fresh barrel and chamber... is this normal and typical?

[chop house]

most custom barrels i get my hands on are used. this is a savage prefit i actually ordered. i started measuring bullets for seating depth and was surprised at the minimal freebore. 6 x 45. i know saami specs out a reference measurement of 0.050", and there are a few threads discussing optimal freebore to get the most out of the cartridge with 80 and 90 grain class bullets. in this chamber everything but 70's eat up a lot of case capacity.

i am going to make a chamber cast, but in the meantime:

1. tooling marks a problem?

2. freebore typical unless spec'd otherwise?

thanks

 

[chop house]

 

[DaveTooley]

Two things jump out at me.
The rough lead angle with metal rolled off the edge. It's going to take sometime to smooth that out.
The other is the lands go all the way back to the neck. Not good on bullets and it means a large groove diameter.

 

[Tim Singleton]

Dont forget these teslongs magnify

 

[gunsandgunsmithing]

Dont forget these teslongs magnify

Yes. Each land is about .0035-.004" tall, total. Those tiny burrs at the trailing edge of the lands are virtually impossible to completely avoid by conventional chamber reaming. Hit it with some JB in the throat area and it may all go away and the tool marks will get a little better. Remember, total land height being .004 puts the tooling marks into perspective. Stainless has a tendency to "smear" a bit more than CM does. Grinding the throat would give a better finish but poses way more problems than it would cure. I agree with Dave about the bore being a tad big. But, all in all, I've seen way worse looking chambers. Do the jb and a proper break in, then let us know how it shoots. Just my 2 cents.

 

[Tim Singleton]

When a tiny piece of fuzz looks like a piece of string with these teslongs

Everyone needs to take breath on the chamber inspector thing

Mainest thing is does it shoot!

 

[DaveTooley]

I've said they are going to cause a lot of divorces. Machining leaves tool marks. Every reamer cuts differently and changes over it's lifespan. The key is to avoid the excesses.

 

[Tim Singleton]

Dave
I’ve had button rifled barrels cut like this before
Never a cut rifle barrel
Is it a big button that’s keeping the reamer from cleaning everything up right at the chamber mouth?

 

[bobm]

Dont forget these teslongs magnify

Yep..at least 30x or more.

 

[Rdlningcltchdmpr]

Remington 40 x bore cleaner will fix that throat fast.

 

[RGRobinett]

I dunno here are some Teslong pics of the lands (one of each land) in a new 3-groove PacNor 20VarTarg chamber I just finished, using a new Herniksen reamer. These are photos of the laptop screen, thus the "fuzzy/soft" look.
Compared to my Hawkeye, the Teslong images are quite good. I do agree - bore-scopes can mess with one's mind. To burnish OPs barrel, I would push a dry bronze brush through the barrel a few times, removing it at the muzzle between passes. Then shoot and see what you've got. RG

 

[DaveTooley]

Dave
I’ve had button rifled barrels cut like this before
Never a cut rifle barrel
Is it a big button that’s keeping the reamer from cleaning everything up right at the chamber mouth?

Tim
They manage groove diameter with the button and the bore size before rifling.
It doesn't mean the barrel is not accurate just on the large size. With trends going for very tight freebore diameters this happens. I can't say how much it effects accuracy, if any, if it's only slightly exposes the lands at the neck. The most important thing is concentricity. Then shoot it.
The target tells all.

 

[DaveTooley]

I dunno her are some Teslong pics of the lands (one of each land) in a new 3-groove PacNor 20VarTarg chamber I just finished, using a new Herniksen reamer. These are photos of the laptop screen, thus the "fuzzy/soft" look.
Compared to my Hawkeye, the Teslong images are quite good. I do agree - bore-scopes can mess with one's mind. To burnish OPs barrel, I would push a dry bronze brush through the barrel a few times, removing it at the muzzle between passes. Then shoot and see what you've got. RG
View attachment 1145699 View attachment 1145699 View attachment 1145701

Randy
A button rifled barrel I presume from the shape on the lands?

 

[RGRobinett]

Randy
A button rifled barrel I presume from the shape on the lands?

Dave, yes, PacNors are button rifled.

Though, to my eye, the original OP pic looks like a hasty job, I do not doubt that it will shoot well. I have seen much worse looking out shoot some which looked "perfect". Since I only do work for myself, and family, I can take my time doing the barrel work - don't have a dozen more waiting.

My primary reason for posting the pics was to exemplify Tim's accurate comment, "a tiny piece of fuzz looks like a piece of string with these teslongs" - very crisp and more magnification than the Hawkeye: my primary gripe is too much light!

Also, I talk to many people who believe that a tight (nominal caliber diameter) free-bore will provide more precision: they don't think about the possibility of larger groove diameter, & leaving a vestige of lands all the way back to the chamber mouth. Those I have been associated with, having that type of throat, have eventually shot pretty well. I'll take free-bore diameter 0.0005" to 0.0010" over nominal caliber every day - I like to see cleaned out grooves, with opposing groove & land swath "petals". RG

 

[STS]

Remington 40 x bore cleaner will fix that throat fast.

Absolutely. About 10 strokes on a felt pellet would solve most of that.

 

[carlsbad]

I dunno her are some Teslong pics of the lands (one of each land) in a new 3-groove PacNor 20VarTarg chamber I just finished, using a new Herniksen reamer. These are photos of the laptop screen, thus the "fuzzy/soft" look.
Compared to my Hawkeye, the Teslong images are quite good. I do agree - bore-scopes can mess with one's mind. To burnish OPs barrel, I would push a dry bronze brush through the barrel a few times, removing it at the muzzle between passes. Then shoot and see what you've got. RG
View attachment 1145699 View attachment 1145699 View attachment 1145701

RG,
While the cut and finish of your pacnor barrel looks great, I don't understand why the cut across the lands isn't a straight line. Looks like your land has a concave top much more concave than the radius of the bore.

--Jerry

 

[carlsbad]

To the OP and others. Yes, these things magnify, that's why we use them. We just nee to be able to interpret the results. The tool marks aren't optimal but probably won't hurt anything. This is a relatively inexpensive prefit.

The freebore is short. Unless you specify freebore, you don't know what you'll get.

Since you probably want deeper freebore, a sharp throat reamer would let you clean up the throat and increase your bore.

A little roughness in the throat will be worn off the first few shots. If the freebore is acceptable, shoot a few rounds and look at it again.

 

[DaveTooley]

RG,
While the cut and finish of your pacnor barrel looks great, I don't understand why the cut across the lands isn't a straight line. Looks like your land has a concave top much more concave than the radius of the bore.

--Jerry

Yep I've seen a lot of odd land configurations in buttoned barrels. Absolutely no correlation with accuracy.

 

[carlsbad]

Yep I've seen a lot of odd land configurations in buttoned barrels. Absolutely no correlation with accuracy.

thanks dave.

 

[Coonman300]

View attachment 1145624 View attachment 1145625

The marks that look like threads...are these what y'all are calling tooling marks? What is the black ring? Thanks