Mosin PU mount - stripped screws, need info

H Wally

H Wally

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In what turns out to have been a misguided purchace, I am now rebuilding a PU scope mount and base setup. I got it second hand, and have been slowly discovering many of the unmentioned damages to the assembly.

Most recently I've turned my hand to repairing the damage to the vertical adjustment screws. The screws themselves are very stripped, and the upper of the two threaded holes on the mount is slightly stripped as well. In addition to this, it looks like the former owner or "gunsmith" put in sightly small screws.

Anyways, since I don't have useable screws to copy or check, does anyone know the details on the correct threading for the vertical sight adjustment screws? I'm going to make some more once I get that info, and if the base itself is too stripped out I'll just put a helicoil in. Since everything is already mounted to the gun it'll be more straitforward to do this than to strip the mount off and redo the whole deal with a new scope assembly.

Thanks in advance.
 
Don't believe so, unless you're talking a cast then milled repro...

It has milling marks on it - I assume it's from east wave or one of the similar importers.
 
Yah - from the looks of it, the former owner tried to change the elevation by trying to screw the top screw in, without loosening the bottom screw. If a gun smith did this, I hope he's long out of business, because there're a lot of small, fixable, but incredibly stupid problems...
 
Hmmmm - still no luck in getting screws. I think I'll have them made. Anyone out there know more about the pitch and threading on these screws? Mine are pretty much bare.
 
All the screws I've dug up have been too coarse. I contacted accumounts and he wants $5/screw plus shipping... on the one hand, it's a business and it needs to be worth his time, on the other.... $5???


I've been looking for a fine tap and die set, but none are that diameter or close without being really coarse.
I got some 1/4 inch diameter 28 thread/inch set screws, but they're pretty darn big.

Since I've got 0 experience with scopes, or working PU scopes, anyone think this coarse a screw could cause issues with fine vertical adjustments?

I've got a tap for 1/4 inch 32thread/inch, but no die or screws...and looking at it right now I think the tap was dropped, because there appears to be a crack.... damn....

So, opinions? I'd be ok with 1/4 x 28 if people think it'll do the job. I just don't want to bugger this up and have to buy a whole new base.
 
Hey Wally, I wonder if this guy could help:
ht tp://www.customscrewsandmore.com/default.html

I have a heard time picturing in my mind the exact details of the problem, would you have a pic that we could look at? Maybe it's just that my brain isn't up to the task of reading and transferring these words into a mental image (neurons aren't responding much this morning)

Lou
 
This is the exact Mosin PU Base.

You are looking at it from the left side of the rifle, with the butt to your right and barrel to your left. There's little depth of field, but just above and below the right screw and set screw there are two ears that project outwards that are threaded to accept the vertical adjustment screws.

59_PU_base_27.jpg


Here's an sks version of the same mount - you can see the screws and ears much more clearly

p3230203ix8.jpg
 
You could allways use new screws like these, Im going to use them to fill in the 2 empty holes that were orignaly made for the pins.

If you need some PM me you adress and I can send somme to use...

I just cant wait to put this on my M44...

IMG_5795.jpg
 
I've got some set screws, but the issue there is that they're way coarser than the ones that are supposed to be there.

To reiterate earlier posts - anyone think a 1/4 inch by 28 threads per inch screw would significantly affect how I used the rifle? I'm pretty sure fine vertical adjustments would be more difficult when zeroing... but I guess I could always reset the "0" on the scope reticle itself to deal with this.

Opinions?
 
Ok I think I understand, thanks for the pics wally. So the issue is with the screws located in the "ears" (from your description's "there are two ears that project outwards that are threaded to accept the vertical adjustment screws") - and adjustment is made by screwing one in, and the other out, thereby raising or lowering what's stuck between the two screws.

I think your approach (make a new thread in these two holes) could work if the steel is of good quality and there's enough extra for a slightly larger hole? I wonder if the bits from a tap and die set would be good enough for the job.

Lou

Lou
 
H Wally said:
I've got some set screws, but the issue there is that they're way coarser than the ones that are supposed to be there.

To reiterate earlier posts - anyone think a 1/4 inch by 28 threads per inch screw would significantly affect how I used the rifle? I'm pretty sure fine vertical adjustments would be more difficult when zeroing... but I guess I could always reset the "0" on the scope reticle itself to deal with this.

Opinions?
Click to expand...

I think 1/4-28 should be fine. The vertical adjustment is just to get the scope in the ballpark anyway. Since the top and bottom screws are both tightened against the mount and pinch it in place, and it's only set once and then left alone, can't see it mattering. Main issue is good, strong, non stripped threads.

The issue on these mounts is the windage, not the elevation. The elevation is the easy part.

I sure wouldn't pay Accumounts $5 for some Chinese screws that probably don't fit anyway.

It's a little bit non traditional? What the heck, it's not an original sniper anyway.
 
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