Home Forums Hunting & Shooting Hunting Optics Base contact

Did this one yesterday and it's a good example why epoxy bedding the scope bases to match the receiver is beneficial.

The contact pattern clearly shows how little of the base(s) actually contact the receiver. Only portions of the machined finish of the bases around the screw holes show any contact at all:





A dab of Pro Bed last evening and popped them off this morning. After a bit of cleanup and radiusing the screw holes, they'll go back on with near 100% contact:



Good shootin' -Al

Al,

Can you lap the bases to avoid using epoxy? I've never tried to lap bases.

Swede65

Use a strip of 3M Vinyl electrical tape... same as the rings.

Bed, torque, wait an hour, torque.

Like painting them on, except that they come right off when the screws are removed.

Also grease the screws, same as the cap screws.




GR

Al;
Top of the morning to you sir, I hope that this last Friday of August is behaving for you down in Lower Dakota and you're well.

Thanks for the very clear photos which show the differences in the radiuses, I appreciate you taking the time to do so.

It's for sure something that I've been aware of for awhile now and it shows it better than I've been able to explain it to anyone.

Thanks again and all the best.

Dwayne

Just to make certain that I'm reading your process the right way: You use a piece of electrical tape between the bases and action and between the scope and rings?

Sometime back I bought a rig to use as a donor action. A previous owner presumably used electrical tape between the rings and scope. Was .5" gooey marks by each ring where the scope had been slipping through the years. Was a 270 with a 4x Leupold, which are very light as far as scopes go, so can't imagine that the rig was putting out that much recoil force to move the scope.

Anyway, I'd imagine that putting tape under the base would still leave a level of movement as the tape will never set up and get hard. Maybe it thins out enough when torqued down that it is stiffer than I'd think?

The way Al does it is fantastic, and I've used that method myself through the years when the base contact has been less than Ideal. I first usually try to find a set of bases that fits better, but you have to do what you have to do to get the bases on there solid so as not to place addition stresses on the scope.

One other thing about Al's method is that it helps keep moisture and oil from getting in-between the base-action. Even when things fit up really tight, I put a film of thread locker or nail polish between the base and action to keep any water or gun oil from getting down in there. I also thread lock all screws both to keep moisture and oil from getting down in the threads, and because screws on a rifle getting tighter hasn't ever happened to me, but the inverse has.

Looks good but I’m not convinced the unmodified base was hurting anything. I’ve never had a base move on me.

Have you followed the instructions provided?

No slip/slide, holds zero, and shoots sub-MOA.

.270 Win and 9.3x62mm.

The .270 Win on several rifles over decades of shooting.


For the rings - cut the tape back ~ 15° at each end, leaving base and cap centered 150° arcs.

This will keep the scope from binding when mounting or removing.

So ya know.




GR

I've haven't lapped any bases as epoxying bedding them corrects all the issues.

Good shootin' -Al

You'd be surprised how much poor contacting base will move and flex during a shot even when they appear to be tight. Increasing the contact surface by bedding the bases spreads the load out over a much larger area which increases the stability of the mounting system...giving you not only better consistency but a system that will better withstand hard knocks, falls, etc.

Good shootin' -Al

I just put very thin layer of Blue Loctight then install. When I say thin I mean you do not even see blue they just look wet. Has always worked for Me.

A great way to see this is simply shine bright light into the front of a base while from the rear of the base looking between that base and receiver to see how much light comes through. Doing this on few of my rifles was eye opening on a few of my rifles, and almost blinding on a couple.

I think you are trying to create a problem Where there is none. I will be 65 soon and have mounted hundreds of scopes in my day and never had a problem with bases that were made for the gun.

I just glue them down with epoxy, in the screw holes too

What problems are created when the bases and the receiver fit perfectly? -Al

Machined in pic rails.....problem solved!! I won't use an action if it doesn't have'em.....

I bedded a rail on my wife’s M7 because it didn’t lay perfectly flat. It’s a thing with certain brands. Some people don’t check for it or notice it.

I’m pretty certain without knowing either of you that what is good enough for you may not be good enough for the man sharing his experience in this thread. No offense intended.

I’m not able/willing to take advantage of all the wisdom shared in these threads but I appreciate it.

💯💯💯


I pay close attention to (and appreciate) the fellers that are particularly fastidious.

The fascinating part for me are the guys that generally take exception seem to be the ones that never leave their locale or shoot game past 75 yards not comprehending that things might be a little different beyond their backyard.

This, this, and this... WTH?

You should try 1/4” lag screws next time.