Drilling into Chamber wall

[Johnny_Canuck]

Hello all. I have a question today about a swede 96 that I just picked up for a project. It has been drilled and tapped for weaver bases, however, the front most hole is deep... too deep. The reciever and barrel around the chamber have been drilled and tapped for I believe it is a 6-something size as the hole is 0.135 ish inches in diameter. Depth of the hole is .360" from bottom to OD of the receiver. Total measurement from OD of the reciever to the chamber wall is .431". This leaves me .071" chamber wall thickness over this particular hole.

Is it enough for the pressures that the 6.5x55 is going to run?

Likely short term fixes? Am I wrong to assume a screw cut to bottoming length and loctited in would be sufficient?

This is for the most part an academic question as I do have a couple spare m-38 barrels sitting on the shelf and so any and all opinions are welcome. Has anyone seen this before?

 

[Blastattack]

You're not going to blow through .071" of steel in an 1/8" hole. It's perfectly fine as is and I would not worry about it. If the hole was infringing on the chamber, then you have a problem.

 

[cosmic]

Well - Unfortunately the hole appears to go into the meat of the barrel, which is highly stressed with hoop stresses. Over time, the resultant stress concentration may cause a crack to propagate - which would trigger a gas release. However, if the hole is filled with a screw the gas release would be mitigated. I suppose you could find someone to do a fancy finite element anaylsis to determine if the stresses are problematic, but that would cost you thousands.
If you are really concerned, fire a proof round without a screw in the hole, and see what happens.

 

[Ian Robertson]

I bought a used Ruger #1 to build a black powder gun on, 45-70. The barrel on it was not original but looked well done. As I removed the rail I noticed that the GS turned the end of the screws and really did a nice job on installing the rail on the new barrel. And then I noticed that one of the holes had been drilled right through.

 

[sunray]

Like Blastattack says, you're fine. I'd be looking for whoever drilled a .135" hole for a scope mount to give him a smack just on the principle though.

 

[nw mb]

Like Blastattack says, you're fine. I'd be looking for whoever drilled a .135" hole for a scope mount to give him a smack just on the principle though.

...i goofed up on a similar barrel and retired it by welding a plug into it that i can use a 209 primer in to train my retrievers...not gonna chance that...but others may know better than me...

 

[BCRider]

That much metal bridging that small a hole will be fine.

As an example look at the wall thickness for tubing intended to hold very high hydraulic pressure. The smaller sizes use wall thicknesses that seem ridiculously thin yet have burst ratings that are crazy high. As you get up over 1/4 inch bore the walls quickly become far thicker in relation to the bore diameter.

.071 bridging over a 1/8 hole fits into the "small bore and thin wall" situation.

There's other examples of this. My TC Encore barrels are drilled for #6 screws to hold the scope rail down to the barrel. No receiver, just the barrel. I'd have to measure them but the holes almost certainly leave about the same or even less metal bridging at the base of the holes. Yet they come from the factory that way.

 

[Johnny_Canuck]

This is all reaffirming my assumptions that I'd be fine to fire. Had a look at a 72 thou shim for comparison, on a tiny spot that also has brass helping hold pressure I see no issues. Plan is to rebarrel/finish cut the new chamber eventually anyway for the practice. Can always inject some belzona or devcon to fill the hole if I want to re-use that barrel. It also may be close enough to the end that I could set back and recut. Spare parts are easy, spare time is the kicker.