Re: Couple questions about adjustable McMillan stocks
First, let me say that we will fix this for you if you like. Standard warrentee procedure, you send it in to us and we fix it for free and pay the freight back.
Second, let me tell you how we figured out the problem and fixed it. Originally the thumbwheel adjuster was designed for the people using iron sight competition guns that needed very fine cheekpiece adjustments at every range change as they moved their micrometer rear sights up and down. These guns were heavy guns usually in .308 and .223 and we never had any problems.
To install them we drilled two undersized holes in the stock and glued and screwed two little pot metal threaded anchors into the stock and the thumbwheel block was attached to these anchors with two screws.
Then a couple of years ago people started having problems with them shooting loose, usually the metal anchors were working loose in the stock and then the screws would work loose. For a while we fixed them by re-gluing the anchors in, usually worked OK except sometimes it would happen again. Soon we were all getting frustrated with this so I took another look at the system. Set on on my desk and just stared at it for a couple of days trying to figure out "why". Used some x-ray vision (?) and mentally put some strain guages and accelerometers here and there and tried to understand what was happening. Finally it dawned on me. The thumbwheel block, wheel and cheekpiece has mass, and the recoil of the shot has to get it moving backwards with the rest of the rifle. And all the thrust of the recoil was 100% on those two little anchors under the thumbwheel block. If the rifle has a muzzlebrake on it then when the gases hit the vanes on the brake all the thrust to stop the recoil was again applied just to those two anchors. This back and forth force pushing on these two anchors was slowly crushing the softer lighter fill we use in the butts for weight distribution and the anchors were working loose. Bingo, now we know how to fix the problem. First, we put the anchors in a different wsy, we drill the holes oversize so the threads don's crush any of the soft fill as they screw in, fill the hole with activated epoxy resin, put a little piece of tape over the hole in the bottom of the anchor and sit them in place until the epoxy has cured. Now the anchors are in a solid cylinder of very hard resin. Now the main problem, there is a little gap between the front of the thumbwheel block and the front and back of the stock. I think this was just for ease of assembly so we changed the inletting to let the front of the block touch against the main buttstock. Now we put a dab of marine tex here and push the block forward to firm contact and screw it down. Then we fill the gap behind the block with a thick epoxy putty. Now the block itself is tight against both the front of the stock and the back of the stock and the forces to get it moving back and forth under recoil is applied directly to the block and not just to the two little screws and anchors.
We have been installing them this way for over a year now and have ( to the best of my knowledge) never had even one work loose. If you want to fix your own it's simple, take the thumbwheel block out of the stock and check the anchors. If they seem a bit loose just screw them out and reglue them into place.
Now get some of that epoxy putty paste at your local hardware store, the kind that comes in a little light gray strip and a dark gray strip, mix them together well and fill the gap at the front of the block and rear of the block solid with this putty.
Don't use a liquid type and pour it in as it will run under the block and down into the cheekpiece post holes. This seems to be a final permanant fix and they will not work loose again.
Again, we will be happy to fix these older installations for free if you will get them to us.
Sorry about the long post.
Dick at McMillans
