Thought on this Chamber cutting job

[argh]

Hi all. Just hoping to get some opinions on the finish of this chamber on a friends rifle (308). Rifle is a second hand target rifle that has not been touched since being bought. We do not know who the smith was or how long ago the barrel.was chambered.
Photos from a teslong bore scope.

Factory ammo fine, but 2nd and 3rd fired cases......

I know the bore cam enlarges any defects, but wanted some other opinions.

Fixes? I have my own theories, but wanted to hear from others.

Thanks
Adrian

 

[carlsbad]

Less than perfect. What is the problems you are experiencing in performance?

 

[Preacher]

Nice fire forming barrel right there.....

 

[338 dude]

Hi all. Just hoping to get some opinions on the finish of this chamber on a friends rifle (308). Rifle is a second hand target rifle that has not been touched since being bought. We do not know who the smith was or how long ago the barrel.was chambered.
Photos from a teslong bore scope.

Factory ammo fine, but 2nd and 3rd fired cases......

I know the bore cam enlarges any defects, but wanted some other opinions.

Fixes? I have my own theories, but wanted to hear from others.

Thanks
Adrian

Pretty rough

 

[argh]

Less than perfect. What is the problems you are experiencing in performance?

Fired brass ends up with a corresponding line about 1/8" below the shoulder..... aligns with the worst of the "scratches" in the chamber. Previous owner apears to have used factory ammo most of the time so no problems.
After 2 or three reloads on a piece of brass, the line becomes a ridge and locks into the scratch causing extraction issues. Loads are warm (45.4gr varget over 155gr VLD)
The action is an Australian Sportco Omark 44 (popular older target rifle), but they have notoriously poor primary extraction, so we end up with stuck cases.

 

[Gottschall]

Can you post pics of just in front of chamber?

 

[argh]

Can you post pics of just in front of chamber?

Needs a good clean. Second photo is without mirror looking down chamber. Shoulder area is pretty bad too.

 

[Pawnee Bill]

The Fix = new barrel.

 

[Bill K]

I guess you could try and polish/smooth up the chamber. But if that did not help, I would just re-barrel.

 

[carlsbad]

rebarrel or set back.

 

[Dusty Stevens]

I remember this when the lyman bore cam came out. With the $50 teslong its going to be even worse im afraid.

 

[argh]

I remember this when the lyman bore cam came out. With the $50 teslong its going to be even worse im afraid.

I know what you are saying, however the reverse is probably true on this situation.

This started as a problem extracting cases that i had been reloading for him. First loads were fine, then we had a couple of sticky extractions. So we set the shoulder back further, and had some lower charge weights. Got worse on the next round of firings, and we saw/felt a ridge on the brass. ....
We got out the Lyman borescope and saw this problem, the ridge on the brass aligns with the deep scratch on the chamber..... so dusty, it was the Lyman that diagnosed the problem. The rifle owner upon seeing through a borescope went out and bought the cheap borescope, and then sent these pictures to me.......... i thought i would share.
What Say You Dusty? Cheap borescope diagnosing a problem that isnt there still?

 

[argh]

I guess you could try and polish/smooth up the chamber. But if that did not help, I would just re-barrel.

Thanks, it looks like chips scratched the chamber when it was being cut. They are deep enough that it leaves a corresponding ridge on the case. We are trying to polish it out and will see how we go.
Rechamber might be the option, but we will need to set back a fair distance to get this grooves out

 

[carlsbad]

Sometimes a ring deep in the chamber is a botched prebore.

 

[Dusty Stevens]

No not this time. I do see a hurried chamber job and if you did see it on the brass it was definitely a problem.
Edit: this was not to carlsbad. His post snuck in while i was typing

 

[STS]

The reamer was as dull as a fence post. It was tearing the steel rather than cutting it.

 

[tobnpr]

^^^
X2

 

[argh]

Thanks guys. Worst chamber i have seen, my guess was not flushing the chips out and scratching the chamber walls, or blunt reamer. Barrel itself shoots good, and no problems using factory ammo. Fired cases however end up with a minor ridge that is causing extraction problems.

 

[Will Henry]

This is far from the worst chamber I have seen. A couple of questions: Is this a chromoly barrel or stainless? Just how much primary extraction is there?
It looks to me like the chamber could be fixed up with minimal set back. Depending upon to dimensions of the chamber, even honing might be adequate.
4140 does not ream as easily as 416 stainless and poor finish does happen on occasion if the gunsmith's technique is a bit lacking or even if he is just unlucky.
I would weld up the extraction cam surface on thebolt or the receiver (either will work) and recut it to maximize extraction. This is a not-uncommon necessity on the Sportco. WH

 

[AWLEAPHART]

Teslong bore scopes are whistle blowers
A Leaphart