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

[Alex Wheeler]

You wont see lands on a button cut straight (most buttons) , or even the grooves for that matter. A straight looking cut will only happen if the radius of the top of the land or groove is exactly correct for its diameter. Since most buttons will have a cupped land,(compared to the perfect radius) usually .0002-.0003" worth, you will see the cut lower in the center. The button forms wings on the land. The opposite happens in the grooves usually. Cut barrels will usually have a straighter looking cut because the bore (land radius) is close to as reamed and the groove is shaped by a cutter which is ground as close to the correct radius as possible usually. I have been watching all the geometry in different barrels for some time and all the end user really needs to look for is consistency from land to land and groove to groove. They should all look the same. The shapes you see are a result of the button or cutter, and mostly will not play a role in accuracy.

OP, your freebore looks close to .050" and I'd say the freebore diameter on the reamer is too small. Groove diameter could also be on the big side, but Id bet on the reamer.

I have been posting a little info on this on my fb page. Since these cameras are so cheap and good now, I feel people should understand what they are seeing

https://www.facebook.com/video.php?v=953319295067001

 

[STS]

^^^^^^^
Killer reamer and well driven too.

 

[bobm]

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

From what I read this is a new unfired barrel. That would eliminate carbon as the black ring. I think what you are seeing is the end of the chamber has a 45 degree angle instead of a sharp corner. The reamer has a corner break on that edge. Keep in mind the 30 X plus magnification of the view. The light is not reflected the same on the angle as the horizontal surfaces and appears darker. My bet would be that is a .010 width angle or less.

And yes, those are tool marks left behind from the rotating reamer. (or barrel)

 

[DaveTooley]

The black ring in Randy's pics is the end of the neck as it transitions to the throat. Any removal of metal leaves marks.

 

[chop house]

First.... A huge thanks to the experienced shooters and smiths that responded. Priceless info. I have been out of the loop for the holidays but have started to assemble the rifle. i used iosso to get a partial cleanup of the throat and gained about 0.010 freebore so i must have removed at least one offending burr.

in the meantime i contacted the manufacturer for the dims and they quoted straight from saami. 0.049 freebore. (right on, Alex) i will use inexpensive 70's (read tnt's) for extended break in and then reassess whether to have the throat reworked to shoot 87's more efficiently.

thanks again, all!

 

[chop house]

 

[Tommie]

BY FAR one of the best discussion threads in a long time. Full of intelligent, experienced information with zero bickering.

My faith in mankind is rekindled.

 

[RGRobinett]

BY FAR one of the best discussion threads in a long time. Full of intelligent, experienced information with zero bickering.

My faith in mankind is rekindled.

Yes, indeed!
Dave Tooley picked-up on the button rifling vs cut instantly - that is EXPERIENCE - earned and shared! Then Alex Wheeler explained it - the differing geometry -very well: his explanation should be read and re-read - and saved near one's new scope! It's UNIFORMITY, as opposed to specific pattern, which is desirable.

The OP's last post and comments confirm another attribute I often hear about and discuss: the "throat" moving forward/lengthening rapidly and substantially over the course of only a couple of hundred rounds. Usually, people advise that they cannot obtain a traditional, "square land mark", pattern on the bullet-nose a long-seated dummy round. Then, the throat "moves" forward - sometimes I'm told, as much as 0.030"" in the first couple of hundred rounds, then, obtaining the land pattern becomes possible . . .

This barrel does not have a true free-bore, but, rather a very shallow vestige of lands all the way back to the chamber mouth: this stops the bullet artificially short of where, based upon a reamer print, one would expect. Then, these "ghost" lands erode rapidly, until the bullet nose radius contacts the actual cone surface, whereupon, seating control , "normalizes". I would expect the OP's barrel to exemplify this behavior.

Merry Christmas, to all! RG

 

[Dusty Stevens]

BY FAR one of the best discussion threads in a long time. Full of intelligent, experienced information with zero bickering.

My faith in mankind is rekindled.

Lets talk about neck sizing for this barrel.

 

[Tommie]

Lets talk about neck sizing for this barrel.

You are full of meanness...

 

[MNbogboy]

Is this the worst throat anyone has ever seen? I've certainly seen none. The grooves reached the case mouth on one side.
The barrel smith said it was a perfect chamber. Not bad if done with a right angle hand drill!
He refused to refund my money but offered me credit on another one. Would you trust his work? Still hard to believe he is a player in the barrel business. This was a shouldered rem 700 he had done for another customer that he sold on ebay.
His reputation for prefits has been pretty good but why would he jeopardise it by peddling his rejects??
Can't believe he's still in business with an attitude like that. He even refused to look at the Teslong pictures.

 

[Nightraider]

View attachment 1147820 Is this the worst throat anyone has ever seen? I've certainly seen none. The grooves reached the case mouth on one side.
The barrel smith said it was a perfect chamber. Not bad if done with a right angle hand drill!
He refused to refund my money but offered me credit on another one. Would you trust his work? Still hard to believe he is a player in the barrel business. This was a shouldered rem 700 he had done for another customer that he sold on ebay.
His reputation for prefits has been pretty good but why would he jeopardise it by peddling his rejects??
Can't believe he's still in business with an attitude like that. He even refused to look at the Teslong pictures.

Pva?

 

[MNbogboy]

Pva?

No, and I won't smear anyone because of their arrogance or lack of common sense.
This may have cost me a big chunk of my monthly retirement check but what I am illustrating is the value of a bore camera.
It may save someone else the pain of accepting a flaw in a barrel that they would not have normally seen.

 

[jds holler]

Yeah, but how does it shoot??jd

 

[Gappmast]

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?

Remember a reamer can't put metal in.

 

[MNbogboy]

View attachment 1147900

Yeah, but how does it shoot??jd

As ticked off as I was after talking to him I went directly into my "shop" and headspaced it to my 700. The bolt nose was too shallow and I had to deepen it. You could see on the shoulder & tenon where the tool crashed into it during threading. I surmised the half nut stuck on him and he did not check setup again before chambering...real "hack" job.
Reamer must have had a small pilot or none at all to accomplish this....
Long story short without real load work up had it shooting .5s, .6s....in 53 shots.
Shot 54 took a big 8 pt. Whitetail with it 2 days later. It now sits in the safe waiting it's turn!

 

[4isnaf]

I thought it would be best to post it here instead of starting a new thread...

New Krieger barrel I just got back from my gunsmith. The 6 Dasher chamber was cut with a new JGS 1300 reamer that I bought and is smooth.

Throat was cut with a throating reamer he already had.

You guys with experience in chambering, would you agree it's a crappy job?

Thanks

Naf

 

[jackieschmidt]

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

PacNor barrels have lands that are a convex shape, it is one of their selling points, hence the reamer cuts more on the top Of the land, giving it a parabola shape.

 

[divingin]

Yep..at least 30x or more.

Kind of depends on the screen size. Put it on your 64" TV and it would be a lot more than that.

 

[dakor]

My 6x45 reamer has .85 freebore. It works good all the way up to 105 bergers. But even with 75gr bullets if you want to be close to the lands and use the magazine box on a Rem 700 short action you have to take the spacer out of the box to get them to fit.

So .050 fb would be about right for a SAAMI reamer. If you want a longer throat you could get a 6mm throater or send it to someone to have it done.