshall said:
I am thinking that the parts are not lined up properly when you put it togerther, if you have to leave the spring out
Click to expand...

That would make sense but the cutout at the back of the mount fits the cap perfectly, and the cap fits the spring. My guess might be that it's because I can't compress the spring enough to fit again... but then the spring would just push out the cap and up against the receiver again...
 
There is nothing to line up. You just have to push that cap in HARD to make sure it's in far enough for that set screw to catch it.
 
I found that spring way to strong. It was pushing the mount off the back of the receiver. So I cut a coil or two off it until it sat with the right tension.
 
Scarheart said:
I found that spring way to strong. It was pushing the mount off the back of the receiver. So I cut a coil or two off it until it sat with the right tension.
Click to expand...

Thanks for the input!
I considered doing that too, might actually give it a go if we can't get it to fit properly by force. Any idea what that spring does??
 
commissar_lubi said:
Thanks for the input!
I considered doing that too, might actually give it a go if we can't get it to fit properly by force. Any idea what that spring does??
Click to expand...

My understanding is that it acts as a recoil buffer for the scope/mount. It allows a slight movement of the scope/mount under recoil before resetting to the original position (in theory), thus reducing wear and tear on the scope/mount and "maintaining" zero.
Just my 0.02.
 
Mongo62 said:
once you put preasure on it and push it up into place and put the crosspin in it cant go anywhere. does the back of the receiver on your SVT have the cross slot cut?
Click to expand...

yes it does have the notch to fit the crosspin! I've tried to push the spring/cap back but it would end up pushing against the receiver and push knocking the entire mount off (to the point the pin would ride on top of the notch...)
 
commisar_lubi: I had one repro mount whose spring was way too strong. I believe I put the spring in my vice and used a hacksaw blade to cut a couple of coils off it. The original design does appear to have been intended to buffer the scope during firing by allowing the scope/mount to slide forward during recoil with the spring pushing the scope/mount back into battery. I'm not sure it's universal but I've found (with three mounts) that the cross-pin is up too high relative to the original spec notches on real sniper versions. Is yours an authentic sniper or has a notch been filed in by yourself or a previous owner? If it's original, watch for that pin damaging the rear lip of the notch. The receiver, in that area, is quite soft and only a few shots will deform the notch if ther pin is too high.

milsurpo
 
even pushing the pin in if you arent carefull can wear the back of the notch. I scraped a tiny bit of receiver notch getting min in the first time.

Ive been puttinga couple pieces of brass shim at the rear of the notch to create a bigger shoulder for the cross pin to hold against as well as move the mount more forward to keep it centered. it was too sloppy otherwise. Also the brass shim protects the receiver from gouging. it is increadably difficult to remove/add the mount now tho because the shim tends to move unless you have an extra pair of hands to help.
 
I found that the holes in these repro mounts are not in the correct place, they are too high and the pin will be damaging the notch.

On mine I ended up filing the hole out lower with a rat tail file and making a new cross pin for it so that everything lines up properly now.
 
M1-Garand said:
I found that the holes in these repro mounts are not in the correct place, they are too high and the pin will be damaging the notch.

On mine I ended up filing the hole out lower with a rat tail file and making a new cross pin for it so that everything lines up properly now.
Click to expand...

Could your mount move/wobble as a result of the crosspin hole being set too high or was it still solidly fixed?

Mine actually locks solidly in place with the crosspin in so I guess it's ok?
 
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I tried every mount I could find on several SVT's. Was not happy with any of them.
One was sold a few years ago, the square one. There were I think 3 clamp bolts and I tightened those suckers up till they squeaked.

Then, on firing the rifle...the mount moved forward on each shot, till the bolt carrier handle started hitting the mount. This despite the clamp bolts being extremely tight. So, you had to keep moving it back

Then the corrosive ammo turned the bore dark, even though I cleaned it immediately with boiling water and bore cleaners of various types.

I hate those rifles. Sorry.

As for this situation, the spring plunger on the rear of the repro mount was to return it to it's spot after the recoil of firing. I'd do what M1-Garand above did, file the hole lower and make a new pin. (if the hole is too high)

The worst thing is, you have to clean the rifles immediately after firing, and that means the mount has to come off. As for holding zero...
The Russians stopped using them as sniper rifles after a while I believe.

Best setup is probably to install a side mount Dragunov style scope. Not stock but a lot better.
 
I used a Dremel tool with a cut off disk. Those springs can damage a pair of side cutters.
The repro scope mount is like the repro mags. Not exactly to spec. The actual vintage stuff works well if you can find it.

commissar_lubi said:
How did you cut the coils off, i'm trying right now and it's quite a hassle
Click to expand...
 
commissar_lubi said:
Could your mount move/wobble as a result of the crosspin hole being set too high or was it still solidly fixed?

Mine actually locks solidly in place with the crosspin in so I guess it's ok?
Click to expand...

The mount did not wobble,it fit nice and snug on the receiver,but once I started shooting it became evident that the cross pin was damaging the back of the notch.
If you remove the spring and slide the mount on you can look through the hole and see it is not lined up with the notch,too high,that's why I modified mine.
 
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