Not a Great Day for a Chamber (Pics Added)

[INTJ]

I am too busy at work right now. My duties include communicating with customers of rifle builds and load development, answering general questions, overseeing load development, and overseeing rifle building. Right now, I am also cutting chambers and threading muzzles on one of our lathes.

So I went to the shop today on Saturday to try and catch up. I answered a customer e-mail, then went to the lathe. Yesterday I had managed to get a barrel ready to chamber. The tenon, threading, and bolt recess all came out very nice.

I had finished polishing the chamber. I was doing my final bore scope inspection of the chamber when I saw something funny. Circular abrasion looking marks just shy of the shoulder. Not scoring or scratching, but rough sandpaper looking marks that are much wider than a chip scratch. They weren't there when I was .400 from finishing and scoped the chamber.......

I tried polishing more, but it didn't touch the marks. I called a couple of gunsmith friends I have, and they had no ideas. So I gave in and ran the reamer in some more. .001" didn't change anything, neither did .005". Neither did another .015". However, I was now able to see that the marks were staying in the same place relative to the shoulder. Meaning that the culprit was likely the brand new JGS reamer.

The reamer looks fine to me, but I am not a reamer expert. I called a couple more gunsmiths and one did have a reamer I could borrow, but it has a smaller diameter neck. Meaning I would have to cut off 3/8" from the breech and chase threads, and I am not going to do that.

Most likely I'll have to buy a reamer and have it overnighted. Meaning I'll have to pull the barrel because there are way too many projects waiting and I don't have the time to let a barrel sit in the lathe for a couple of days.

To sum up, my five hours of work on Saturday put me further behind than I was when I started. My whole week seemed to go that way.

 

[littlebuddybr]

That sucks!!!

But it gets better.

 

[Dusty Stevens]

You cant look at it as putting you behind, this woulda happened monday or even tuesday, so you can really say youre ahead right now because you now know and are taking action. Run a stone on those cutting edges and call manson for a repair

 

[FireMedic]

I’m confused how it’s the reamer if you cut the chamber to within .4 of the finished length and the marks weren’t there….but showed up afterwards.

You should be able to run your fingernail on each flute of the reamer and feel if there is something amiss, chipweld, etc.

JGS reamers are the best available IMO.

 

[INTJ]

I’m confused how it’s the reamer if you cut the chamber to within .4 of the finished length and the marks weren’t there….but showed up afterwards.

You should be able to run your fingernail on each flute of the reamer and feel if there is something amiss, chipweld, etc.

JGS reamers are the best available IMO.

Me too.........

 

[JFrank]

IIRC you were suppose to be retired and enjoying life, not managing a shop full time.

 

[Henryrifle]

Besides looking less than perfect, what negative impact are you laboring to avoid? are you worried about extraction or engraving/marking the case?

What cartridge did you chamber?

I’m not seeing what you’re seeing, but this sounds like great is the enemy of good.

Hank

 

[INTJ]

I have a Hawkeye borescope. And while its images are not equaled, I can't take pics with it. They don't seem to offer the camera adapter anyone.

You can feel these marks with an angled probe tool, so they would mark brass.

Also, the reputation of the shop has been built on our outstanding customer service and good shooting rifles, of which I have chambered them all. I simply can't settle. I treat every barrel as if it was going on one of my LRBR rifles.

It's a 260 Rem on a Stiller Tac 30. While I dislike protruding bolt noses and sandwiched recoil lugs, in this case it's a good thing. I can set the barrel back a turn and clean everything up, and you'll never be able to tell.

I have never seen anything like these marks before. I am guessing something went away in the reamer while I was using it.

 

[Dusty Stevens]

If its making a gouge like that you should be able to feel that on the flute with a stone or old real copper penny.

 

[Will Henry]

I have long made it SOP to stone the face of each cutting edge between cuts. This is especially important on chambers with very little body taper. I check the cutting edges with my educated, super-sensitive, fingernail, and be sure each edge is smooth and clean. I have had reamers which started to pick up chips, and I had to hone them to get them cutting clean again. I once had a reamer which broke a piece out of one cutting edge. I simply ground that edge away so I had a reamer with one missing edge. It worked great! Never marked a chamber, never chattered. I replaced the reamer but really don't know why. WH

 

[okie]

Could have hit an iclusion in the barrel steel

 

[urbanrifleman]

I have long made it SOP to stone the face of each cutting edge between cuts. This is especially important on chambers with very little body taper. I check the cutting edges with my educated, super-sensitive, fingernail, and be sure each edge is smooth and clean. I have had reamers which started to pick up chips, and I had to hone them to get them cutting clean again. I once had a reamer which broke a piece out of one cutting edge. I simply ground that edge away so I had a reamer with one missing edge. It worked great! Never marked a chamber, never chattered. I replaced the reamer but really don't know why. WH

What kind of stone?

 

[ridgeway]

I use a flat ultra fine stone. It's flat, wedge shape that starts off like 1/8 and tapers to almost a point. I think I got it from enco, which MSc took over them. If I think of it I will snap a pic. Warning that stoning a reamer takes extreme care and finesse. Easy to make a sharp reamer dull..Haha

 

[shortgrass]

I use a flat ultra fine stone. It's flat, wedge shape that starts off like 1/8 and tapers to almost a point. I think I got it from enco, which MSc took over them. If I think of it I will snap a pic. Warning that stoning a reamer takes extreme care and finesse. Easy to make a sharp reamer dull..Haha

That's called a "knife stone", and is available in about any of the "India" grades. Don't know if it is available as a 'ceramic' stone, but it most likely is.

 

[Will Henry]

What kind of stone?

I use a fine, white ceramic on the face. A hard Arkansas is good too. I generally use a triangular stone, about 1 inch long. For sharpening, I use a somewhat coarser ceramic.
Ona chamber with more body taper, you can count on the last couple of cuts to clean up any flaws, but not so if the chamber is straight. WH

 

[LVLAaron]

These "Ruby" stones are excellent. There's a triangle stone in there that's handy for this application.

https://smile.amazon.com/gp/product/B0796T3CT7/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[INTJ]

If its making a gouge like that you should be able to feel that on the flute with a stone or old real copper penny.

I'll try that. I certainly can't see anything. It's tearing instead of cutting in this one spot

 

[INTJ]

Could have hit an iclusion in the barrel steel

I thought of that, but when the marks moved with the reamer it makes me think it's the reamer. When I find another reamer I'll know for sure

 

[Dusty Stevens]

Save that barrel for a bigger case in the future and try your reamer on a cutoff piece to see if it follows, then youll know if you need to keep on the new reamer path or another barrel path

 

[INTJ]

Save that barrel for a bigger case in the future and try your reamer on a cutoff piece to see if it follows, then youll know if you need to keep on the new reamer path or another barrel path

Can't. It's a customer supplied barrel.