How tight to torque when installing a scope mount on an M1A?

[Red State]

Can anybody help me?

I am installing an ARMS scope mount on an M1A, but I don't have the wrench that measures inch-lbs.

How tight should I torque the bolt into the side of the receiver? The instructions recommend about 90 in-lbs.

Would that be similar to twisiting really hard with a screw driver?
Or would it be finger tight with a 6" wrench or an 8" ratchet?

I will be using loctite, so I have a margin of error and I just need to be in the ballpark with this.

 

[Cousin]

I just snug my ARMS-18 down with some loctite#4. Be firm with a nice even pressure until snug . 90 ft/lbs shouldn't need to much beef.

 

[Sport45]

Cousin,

Welcome to The High Road!

(It's never too late to edit. )

 

[Al Thompson]

RS, I have a Warne inch pound tool and, IIRC, it's set for 30 inch pounds. I was surprised at how little pressure that took. So, IMHO, good and tight with a screw driver would be much better than really cranking on it and possibly stripping something out.

Hopefully someone with more experience can chime in and set us straight.

 

[Cousin]

Thanks for the welcome, and the correction Sport45. Yikes!

Well nothing like a good first impression.

 

[Art Eatman]

Back before Allen screws and suchlike became common, "good and snug" with a screwdriver worked just fine for me. And we didn't have Loctite, either.

90 inch-pounds? 7.5 foot-pounds. Not all that much. Avoid the "tighten until it gives and then back off a quarter-turn" thing.

 

[Red State]

Thank you all.

I do like hearing from people who know what they are talking about.

Nice and snug with a screwdriver is the plan.

 

[Ryder]

I don't bother to measure torque on small items. I just snug it and then add 1/8 turn or so to give the threads some bite.

I don't know what you consider "finger tight" but according to what I've witnessed most guys maximum grip strength measures out to 100lbs +/- 10lbs (a few of us can get up to 120 ). Have to be careful not to over tighten. If something works loose you can always re-tighten.

I habitually check for looseness out of habit (lots of vibration on a motorcycle) but it's not a common problem for most things. I rarely find anything loose on my guns except as they come from the factory.

 

[madcratebuilder]

I don't know what you consider "finger tight" but according to what I've witnessed most guys maximum grip strength measures out to 100lbs +/- 10lbs (a few of us can get up to 120 ). Have to be careful not to over tighten. If something works loose you can always re-tighten.

I think people are confusing INCH pounds with foot pounds. It takes the average man a three foot bar to tighten a bolt to 100 ftlbs of torque.

90 inlbs is not very much, single hand, screwdriver handle tight. If you do not have experience with a torque wrench you have no idea of what these torque values feel like. You should buy a cheap inch-lb beam style torque wrench and become familiar with them.

 

[Tirod]

Grip strength isn't torquing a bolt. My last physical when working on a Amada 100 ton press brake showed I had 134# of grip. With a typical Craftsman click torque wrench, I can peg it working on head bolts, etc. VW crankshaft nuts are torqued to 240 ft pds, which is off the scale. They take a cheater bar to remove.

I have a inch pound torque wrench, and it's basically useless. Most mechanics can easily break a 3/8" clutch or torque converter bolt with a closed end wrench, and they get only 38 - 45 pounds max.

What is interesting is a recent article (American Rifleman?) that showed most scope rings and mounts are overtorqued to the point of damage. Even gunsmiths have been found to have warped tubes and stripped threads following the advice of some old wive's tale to tighten them as far as humanly possible. The resulting torque values were found to be double or triple needed.

Use blue loctite and get them firm, it'll do. Use red, you will have to boil the parts to get them loose. Always consider what went together may later have to come apart. If it's that critical, stake it or tack weld it.

 

[Art Eatman]

Ah, yes: "Rip, rap, ream, rotate and weld shut for free-running press fit."

 

[Red State]

Thanks all for your help. With firm pressure and a little blue loctite on all screws, the mount now seems to be securely mounted. I hope I don't have to remove this baby for a long, long time.

Tomorrow is one last range trip with the open sights to make sure that the mount does not give me any ejection/extraction issues before I proceed with the rings and scope.