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Drilling and Tapping Rem 721 rear receiver ring

rob daniel

Hot Rolled
Joined
Apr 27, 2005
Location
Southern California
I have an early 721 with no scope mount holes in the rear receiver ring. I plan on using 8-32 or 8-40 screws. Any idea how hard the action is? Carbide drill or end mill for the holes? Will a new standard quality OSG tap cut well?
Thanks,
Rob Daniel
 
I have an early 721 with no scope mount holes in the rear receiver ring. I plan on using 8-32 or 8-40 screws. Any idea how hard the action is? Carbide drill or end mill for the holes? Will a new standard quality OSG tap cut well?
Thanks,
Rob Daniel

Use a 8-40 tap not a 8-32. The receivers run around 38 Rc and you will not have any problem drilling & tapping.
 
8-40 is a standard gun thread and sight base screws with a Weaver head or cheese head ( depending on the base ) are readily available. The 8-32 screws found at your local hardware will not fit the base screw recess because the head dia. and/or the countersink angle is not standard.

RWO
 
The finer pitch 6-48/8-40 special scope and sight mount screws, put more threads in a thin section than the standard fine pitch screws...

Finer pitch also has a slightly thicker cross section, which helps in shear.. Which scope mounts are exposed to during recoil..

If receiver was so hard you had to drill it with carbide, you would not be tapping holes.. Spot annealing required.

Really if you have never done this, send it to a competent local gunsmith. Nothing like drilling a scope mount screw hole, right through upper bolt locking lug shoulder...

Buy the time you buy the special taps (both plug and bottoming), you are approaching what it costs to have it done..

OSG web page flakey, did not see any 6-48 or 8-40 UNEF taps...
 
Really if you have never done this, send it to a competent local gunsmith....

This.

Just an FYI,the "rear receiver ring" is called the bridge, the front where the barrel screws in is the ring. Are there any holes in the receiver now, either in the ring or bridge? If so, what size are they? There might be two holes on the left side of the bridge for a sight base.
 
The action is taped 6-48 in the ring and has no holes in the top of the bridge. There are two 6-48 tapped holes on the side of the bridge as if for the period Lyman 48 peep sight.
I have fitted and chambered several barrels for benchrest shooting and have built a few custom rifles but have never had to drill a Remington action. My questions might seem odd but I have no experience with drilling and taping a Remington action. I have experience drilling and tapping 4130 pre hard and 17-4.
Thanks for your input,
Rob Daniel
 
They drill and tap quite easily. No need for special cutters. Just continue the 6-48 holes centered on top of the bridge. The factory hole spacing on the bridge is .605". Not sure what the spacing is from the rear ring hole for the 721 (long action), short action is 3.630" from the rear ring hole to front bridge hole. Measure a one piece mount. I know a lot of folks are going to scream bloody murder that they are .600", but .605" is what the print says.
 
To make this match up with commercially available bases, use the base you choose as a layout check before you drill. I think on those actions there is a cut out as if you could use a stripper clip to load the rifle, and that notch may limit whether you can have one hole or two at the rear. It will machine easily and definitely match the 6X48 holes already in the action.
 
I finally tapped the receiver/made a jig to hold the receiver and locate the holes. The 721 was easy to drill but did not like the taps. I used 2 taps from JGS, the reamer people, but the tapping was difficult. If I have to do something like this again I will source better taps.
 








 
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