Scope ring torque?

[harrym]

When I went to the range today, my AR15's scope was loose in its Burris PEPR mount. I had shot less than 50 rounds since mounting the scope. I noticed that the reticle was off vertical, so that's when I checked it. The only thing besides shooting it that could have changed is replacing the stock handguard with a new MOE-SL handguard. Anyway, it's lined up now and the 12 screws are torqued at 12 pounds. What should the torque be for a scope in this mount? I considered using some blue Loctite, but I'm not sure I'll keep this scope on this rifle.

 

[cyphertext]

Taken from Burris web page...

Scopes - rifle scopes, handgun scopes, hunting scopes by Burris Optics

Q. How do I know how much to tighten my rings and bases?
A. Use the following specifications to correctly tighten your rings and bases. Be careful not to over tighten as doing so can damage your product.

Eliminator / LRFP Base Clamps: 40 inch-pounds
Signature / Zee Ring Tops: 20 inch-pounds
Signature / Zee Base Screws: 30 inch-pounds
Rear Windage Base Screws: 40 inch-pounds
AR-P.E.P.R. /Tactical Ring Tops: 20 inch-pounds
AR-P.E.P.R. /Tactical Ring Crossbolt: 65 inch-pounds
Signature Ring Clamps: 30 inch-pounds
Rimfire / Airgun Rings: 20 inch-pounds

 

[MichiganScott]

Lock-Tite can make a real mess of the small screws used on the rings. If you really feel that they need help, use some anti-seize compound on the screws. Not only does it make it easier to remove them when you need to, it helps keep them from backing out if torqued to spec.

 

[78Staff]

Echoing what has already been said, different manufacturers require different specs - Larue is 30in-lbs, for instance. 12 is pretty low. Either way, loctite should not be required for ring screws if torque specs and proper tightening procedure is followed.

 

[harrym]

OK, I retightened the ring top screws to 20 pounds. I'll see if they hold at that torque. I had to take a rifle to a gunsmith once to remove a scope base that had been sealed with Loctite, so I want to avoid that. Thanks for the Burris chart.

 

[Rastoff]

If you really feel that they need help, use some anti-seize compound on the screws. Not only does it make it easier to remove them when you need to, it helps keep them from backing out if torqued to spec.

Please, please don't do this. The reason they won't back out with this method is that you've greatly over torqued the screws.

Anti-seize is a kind of lubricant. Unless the manufacturer specifically states to use anti-seize, the torque values are for dry screws/bolts.

Torque is a measure of twisting force. The friction created by the increased surface area of a screw is a factor in determining the correct torque value. Because anti-seize reduces the amount of friction, the actual force applied by the screw, when tightened to the recommended torque, is greatly increased.
I have seen wheel lugs snapped off before the recommended torque value was reached because anti-seize was put on the lugs.

So, don't use anti-seize on bolts or screws or nuts when torquing to the manufacturer's spec.


Now, to keep your scope tight, but not over tight, try this....

Mount the scope and go through the pain staking process of getting the reticle level. Then head to the range and fire two shots.
Check the scope ring screws.
Fire 5 shots.
Check the scope ring screws again.
Fire 10 shots.
Check the ring screws again, but they should be good by now.

Doing this helps settle the parts. Any movement that was going to happen, has happened. By doing it incrementally like this, you get it tight before the scope can move out of place. So, do this first, then zero the scope. If you have a quality scope and quality rings, it will stay zeroed for years to come.

 

[MichiganScott]

Please, please don't do this. The reason they won't back out with this method is that you've greatly over torqued the screws.

Anti-seize is a kind of lubricant. Unless the manufacturer specifically states to use anti-seize, the torque values are for dry screws/bolts.

Torque is a measure of twisting force. The friction created by the increased surface area of a screw is a factor in determining the correct torque value. Because anti-seize reduces the amount of friction, the actual force applied by the screw, when tightened to the recommended torque, is greatly increased.
I have seen wheel lugs snapped off before the recommended torque value was reached because anti-seize was put on the lugs.

So, don't use anti-seize on bolts or screws or nuts when torquing to the manufacturer's spec.


Now, to keep your scope tight, but not over tight, try this....

Mount the scope and go through the pain staking process of getting the reticle level. Then head to the range and fire two shots.
Check the scope ring screws.
Fire 5 shots.
Check the scope ring screws again.
Fire 10 shots.
Check the ring screws again, but they should be good by now.

Doing this helps settle the parts. Any movement that was going to happen, has happened. By doing it incrementally like this, you get it tight before the scope can move out of place. So, do this first, then zero the scope. If you have a quality scope and quality rings, it will stay zeroed for years to come.

We will have to agree to disagree on this. Leupold strongly recommends using oil on the screws for their rings and bases. There is a big difference between torquing down a new ring or base screw to 15-65 in-lbs than when torquing a rusted lug bolt to 100+ ft-lbs.

By the way, modern oils creep into just about any place. You will eventually end up with oil on the threads anyway. I've never torqued off a screw head since I started using antiseize, something I can't say for my friends that insist on using Lock-tite.

 

[Rastoff]

We will have to agree to disagree on this.

OK.

Leupold strongly recommends using oil on the screws for their rings and bases.

If the manufacturer recommends it, then they've already taken the added torque into account. So, in that case I'd say it was not only OK, but necessary.

 

[SoCoRuss]

Does the torque recommended have leeway. I have the Leupold Patrol. Guide says 20 inch lbs. I have multiple inch lbs torque wrenches but they all start at 25inch lbs! Not real happy to have to get a new one for 5 inch lbs difference.

 

[cyphertext]

Does the torque recommended have leeway. I have the Leupold Patrol. Guide says 20 inch lbs. I have multiple inch lbs torque wrenches but they all start at 25inch lbs! Not real happy to have to get a new one for 5 inch lbs difference.

Leupold says 18 - 22 inch pounds. When I worked at Academy mounting scopes, we didn't have torque wrenches. Got them good and snug and then went about a quarter turn more.

Leupold also recommends lightly lubricating the screws...

 

[Rastoff]

Does the torque recommended have leeway. I have the Leupold Patrol. Guide says 20 inch lbs. I have multiple inch lbs torque wrenches but they all start at 25inch lbs! Not real happy to have to get a new one for 5 inch lbs difference.

The best click type torque wrenches on the market have a tolerance of +/-10% which means 22.5-27.5inch/lbs for your wrench. If it hasn't been calibrated in over a year, chances are that tolerance has gone to 20% or worse. That means the torque value could be anywhere from 20-30inch/lbs.

Now, we're talking about inch/lbs here. That's not really a lot of torque. I seriously doubt that you'll damage the rings, screws or scope at that torque.

Just for the record, I have been a Metrologist for about 30 years now. I have calibrated thousands of torque wrenches in that time. The majority of them, that were more than a year old, were either limited to +/-20% or thrown away because they were worse than that.