Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Gunsmithing


Reply

Bore not concentric with OD of Custom barrel & qualifications

 
LinkBack Thread Tools Display Modes
  #1  
Old 01-28-2011, 12:22 AM
Bronze Member
 
Join Date: Apr 2008
Location: South Texas
Posts: 55
Bore not concentric with OD of Custom barrel & qualifications

After installing a muzzle brake on a specific rifle I ran the whole process over in my head and most of what I recall, I either didnít understand or appreciate it.

The bore is quite offset from the OD. What makes it shoddy looking or ugly is the fit is pathetic where barrel meets brake.

This rifle shoots OK at bestÖmaybe 0.75 MOA at 100 yards, then it wonders out further.

For those who have experience in purchasing and fitting custom barrels, what are the simple checks you perform that tend to detect conditions that lend poor accuracy performance? Naturally, I am focusing on barrel blanks that have not been machined for fitting.

What or how many squawks will you compile before you send it back for a replacement?
Reply With Quote
  #2  
Old 01-28-2011, 08:50 AM
Platinum Member
 
Join Date: Jul 2004
Location: Texas
Posts: 5,495
Re: Bore not concentric with OD of Custom barrel & qualifications

Quote:
Originally Posted by blackbrush View Post
After installing a muzzle brake on a specific rifle I ran the whole process over in my head and most of what I recall, I either didn’t understand or appreciate it.

The bore is quite offset from the OD. What makes it shoddy looking or ugly is the fit is pathetic where barrel meets brake.

This rifle shoots OK at best…maybe 0.75 MOA at 100 yards, then it wonders out further.

For those who have experience in purchasing and fitting custom barrels, what are the simple checks you perform that tend to detect conditions that lend poor accuracy performance? Naturally, I am focusing on barrel blanks that have not been machined for fitting.

What or how many squawks will you compile before you send it back for a replacement?

The very first thing I do before starting a re barrel is to place the barrel between centers on the
Lathe and indicate it from one end to the other first checking the shank(Breach)end and every
6" until I reach the muzzle end.NO MATTER WHO's BARREL IT IS.

I turn the barrel at least 2 revolutions at each location and right down the out of round/concentricity
of the barrel off the bore.

Some barrels have huge issues because they have been straightened after drilling and
contouring even though the bore is straight.

This condition makes the barrel thicker on one side than the other and as the barrel heats up
It expands at a different rate from one side to the other.(Common with factory barrels and
the reason that after a few shots and the barrel warms up the POI or group size changes)>

I will except .003 to .005 thousandths of "Total Indicated Run out" but no more. I am not smart
enough to know How much is OK, I just know that perfect is OK for sure, and that the barrels
that have been replaced (Because they would not shoot) were .010 thousandths Plus.

I have been told by some barrel makers that .007 to .010 was exceptable (But they make the
barrels and want to sell all of them),

After talking to one barrel maker , he said that there is no good reason that a barrel should be
more than a few thousandths out of concentricity from the bore.

I have used over 25 of his barrels sense and found "NONE" that were over .002 end to end and
less than .001 around the bore.

As I said even after 25+ of his barrels I still check every barrel.

On the barrels that were under .005 out I turned the OD true to the bore for chambering and
installing a break on those other brands, and those that were more than .005 went back.

I even had one guy tell me that no one checked center to center on custom barrels because
he had never a rejection. Obviously I did not believe him (There are to many good Smiths
out there).

Everything must be concentric from the bore in order to have concentric threads and chambers.
(A must for accuracy) Why blue print an action and then install it on a crooked or out of round
barrel?

Maybe some of the other guys will chime in and give there opinion on this.

I also don't know how much off center the threads and the bore of a break can be
before it effects accuracy so I cut the threads on the lathe to center and bore the finished
diameter of the caliber hole+.020 with the brake installed on the barrel still in the thread
setup stage for concentricity to the bore. I do feel that any off center condition can't be good
especially if the bullet contacts the break.

I have My comfort zone and others may have a different opinion but Perfect is still best if
one can achieve it.

J E CUSTOM
__________________
"PRESS ON"

Last edited by J E Custom; 01-28-2011 at 11:00 AM.
Reply With Quote
  #3  
Old 01-28-2011, 10:18 AM
Silver Member
 
Join Date: Oct 2010
Location: Watertown, SD
Posts: 322
Re: Bore not concentric with OD of Custom barrel & qualifications

I have worked with many barrels and like JE stated there are some that are very bad. The best I have seen to date have come from Brux, I have 1 .224 1/8 twist barrel from them that was only .0002" off. A lot of the lower end barrels are going to be farther off just because the lack of time and money put into them, if they sell a blank for $100 they can't spend 4hrs finishing it. You get what you pay for in barrels.
Reply With Quote
  #4  
Old 01-28-2011, 10:20 AM
SPONSOR
 
Join Date: Mar 2010
Location: on the Southern Plains
Posts: 1,149
Re: Bore not concentric with OD of Custom barrel & qualifications

I always indicate a barrel in using the bore not the outside. Goes for both ends, tenon for screwing into the receiver, threading for muzzle break. Dial in on the outside to match break to barrel.
__________________
"Shoots real good!": definition; it didn't blow-up in my face. Not everything can be fixed on an internet forum!

Last edited by shortgrass; 01-28-2011 at 07:51 PM.
Reply With Quote
  #5  
Old 01-29-2011, 11:40 AM
Bronze Member
 
Join Date: Apr 2008
Location: South Texas
Posts: 55
Re: Bore not concentric with OD of Custom barrel & qualifications

Quote:
Originally Posted by J E Custom View Post
...told by some barrel makers that .007 to .010 was exceptable (But they make the barrels and want to sell all of them),"
J E CUSTOM
Good point/s. I would presume there are many different barrels (with respect to quality) as there are shooting disciplines. I should have narrowed it down considerably...

And, yes sir, I bet .007"-.010" may be adequate for say a hunting rifle used in areas where 100 yards or less shots are the norm. I don't know but some smiths may have a tendency to build for their area's uses. (And I am on longrangehunting's website, not that-ought-to-be-about-right.com)

For long range use that will result in precise accuracy what other "tests" will you insure the barrel meet/exceed?

Borescope inspection?

Pushing a lead slug through it?

How important do you feel conveying the intended use or precision demands to the barrel maker is?

Is there any "somewhat" consistency in quality control with those that produce accurate precision barrels?
Reply With Quote
  #6  
Old 02-05-2011, 05:15 PM
Platinum Member
 
Join Date: Apr 2003
Location: North Bend, Oregon
Posts: 1,220
Re: Bore not concentric with OD of Custom barrel & qualifications

Quote:
Originally Posted by shortgrass View Post
I always indicate a barrel in using the bore not the outside. Goes for both ends, tenon for screwing into the receiver, threading for muzzle break. Dial in on the outside to match break to barrel.
I am with Ted on this one. Thread, chamber and crown from the bore centerline 2.5" to 3" on each end and then dial in on the outside when contouring the brake to match the barrel.
__________________
Build a man a fire and you heat him for a day.
Set him on fire and you heat him for life.

Only accurate rifles are interesting.

Gordy and Brady.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Bore not concentric with OD of Custom barrel & qualifications
Thread Thread Starter Forum Replies Last Post
Bore size of 7mm barrel? desertbull Rifles, Bullets, Barrels and Ballistics 6 10-17-2010 06:54 PM
Custom rifle builder & gunsmith qualifications? teddy12b Rifles, Bullets, Barrels and Ballistics 4 02-23-2009 10:09 PM
concentric ammo and velocity jmason Reloading 3 10-30-2008 08:18 AM
neck trimming,tension,concentric,will it help? bsb Reloading 12 12-03-2007 09:09 PM
Large Bore Barrel BABore Rifles, Bullets, Barrels and Ballistics 1 12-31-2004 10:21 AM


All times are GMT -5. The time now is 08:41 AM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC