Drilled and tapped barrel

[Jumbopanda]

The Puma 92 that I just bought has a drilled and tapped barrel with a weaver rail base on it. I know that they do offer rifles with this feature from the factory, but I think that on this particular rifle, the base was installed by the previous owner. The holes do seem to be straight, but have some burrs around the edges and it looks like he didn't use a bottoming tap, as the threads end halfway down each hole. The rail base also has an enormous amount of red loctite under it, so much that some of it didn't even dry. It looks like he used the loctite to bed the base to the barrel, since the tapered round barrel didn't fully contact the base evenly. Is this a commonly used technique or just a hack job? And is it necessary to have a base that rests perfectly on the barrel? The whole thing looks rather sloppy, although I will admit that after two range trips, the base did not loosen. But today I took the base off and then tried to put it back on, only to find that I stripped one of the screws while trying to tighten it, because I was pushing it down into the unthreaded portion of the hole. The threads in the barrel do not seem to be damaged, but the screw is useless now. I think I will get a bottoming tap and clean up these holes a bit before I re-mount the rail.

I am curious to know how deep one is allowed to drill when drilling and tapping barrels. This barrel is about 0.875" in diameter at the point where one of the holes is drilled, and the hole is 0.18" deep, making the barrel 0.03" thick at its thinnest point at the very bottom of the hole. Would this potentially cause any problems, especially for a high pressure round like .454? :veryconfu

[fecmech]

The newer Braztech 92's come from the factory D&T'd for a mount. The correct part number for the Rossi mount is P892 and that is the one you need because it is made with a taper in the base to compensate for the barrel taper. The base you have may be an earlier base used on the singleshots and Contenders which has the same hole pattern but no taper. If that base is not shimmed at one end you will more than likely run out of elevation on your scope before getting a correct zero.

[JZdryfly]

I had a base made up by a machinist and had 4 holes drilled 4 threads deep. Used some shim stock to compensate for barrel taper difference with base taper. Then replaced the shim with JB weld. It's nice and tight and level. Now with a scope I'm getting 1.5" groups at 200 yards from my Casull with Lymans bullet. It really wallops metal targets

[S.R.Custom]

...I am curious to know how deep one is allowed to drill when drilling and tapping barrels. This barrel is about 0.875" in diameter at the point where one of the holes is drilled, and the hole is 0.18" deep, making the barrel 0.03" thick at its thinnest point at the very bottom of the hole. Would this potentially cause any problems, especially for a high pressure round like .454? :veryconfu

Depends. How far forward of the chamber is the hole? Any closer than 3" to the chamber would make me nervous.

For reference, the typical timing notch cut over the chamber of a Ruger Super Blackhawk is only .050"-055" thick. And that's over the chamber.