Gunsmithing Questions on installing flush cups

[Sendit6.5]

I'm getting ready to install some McMillan flush cups in a Savage Accustock and a HS Precision on Sendero. I've never done it before but it seems pretty straight forward and easy. I have the proper drill bit (and a depth stop) and tap and some marine tex. I'll just be using a cordless drill as I don't have machine shop tools.

Questions:

1. Can I just unscrew the existing sling studs on the Accustock and then drill and tap the holes to accept the flush cups; or, do I need to find new locations?

2. I'd like to install a couple of cups on the side of both stocks. Is there any problem with doing this on the butt on the Accustock? Just wondering if there's enough material to secure the cup? I'd like put it about 1.5" from the end of the stock material and about centered, height-wise.

3. Anything I can do to eliminate or minimize splintering or cracking of the stock material as I drill?

Any advise you can share?


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[LRI]

Ever poke a hole into a piece of sheetmetal with a big drill? Goes great for about 20 seconds then the edge of the drill grabs and the material gets pushed out of the way instead of cut. The drill basically takes on the behavior of a tap after that. Your wrist will tell you real quick that it wasn't the best solution. Composite stocks are "hard boiled eggs" and behave like this to some degree. The shell is what you have to get past, the core is pretty easy. The rub is drills don't do a good job on composites. X2 when using a hand drill... A 9/16-18 pitch flush cup calls for a .512" drill size if I recall correctly. I just use a half inch tool as the added bite on the threads is never a bad thing.

The rub however is I have a rigid setup in a mill when doing this. I use an endmill to plunge the hole. Even with my resources here I'd never try this with a conventional twist drill. It will likely grenade the shell material on the stock. If you are hell bent to do this at home, I'd consider a spade bit or some kind of coring drill instead. Much safer in terms of not tearing up the stock. Know that once you get through the shell its going to start eating very quickly. You could very easily end up on the opposite side of the stock before you know it.

Next, I don't know much about Savage stuff. One thing I will caution you on though is the core material used by some companies. HS and others use a poly foam resin to core a stock. It's a two part mix that goes "crazy exothermic" and swells like bread dough. It's light, it's strong enough, but when you attempt to install peripheral features to it, you find out real quick that it sucks. Flush cups fall into this. It does not stand up well to metal objects being stuffed into it. The material surrounding the threads just breaks down and your work falls out of the stock, or comes loose and now it flops around inside of it. (which really sucks btw)

It would be worth your time to sort that out first.

Good luck and hope this helps.

C.

 

[WarbirdWeaponry]

Do a search for Blair Rotabroach. They are spendy but work great on thin sheet metal and carbon fiber shells.

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