When drilling and tapping a shotgun barrel for rifle sights, can the hole for the rear sight be drilled through the barrel entirely like the front bead's mounting hole? If yes, is this also permissible in the chamber area?
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November 5, 2010, 04:30 PM
Front sight yes.
Rear sight NO.
Chamber pressure is concentrated right where the holes would be.
You might want to consider putting a higher front sight on and drilling and tapping the rear of the receiver for the rear sight.
It is a non-stressed part on most modern shotguns with a barrel extension for the bolt to lock into.
That will give you a much longer sight radius and potentially better accuracy.
November 5, 2010, 04:41 PM
In this case the shotgun is a Marlin model 55 and installing the sight there would be troublesome as the bolt locks on the handle so there isn't a solid rear area of the receiver bridge.
Just for kicks I temporarily mounted the sights with an adhesive material to test the concept. The rear sight was in front of the chamber by a few inches, and the front ramp was touching the bead. Even with the rear sight adjusting all the way down the POI was still 12 inches low at 25 yards. Seeing as how the chamber diameter is larger than the rest of the barrel I surmised that this might be enough to get the poa to = the poi
Can the rear sight be drilled and tapped say 2.5 inches in front of the chamber area?
Doing this in conjunction with a taller front blade ought to do the trick
I suppose there's always JB Weld too in case bubba shows up
November 5, 2010, 05:06 PM
the first 12" or so in front of the barrel receive the brunt of the pressure.
Lock-Tight makes an adhesive called #380 Black-Max that is used to adhere vent ribs to barrels.
Properly used on a de-greased barrel & sight base, I think it would hold simple sights on till the cows come home.