Installing flush-mount sling swivel cups

Today I’m going to install three flush-mount sling swivel cups in a Bell &
Carlson stock for my Remington 700. Three because I want to use a Ching sling
with this rifle and flush cups because I’d like a smooth surface when shooting
over any kind of rest.

I have quite a bit of work planned for this stock, but we’ll start simply.
The sling swivels I purchased are Grovtec threaded cups, made right here in Oregon.
They install with a 9/16-18 tap, so I bought a cheap, carbon steel tap as
well.

Additionally, a little Devcon Steel Putty, some mixing sticks and we’re ready
to go.
Sling installation materials

I want the third sling attachment point pretty close to the middle of the
rifle, so just forward of the bottom metal it is. BUT, that puts it right in
line with the recess for the recoil lug. I inserted a gauge block into the
recoil lug and measured across that to the bottom of the stock. Subtracting
the length of the gauge block from the measurement I see that I have about
0.612″ to work with. I only need to drill 0.562″ for the swivel installs, so
everything will work out.

measuring recoil lug recess

I put the stock in the mill vise. Note the 1/2″ thick felt pads used to hold
the stock. These not only pad the stock against damage, but grip very well.
I located the front hole from the factory swivel and dialed it in. I then
inerted a transfer punch in the hole and visually checked vertical from the
front and side. The square in the photo helped provide a reference.
aligning front sling hole

I centered the spindle over the existing hole and gave it a quick
verification.
verifying hole position

Since we’ll ultimately apply epoxy, I degreased the tools and swivel cups with
acetone before proceeding.
degreased tools and parts

The material cuts surprisingly well and the first hole is done.
front hole drilled

While in the same setup, using the spindle for alignment, I tapped the hole.
Tapping setup

Finally, a test fit to make sure the cup threads in and will go flush. No
problems here!
Test fit of first sling cup

For the middle cup, I used a level to position the stock and stayed on the
same center line previously established.
Leveling stock for middle swivel

Repeat the same procedures, being careful not to exceed the previously
determined safe depth and that’s two down.
test fit of middle swivel

Removing the factory rear stud, you can see that the pilot hole is
perpendicular to the angled part of the stock.
angle of factory installed rear stud

Again, I used the level to set up the stock.
positioning the stock for the rear swivel

That last hole didn’t feel as good, there wasn’t as much substantial material
there as in the other two holes. The tap felt loose too. I’d do things a
little differently if I were going to do it again. I’ll cover changes at the
end of the article.

The cups have a hex hole in the bottom to let you use an allen wrench to drive
them in. I greased mine up with some paste wax to keep the epoxy from
sticking to it. Just rub on, let dry and wipe off.
release agent applied to wrenchNext I mixed up the epoxy. These crummy two-tube things have never worked
well for me as the hardener and the epoxy are different viscosities, so they
don’t really dispense evenly. To get a good mix dump the entire contents of
both and mix. (I didn’t, but I would next time…)

I threw a little epoxy down each hole, then smeared the threads liberally and
screwed the cups in.
swivel cups insertedAbout four hours later I came back with some ‘Goo Gone’ and cleaning patches
on popsicle sticks and cleaned away the excess epoxy.
cleaning off excess epoxy

24 hours later, after some tussling, the swivels are installed.
Installed sling swivels

I had a couple of problems however. First, I had turned one of the cups below flush. Enough so that the swivel wouldn’t snap in place. After beating my head
against it a bit, I finally tried backing the cup out, via the threads. To my
surprise and amazement, it worked. That wasn’t entirely good news as I had
expected the epoxy to hold onto the cup better than that. I have no way of
knowing for sure, but there are a couple of things that might have gone wrong:

1. The epoxy may not have had enough hardener. As mentioned above, I couldn’t
get the materials to dispense in even quantities. In hindsight, if I’m using
these syringe packs, I’ll dump and mix the whole thing. A bit of a waste, but
better safe than sorry. Better yet, just open the big tub, I have one for the
bedding work I’ll be doing later.

2. The threads may have thwarted my degreasing. I degreased by wiping with a
shop towel and acetone. It’s conceivable that some oil remained in the root
of the threads and prevented adhesion. Next time, either dip or maybe bead
blast.

3. The Goo Gone could have crept into the junction. I don’t really believe
this, but some people won’t use solvents to remove epoxy overflow when bedding
due to concerns that it will migrate. Again, I don’t think this happened, but
it’s something to consider. In hindsight perhaps I’d mask the area around
each hole and just peel the masking off rather than use solvent.

In any case, after backing the cup out enough to attach the sling swivel it
appears to be holding fine, so I’ll leave things as they are.

That’s it for now. The next time we look at this stock, we’ll enhance the
inletting a little to fit some steel bottom metal.

GsT

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