Barrel thickness under front dovetail--safety check

[Cosmoline]

I recently cut a front dovetail leaving .050" of solid barrel at the thinnest spot out of a 1.5" thick barrel wall. My understanding is that this thickness is standard for a front sight, and I was using a standard front sight. I cut to the depth of the pre-existing screw holes so I figured I was safe.

On close inspection after cleaning I see what might be a nascent irregularity in the barrel wall roughly under the dovetail cut. A warble can barely be seen, but now it's got me worried. I didn't believe the pressure on the barrel wall would be that serious at the very end of the rifling, but I may have been wrong. I've just never seen anything like this before.

Thoughts?

[Buck Elliott]

I recently cut a front dovetail leaving .050" of solid barrel at the thinnest spot out of a 1.5" thick barrel wall. My understanding is that this thickness is standard for a front sight, and I was using a standard front sight. I cut to the depth of the pre-existing screw holes so I figured I was safe.

On close inspection after cleaning I see what might be a nascent irregularity in the barrel wall roughly under the dovetail cut. A warble can barely be seen, but now it's got me worried. I didn't believe the pressure on the barrel wall would be that serious at the very end of the rifling, but I may have been wrong. I've just never seen anything like this before.

Thoughts?

I THINK -- you may want to recheck your numbers and give this another go... On and a half inches is a VERY HEAVY barrel wall... Most dovetails are cut to a nominal depth of .100" or one-tenth of an inch.

[Cosmoline]

Sorry I was getting tired. I should have said .150" barrel wall at the end with a standard .100" dovetail cut leaving .050" barrel thickness. I calipered it all out and I *thought* it would be fine, but with tactical light shining from below I can now see a distinct, if slight, warble under where the dovetail is, almost like the start of a bulge.

I was going to do a revamp of this rifle anyway so if I have to hack off the end it's annoying but not fatal. It needs to have a new half-length or 3/4 length magazine tube and front stock for other reasons. But among other things I was planning on doing a dovetail cut on the underside to lock down the magazine and prevent slippage under the fierce recoil. That worked for my Puma .44 Mag. If every dovetail is going to give rise to a bulge I may have to change my plans.

[uncowboy]

Forcing in a dovetail sight OR dovetail blank can cause a Dent in the rifleing. I am working out two right now. You want the sight to be tight but not hammered into fitting the dovetail. Tru slugging the dovetail and see if it is a Tight spot. You may have some work ahead of you. J.Michael

[Cosmoline]

Ah ha! I believe you're right--the bulge is going the OTHER way into the barrel. Mea maxima culpa. I go a wee bit excited with the brass tapper trying to get this ready for the weekend and may have wedged it in too hard while doing fitting. It's fitting fine now without getting too tight, but if you're correct then the damage has been done. I will verify bulge direction tonight.

If this is the case, is there a fix?

I clearly can't be trusted with tools

[marlinman93]

There may be a fix, but it might not fix it perfectly. I've had luck using a hard cast lead bullet and simply slugging the bore. Be sure the front sight is not installed when you do this. Just drive the slug past the dovetail and then back out the muzzle. It might take a few slugs to work it out, but it wont push it too far, as the muzzle will form the slug and then it will push out the low area as it passes.
Once you're done be sure to rework the front sight base so it wont push it back down again!-Vall

[AJMD429]

I clearly can't be trusted with tools

You're not alone...

[Cosmoline]

Thanks for the help! I reduced the indentation with some slugs and fixed the sight. A far as I can deduce, the problem was this: I had enough clearance directly under the sight, but on the sides when I drove it in, the edges encountered resistance and rolled up. As far as I can tell, the angle of the cut increased the pressure on the sides and they were forced down into the barrel, denting it along the lines of the cut. Thus the peculiar faint dents visible on the underside, which track the sides.

Live and learn.