OK guys, I have all the parts and Im ready to install the mount.

A quick view of the name brand 'Ultra Dot' red dot scopes gives a length of 5.1"..... Say- 5-1/8"th.

Kinda sounds like someone altered one of the mount holes.

Don't know if this will help but hope so.

Over time Weaver has changed locations and ownership several times. Also model numbers. The most current info on the side mount and the two scope mounts are included below.

I have one of the previous models of the long scope mount with 1" rings. Included in the box is an instruction sheet. I scanned it and it's available as a download below. On the bottom of the back of the page is the info below on the side mounts. The one for the Universal and GI carbines was the Model M back then.

For a perspective of the broad range these mounts I have will fit, some of what I have owned have included the following Universal carbines drilled and tapped at the factory for the Universal Firearms side mount: 482985, 443733, 308241, 107957, and 33939. All were drilled and tapped to accept the standard Weaver side mount screws that come with the side mount for the carbine.

Installing a new side mount requires the screws be secured with Loctite, preferably red (removable), then removal of the tips of the screws if they protrude into the path of the left bolt lug so they are flush with the inside of the receiver.

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Weaver Installation Instructions (pdf)

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Weaver Side-Mount Scope Base #M Gloss

Model 48409 M
Prior: Model M, Model 08415



https://www.midwayusa.com/product/100921756?pid=376810

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Weaver 1" Detachable Side-Mount Rings Gloss High

Model 49350



http://www.midwayusa.com/product/272671

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Weaver 1" Detachable Side-Mount Rings Long-Style Gloss High

Weaver Model 49340
Prior: Model 09340



http://www.midwayusa.com/product/340963

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As a side note, for a number of years the side mount was made under the Tasco name. The side mount base was catalog no. 804.

Jim

Thanks for that and no issue at all.

The screws supplied with my mount were 8-40, but they didn't fit the receiver. That's why I tapped the receiver to 8-32 and switched to socket head cap screws. Looks like the same major diameter but different pitch. My receiver was neither 32 nor 40 tpi. With such a thin section I was unable to measure the actual pitch of the threads in the receiver. I think I might have guessed they were 8-48 but I have no way to confirm that now since my receiver has already been modified. It would make sense that a finer pitch would have been used considering the thin section of the receiver. More threads, better hold.

I have a late Universal with a weaver side mount installed on my rifle. For me the screws that came with the mount worked fine except a little long and interfered with the bolt. The thing I want to point out is this wasn't designed to use any standard size threads, these screws are what is called resistance screws, they are made to go in very tight because the guns recoil can loosen the screws very easily, I even had to put lock-tite 721 on the threads to keep the screws tight. This is also even more so with the two large take down screws, After only five shots the scope was flopping around and the screws loose, had to use the lock-tite there also. So what I am saying is if the screws turn hard but do go in, then they are correct, if you replace the screws with ones that go in easy you're going to be having a lot of loose scope issues. With the correct screws you can't screw them in by hand and with a screw driver it takes some effort, this is how it is meant to be from weaver.

Thank you Arthur!

Thats a great idea.  Probably soft lead.  What would I insert in the center, presumably to pour the metal around, to serve as the removal core?  Something with flat sides?  It would be really thin.

whoa, jungle carbine with bayo. Did not know they made a bayo!

Well,