Not a Great Day for a Chamber (Pics Added)

[xr650rRider]

You can mess it up with a Dremel. I'll try the triangle file....

If George Carlin had been a gunsmith, Dr*mel would have been in his act.

 

[INTJ]

If George Carlin had been a gunsmith, Dr*mel would have been in his act.

Bruce did it with a Dremel and it came out perfect. I am not Bruce.......

 

[xr650rRider]

Bruce did it with a Dremel and it came out perfect. I am not Bruce.......

I think they also joked about Bruce being able to make a manual Bridgeport Mill perform like a CNC machine.

 

[INTJ]

Bruce happened to stop by as I was chambering this 338 Lapua IMP. I had him take a look. I had just started and was getting the little "U" at the end of each rifling. He grabbed an indicator he had in his pocket and showed me that the rifling had a low spot in the middle, and thus the U.

I just finished the chamber. I did it a 95 RPM and stopped the lathe before withdrawing the reamer. Didn't take much any longer than not stopping the lathe. The chamber looks nice.

I inspected it multiple times along the way. The best way I found when stopping was to just let go of the tailstock hand wheel, turn off the lathe, pull the reamer, then kill the flush.

There was a lot of flow with the modified reamer screw, and I turned the flush up all the way at times. I get paranoid when chips stop flushing out, which happened past 1/2 way in. I should have been able to make one pass, but I am just not confident in that way yet.

 

[dakor]

I have been cheating lately. If I take a screw meant for a smaller caliber and use it on a larger reamer (like a 6mm reamer screw on a 30 cal), it still holds the pilot but allows better flow.

My attempts at modifying the screws haven't gone well, but I do have extra screws......

JGS will cut oil groves in the screws for 8 bucks a screw and it helps letting the oil get past. I use a JGS floating reamer holder and really like it. What you are seeing I believe is an issue in that area with barrel.

I had the same issue one time and had plenty of shank so I cut 3/4 of the chamber off and chambered it again with the same reamer and bushing and it turned out good. No marks or anything so it had to be that spot in the barrel.

When I chamber with my power flush I back the reamer off slightly stop the lathe then back the reamer out to blow any chips off the reamer. I shut the pump off put the reamer back in until the shoulder bottoms out and then back it off .020 start the pump again then start the lathe up and make another pass. I cut about .060 at a time unless the barrel is being a pain and wants to gum up chips on the reamer. Than I will drop down to .040 a pass.

 

[tobnpr]

I had just started and was getting the little "U" at the end of each rifling.

Look like this?

Gunsmithing - Chambering anomaly- yeah, another borescope question...

but this one is different from any others I've seen. Just chambered this barrel. There are perfect half-moons cut ever so lightly into the grooves at the beginning of the leade cut- full diameter of the barrel. All perfectly symmetrical, all aligned radially meaning the bore was correctly...

www.snipershide.com

Groove diameter of the barrel has a larger radius than that of the reamer. I posted this thread on the 'Hide a couple of years ago, and got a great explanation. Makes sense to me.

 

[INTJ]

Look like this?

Gunsmithing - Chambering anomaly- yeah, another borescope question...

but this one is different from any others I've seen. Just chambered this barrel. There are perfect half-moons cut ever so lightly into the grooves at the beginning of the leade cut- full diameter of the barrel. All perfectly symmetrical, all aligned radially meaning the bore was correctly...

www.snipershide.com

Groove diameter of the barrel has a larger radius than that of the reamer. I posted this thread on the 'Hide a couple of years ago, and got a great explanation. Makes sense to me.

That makes sense to me as well. Doesn't seem to affect how the rifle shoots, and after a few rounds ams a couple cleanings it seems to go away.

 

[Judd]

The resources you have available to you, INTJ, I’m jealous of…man the questions and knowledge…

I had a 6.5 Benchmark barrel look just like that and the dang thing shoots great! I was worried and asked my mentor and he says…”yeah, you’ll see that in a button rifle every once in a while but they typically will shoot.” As always, he was right again.

Pretty crazy.

 

[INTJ]

First two pics are the marks in the chamber. The second two are a barrel stub I cut with that same reamer. There was a small chip weld on the reamer, and the second two pics show what those marks are. They are nothing like the marks in the barrel. I think the chip weld scratches would polish out.

 

[DShortt]

I'm going to have to go back and re-read this thread. That first image makes -0- sense to me based on what you described. Reflection has it looking weird or something.
The second ain't much easier to decipher.

The last 2 I can understand.

 

[LVLAaron]

I'm going to have to go back and re-read this thread. That first image makes -0- sense to me based on what you described. Reflection has it looking weird or something.

First one has that "I dont know if that's protruding or recessed" thing going on... It's the light.

 

[DShortt]

First one has that "I dont know if that's protruding or recessed" thing going on... It's the light.

Even if I invert it in my mind I can't make sense of it. Sometimes I have to sleep on things. Probably going to be one of those times.

 

[paperpuncher]

Even if I invert it in my mind I can't make sense of it. Sometimes I have to sleep on things. Probably going to be one of those times.

Try looking at the start of the most narrow groove in the 1st pic It shows a little better that it is grooved

 

[INTJ]

It looks to me like the barrel was torn.....

 

[DShortt]

It looks to me like the barrel was torn.....

Agreed. The magnification must be higher than what I'm used to and then the trick of the light as well.
It's a very interesting image. Thank you for posting it.

 

[INTJ]

Agreed. The magnification must be higher than what I'm used to and then the trick of the light as well.
It's a very interesting image. Thank you for posting it.

I think the Teslong is 3x. The Hawkeye, where I first saw it, is 8x. And has a better view

 

[SixFive]

Metal is a funny thing, I have turned and chambered hundreds of barrels in my life and early on it became obvious to me each was unique. Some have hard spots, some have voids (rarely) and as much of our barrel steel is now being sourced from China it is only getting worse. Have you seen the Chinese seamless tubing? OMG it has WAVES in it, I refuse to use it. I guess I am saying there is just no telling these days.

On another note, I guess I turn the reamer so slow in the lathe and retract and clean it so often I have never gotten chip weld, but I am not in a production environment so I am going sloooow.

 

[Dusty Stevens]

Metal is a funny thing, I have turned and chambered hundreds of barrels in my life and early on it became obvious to me each was unique. Some have hard spots, some have voids (rarely) and as much of our barrel steel is now being sourced from China it is only getting worse. Have you seen the Chinese seamless tubing? OMG it has WAVES in it, I refuse to use it. I guess I am saying there is just no telling these days.

You think we’re getting barrel steel from china now?

 

[SixFive]

You think we’re getting barrel steel from china now?

Yeah, we are getting a lot of steel from China and I tend to think some of it is ending up being used in barrels, I have no evidence but I am suspicious

 

[Alex Wheeler]

Look like this?

Gunsmithing - Chambering anomaly- yeah, another borescope question...

but this one is different from any others I've seen. Just chambered this barrel. There are perfect half-moons cut ever so lightly into the grooves at the beginning of the leade cut- full diameter of the barrel. All perfectly symmetrical, all aligned radially meaning the bore was correctly...

www.snipershide.com

Groove diameter of the barrel has a larger radius than that of the reamer. I posted this thread on the 'Hide a couple of years ago, and got a great explanation. Makes sense to me.

That can be true, it can go the other way as well or a corner can be cut deeper. Those issues show up as concave, convex, or angled looking cuts at the end of the throat. It also can be caused from reamer push off in a 5r. If you only see that in your 5r barrels, that is why.