Monthly Archives: June 2014

Scope Mount Screw Torque?

Scope Mounting Screw Torque

This is a hot topic today. I will give you what I have learned over the past 30 years of doing this for a living. It is not all that hard, the screws need to be tightened, not over tightened, enough so the mount is not loose and the screws will not loosen up. I do use thread lock on ALL scope mount and ring screws. I use small screw, service removable thread locker. It is generally pink or a milky red or purple in color. Please see my Thread Locker post for more details.

Here are the most important things to remember when torquing screws.

We use screws made in the USA. Purchase only ALLEN® brand Allen wrenches. Inferior brand wrenches fit loose in the screws and will lead to rounding out the head.

When you insert the wrench into the screw head make sure it bottoms out. If you only insert the wrench in say half way, that will also lead to rounding out the head. We see screw heads rounded out and upon examination with a 20X magnifying glass it is obvious most of the time the wrench was only inserted part way.

When torquing screws with a Torque wrench to a particular specification there are many variables. I have looked over at lest 20 torque specification charts and even most of them don’t agree on specs. There are also different specifications for dry or lubricated screws. For our purposes we are going to consider the thread locker on the screw to be a lubricant. Here are the specs we suggest using.

6-32 9 inch pounds
6-40 11 inch pounds
6-48 13 inch pounds
8-32 18 inch pounds
8-36 20 inch pounds
8-40 22 inch pounds

I know this can all be debated until the cows come home but you can’t go to far wrong using the above specifications. I suggest checking the torque after your first trip to the range. If you have done everything correctly all the screws should be set at the same torque you originally applied.

Old School
Many of you know I am an old timer. I have been using the following method of tightening scope mount screws since I started in business. I can say I have never had a failure using this method.

Using a short arm ALLEN® wrench I snug the screws down. We all know what snug is. I use one finger at the tip of the wrench and tighten it lightly. I then turn the wrench another 1/8 of a turn. We did an experiment at the shop and found that is pretty consistently 20 inch pounds of torque with me doing it. I am sure it varies with different people tightening the screws but it should get you pretty close.

All in all I don’t believe it is anything to get uptight about. It is pretty straight forward. Torque wrenches are great and provide consistency but I don’t believe you can’t mount a scope mount without one. It has been being done for over 100 year without Torque wrenches with great success.

Using Thread Locker

Using Thread Locker on Scope Mounting Screws,

Thread locker should be used on ALL scope mount attaching screws. Screws not thread locked will come loose eventually.

I know many of you already know how to use thread locker but for those of you that do not, please read carefully.

We will discuss small screws such as #6 and #8 screws. Generally scope mounts and items like that use these size screws for mounting. Much of this applies to most any size screw.

The enemy of thread locker is oil. Any oil on the screw or in the threaded hole decreases the strength of the thread locker. It interferes with the curing of the locker and decreases it’s strength. I use simple carburetor cleaner on both the screw and the threaded hole. I squirt both surfaces with the carb cleaner and then compressed air dry each. When the surface is clean it will look dull. Shiny generally means oily.

For the size screws we are talking about I use small screw thread locker. It can also be called service removable. It is generally blue or a sort of pink in color. You can use the permanent red thread locker if you like but it is a little more difficult to remove the screw afterwords.

To remove a small screw that has been permanent thread locked (Red) just apply heat to the screw itself. I generally do this with a soldering iron or a small butane torch. Apply the heat slowly so you don’t discolor the item being held by the screw. Here is the trick. As you apply heat you will smell a sweet aroma, that is when the thread locker has been melted and is ready for removal. Remove the screw as quickly as possible so the locker does not try to bond again.

Back to our applying thread locker to a small screw. I apply a small amount to the screw then the threaded hole. Taking just the screw, I run it in and out of the threaded hole to get the thread locker evenly distributed between the threads of the screw and the threads in the hole. You are now ready to mount whatever it is that you are trying to mount.

Generally thread locker drys in an hour or so. If it has not dried in that time period it is possible that the surfaces were not cleaned sufficiently and you would need to repeat the above process.

Always check to be sure you have not dripped thread locker into your receiver, barrel or other such places, it can cause huge problems. You can use carb cleaner to wash off excess thread locker.

We offer Thread Locker on every one of our scope mount application pages. Click teh following link and select your firearm from the list. You will find a shopping cart button for thread locker.

Scope Mount Fitment Problems

The biggest reason scope mounts have mounting issues are the places we choose to mount them on the firearm. We can all agree that no one likes to drill and tap their firearms? Sometimes there is no other choice but to do so but we would all rather not. As a designer, to design a no drill and tap mount, I have to pick a place or places to attach the mount to existing features on the firearm. That can consist of front sight slots, rear sight slots, existing tapped holes and so on. Here is where the problem comes in. When the manufacturer machines whatever holes or slots into your firearm they generally do not do it with the intention of us mounting something on them. They keep the tolerances they need to make the part they are attaching work, not our scope mount. Let me give an example.

RUGER® GP-100 rear sight elevation screw hole. We use that for mounting the rear portion of our mount to that particular revolver. RUGER® uses that hole strictly to mount the rear sight using the elevation screw. For their application the screw hole can move a little forward or backward and the hole still works for their purposes. We would love to have the hole in the same place all of the time but it is not there for our use. We have to design around these types of things all of the time. When we manufacture a new scope mount we will run a small batch and sell them to customers. If we get feedback from customers having problems we document it and adjust accordingly. We may have to elongate a hole or move it forward or backwards to get it to a sweet spot where it fits all applications. We document most all customer input and fine tune our dimensions until we no longer get calls about the mount having fitment issues.

This is not an excuse it is just a little explanation of why things don’t fit just perfectly all the time. We can hold +-.001 dimensionally all day but you have to come up with the sweet spot first to get the machined feature in the correct position. We strive every day to design and manufacture the best parts available. We run small lots and do regular inspections on all of our parts to keep quality superior.

Welcome to our Scope Mounting Blog

Welcome. Weigand Combat Handguns Inc and WEIG-A-TINNY® have opened this blog to aid anyone trying to mount a scope mount for the first time. Even for the seasoned user there may be usable information here for the taking. We began scope mount production in 1986 and that gives us years of valuable experience that we can pass along to help you have a more enjoyable experience mounting your optic. There is nothing more frustrating to a shooter than having an optic come loose and loose zero. We all spend time and expend expensive ammunition zeroing our firearms. With a properly mounted scope mount your zero should stay put for years to come. Hopefully you will find the information you need to install your optic and also have an enjoyable time doing so.

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