New barrel chamber off center, 2 lands going back to neck... Pictures

[shinbone]

Maybe before you automatically send a rifle back to the Manufacture from just looking at it with a bore scope. Take pictures, contact the manufacture, and actually shoot the rifle.

I buy a brand new rifle, I want the chamber cut straight. It's on the manufacturer to make the bore, chamber, throat straight and concentric, not on the buyer to be beta testing the maker's QAQC short cuts.

JMHO

 

[tobnpr]

I am not a gunsmith, but the way I understand it, the lands being cut away more on one side than the other most likely happens when the chambering process is two steps. The first step cuts the chamber but not the throat, and the second step then cuts just the throat. This method is used to allow different freebore and different neck diameters. If the throating step is not carefully done, the cutter can get off center, perhaps where the throating reamer is unpiloted(?) and/or operated by hand(?).

Premium Uni-Throater Kit - Pacific Tool and Gauge

Premium Uni-Throater Kit at Pacific Tool and Gauge

pacifictoolandgauge.com

Not the case with factory rifles, or many customs for that matter.
For custom chambers that are "other than" SAAMI spec- whether freebore, leade angle, neck diameter, etc. it's always best to have a custom reamer ground to the desired specifications. Reamers are form cutters, can't end up with anything other than exactly what you've requested.

"Throating", or adding additional freebore, can and often is done as an additional step after cutting the chamber (or when an existing chamber needs to be modified for heavier bullets) as you mentioned- but it's never done that way on a mass-production barrel, always with reamers that cut the entire chamber.

 

[MNbogboy]

Certainly the moderately priced bore cameras (teslong) have caused a lot to worry when looking at mass produced factory bore condition.
Somevarevscary looking to say the least. Seeing the copper catching machine marks gives a person a good idea of what a good bore should look like. Those bore cams are the best cleaning aid you can get for seeing what is going on in there before and after cleaning. Before I bought One I can safely say I never had a clean rifle for over 60 years.
They are especially effective for seeing the progress in a multi pass cleaning with a bore paste like IN or Iozzo. Before and after views of a copper cleansing will show you how effective your copper cleaner is.
Carbon rings can also be diagnosed and inspected after cleaning. The bore cams can and are a great diagnostic tool for bore condition related shooting issues.

 

[RidgeTop]

Are you saying you want free-bore?

 

[MNbogboy]

Certainly the moderately priced bore cameras (teslong) have caused a lot to worry when looking at mass produced factory bore condition. Somevarevscary looking to say the least. Seeing the copper catching machine marks gives a person a good idea of what a good bore should look like. Those bore cams are the best cleaning aid you can get for seeing what is going on in there before and after cleaning. Before I bought One I can safely say I never had a clean rifle for over 60 years. They are especially effective for seeing the progress in a multi pass cleaning with a bore paste like IN or Iozzo. Before and after views of a copper cleansing will show you how effective your copper cleaner is. Carbon rings can also be diagnosed and inspected after cleaning. The bore cams can and are a great diagnostic tool for bore condition related shooting issues.

Are you saying you want free-bore?

When a round is chambered the bullethasto be somewhere Prior to ignition! The lack of freebie in the ops chamber, and mine,allowed the rifling to reach the case mouth. When chambered the bullet would be held skewed to one side. Whennfired the bullet would entertherifling at a slight angle.
A normal cut chamber would have a lead angle that let thevbulletenter full landentrapmentgradually.
I would have a hard time believing the off center chamber could or would not affect accuracy. We spend a lot of time getting the bullet to an ideal distance from the lands and experimentat the range finding the optimum distance. Only a perfect chamber allows us to dothis. The fluff developed in a crooked chamberisdifferentandbreak-in ofthecrookedchamber mistakes different number of shots oeradifferentlengthboftime.

 

[Muddyboots]

You are paying money for a product that performance can be dictated by the quality of machining. You expect and demand a "Quality" product, not something that would fail a gunsmith school build review. Its really that simple. Just because it will still shoot matters squat. Its not what you paid for and expect.

So you buy a vehicle but 5/6 cylinders are firing? Good enough? Still runs so what's the problem?

 

[RidgeTop]

Here is a pic of chamber end, muzzle and free bore. of rifling.
Chamber end, muzzle end, Weatherby free-bore.

 

[tobnpr]

We spend a lot of time getting the bullet to an ideal distance from the lands and experimentat the range finding the optimum distance

True, but that's only part of it.
It's critical for accuracy that once launched- the bearing surface of the bullet contacts all the lands at the same time so that they're evenly engraved into the jacket as it spins down the tube. Keeps the bullet perfectly centered and flying straight.

If the bullet contacts, say two of the grooves first in a non-concentric chamber- they'll push the bullet off-center enough to affect accuracy. We're talking a few thousandths of an inch, and milliseconds- but it's enough to manifest at the target.

 

[MNbogboy]

True, but that's only part of it.
It's critical for accuracy that once launched- the bearing surface of the bullet contacts all the lands at the same time so that they're evenly engraved into the jacket as it spins down the tube. Keeps the bullet perfectly centered and flying straight.

If the bullet contacts, say two of the grooves first in a non-concentric chamber- they'll push the bullet off-center enough to affect accuracy. We're talking a few thousandths of an inch, and milliseconds- but it's enough to manifest at the target.

Lands showing only on one side of the throat indicate .002 off center!

 

[BallisticsGuy]

Eeesh. What did they indicate that into the lathe with, a tape measure?

 

[MNbogboy]

It washardtoiaginewhatappened, exceptforthethreading crash. The tool scratched its waytote ten on shoulder and climbed right over the shoulder. My Guess was they started tochamberon the original indicatingaftertherash! No attempt wasmadetothreadte complete tenon cut. I was forced to chasethethreads withadie! The barrelhad been mounted & shot as It was copperedup real bad. The bolt nose relief cut was disallow for my 700 by about .010.which had nothing todowith theirsetup! I wastotallydissatifiedwitj thatbarrel and my plans area setback andthreadit for a brake.andrechamber in thefuture. Thiswasa handicapped barrel andcleans up easily. Forthemoneyi have in it I Hope that converting ittoa remake is my best chance to make a quality barrel out of it. Iknowicould sell it andretrievemypurchase price in a heartbeat.when the builder/sellerrefusedtowarateehiswork littledidhekow thatyembership in many different frumscoulddamage anyreputation he may have had.
I will not mention names as bashing anyone is a left liberal trickuseddailyonfacebook.