Gunsmithing Bore not centered in barrel...

[LiveToDrive]

So I ordered this Savage prefit for my Origin action. They had a 26" in stock or I could wait 3 or 4 months to get a shorter one. I bought the 26 and brought it to LRI to cut it down. I go to pick it up and the say they noticed... Long story short, the bore is almost 30 thou off center. Even if it shoots, I can never unsee how off center that freakin hole is... Not sure what I'm gonna do, just venting...

 

[Cryptic]

Did they mention if they checked to see if the chamber is concentric with the bore? If it is, and the threads are concentric with the chamber and bore, you could still have a winner. Regardless, if the barrels already been cut down, it's very likely still your baby, and you may as well try it anyway. You could call the people you bought your barrel from and ask nicely about it, but I wouldn't be surprised if they decline to offer a replacement on a cut down barrel.

 

[Supersubes]

The very first GAP rifle I ever bought had a very crooked bore. Like obviously off center. It was a rock creek blank which they chambered in .260. Holy shit was that thing a laser. I considered calling George and griping, but I knew his very first question would be “how’s it shoot?”. Fuckin awesome George! He’s a fairly salty dude, and would have told me to GTFO.

I have an acquaintance who works for a barrel company now, who back in the day chambered a barrel that was .080 off center. He’s a benchrest competitor and slapped this particular barrel onto his unlimited class bench gun, and showed up to a National with zero rounds down it. He re-set the group or agg record(I don’t recall) with it.

 

[918v]

How do you not run out of scope adjustment with the bore that much off?

 

[buffybuster]

Deep hole drilling is tricky and having the hole off center is more common than thought. As long as the chamber is cut well, the off center bore shouldn't affect accuracy. That said, if it was a shouldered barrel, the smith can time the barrel so it's off center at 12:00 o'clock. The other theoretical issue (depending on the contour) is since the barrel wall is not concentric as the barrel heats up it could start walking. Again largely theoretical.

 

[Threadcutter308]

Ummmm, guys, the bore is cut (gundrilled) and rifled when the blank is a straight piece of round barstock (when it is at it's strongest), then the exterior contour is cut. It's more like the exterior contour is not concentric with the bore. Bores are rarely straight, mostly being slightly banana shaped. I always find the concave side of the bore, breach to muzzle, when dialing in to the lathe and point/index it to the 12:00 position.
Honestly, I have found fairly consistent lack of concentricity of contour to bore with numerous different manufacturer's blanks. As long as the person chambering the barrel dials the blank in to the lathe using alignment/indicator rods in both the breach and muzzle bore ends of the blank simultaneously, it doesn't matter what the contour does/looks like. Just never "re-index" off of the contour, if you originally indexed off of the bore at both ends. To do so then introduces the diametrical error(s) of the differences between the bore and contour concentricities.

In other words, the contour of the barrel not being "concentric" with the bore is of very little, if any consequence. Think about it; do you want the chamber to be concentric with the bore, or with the contour ? You can't have both.

Oh, and in regard to; "I can never unsee how off center that freakin hole is... Not sure what I'm gonna do, just venting..."
I get it, but forget you ever heard it, go shoot it and if you are handloading, work up a load just as though it was a "perfect" new barrel. LRI is a top notch outfit, and I suspect they may have told you about it so that if on the off chance they didn't say anything and you came across it on your own, "you" (speaking in generalities) wouldn't turn around and blame them. In LRI's defense (not that they need any), there is nothing they could have done, either accidentally or intentionally that would have introduced the lack of concentricity. It was that way when it was manufactured originally.

Oh, and another thing; What is the most critical component/dimension of a barrel's trunion/chamber besides the concentricity of the chamber to the bore ? It is the Shoulder of the barrel trunion and it being perfectly square/perpendicular to the bore, the chamber, the breach/trunion face of the action and the bolt face. Another big reason that barrels are always aligned in lathes by using bore indexing rods (and not even looking at the contour).

 

[Edds]

... Long story short, the bore is almost 30 thou off center. Even if it shoots, I can never unsee how off center that freakin hole is... Not sure what I'm gonna do, just venting...

Have someone fix the look. It is an easy fix.

 

[LiveToDrive]

Thanks guys,
Just to be clear, I know LRI has nothing to do with how this barrel was built. I'll probably have them build my next barrel. I'm just going to shoot this the way it is, I'll probably build another rifle next year anyway. If this one shoots good, I can always throw this barrel on one of my kids rifles.

 

[BCX]

That would drive me crazy but we shouldn't be looking at the muzzle while shooting lol

 

[Steel head]

I’d absolutely be shooting it

 

[dustingaunder]

I cut off a factory Tikka 300wsm barrel yesterday. Bore was close to OD at muzzle. Chopped 6” off and zeroed the bore. OD runout was 20 thou or so. 25 completely cleaned up the cut. Pretty common In my experience. Never been an issue outside aesthetics of fitting a thread protector or muzzle brake.

 

[LiveToDrive]

That would drive me crazy but we shouldn't be looking at the muzzle while shooting lol

Shit, you're saying I'm doing it wrong?

 

[FisherT&C]

This is nothing to even consider, I don't even know why they bothered to mention it. Just shoot it and forget the .030, that's just needless bullshit to carry in your head.

 

[dustingaunder]

I did a Remington 700 25-06 a couple months ago that the bore was off from the OD substantially at the muzzle. Old gun, 6 digit serial number. I cut off about an inch and a half to remove the screw holes from the front sight and threaded. It took probably 40-50 thou to clean up the cut. It was the nastiest one I've ever encountered. Rifle shoots fine and now quiet. Just looks funny when you look at anything mounted on it or at the muzzle. Very noticeable to the eye.

 

[BJames]

This year my smith spun me up a 7 saum, with a tube from a reputable barrel maker. When I took delivery, he pointed out how “crooked” the bore was in relation to the contour. I can only tell when the thread protector is on honestly. It shoots lights out, and with a Area 419 adapter on it, doesn’t seem off anymore ?

 

[Threadcutter308]

Guys, with all due respect, the bore will never be perfect, but it is by far, the straightest, most concentric thing on/in the barrel. As I said above, the contour is cut/ground/sanded AFTER the bore is rifled.
Depending on how the manufacturer sets the barrel up to be contoured (live/dead centers with drive dog, or chucked up with no reference to the bore) will determine just how far out of concentricity the CONTOUR is in relation to the BORE. It is not at all accurate to say/think that the bore is out of concentricity with the contour. It is exactly the opposite.

 

[LRI]

Did they mention if they checked to see if the chamber is concentric with the bore? If it is, and the threads are concentric with the chamber and bore, you could still have a winner. Regardless, if the barrels already been cut down, it's very likely still your baby, and you may as well try it anyway. You could call the people you bought your barrel from and ask nicely about it, but I wouldn't be surprised if they decline to offer a replacement on a cut down barrel.

No, we didn't. We were asked to shorten a barrel and thread it. That's what we did. The simple facts are here that regardless of what one thing or the other is doing, the only way to know if something is truly "broke" is to go shoot it for record.

I had one barrel manufacturer that routinely made this very issue a problem for me. The guns always shot great, but the musical chairs game where I had to explain myself got old, so they got the punk.

 

[LRI]

How do you not run out of scope adjustment with the bore that much off?

I can do an awesome job of drilling a hole. I can also totally goof the OD contour. This has zero influence on where the bullet goes or where the optic is pointing.

The only exception to this might be a barrel that sees a higher cyclic rate of fire. Then the side that is "fat" is going to tend to grow more since it has more mass. This can push the barrel slightly and result in a wandering zero.

 

[LiveToDrive]

Once again, I really enjoyed working with the folks at LRI and I apologize for dragging them into an apparent "bore-off-center-does-it-matter" debate. I'm over it and I'm sure this barrel will shoot fine, but I can still be a little annoyed that my suppressor looks crooked on my not inexpensive rifle. I'll post pics of some off-center load development after my new rings come in. THANKS Y'ALL!!!

 

[Cryptic]

No, we didn't. We were asked to shorten a barrel and thread it. That's what we did. The simple facts are here that regardless of what one thing or the other is doing, the only way to know if something is truly "broke" is to go shoot it for record.

I had one barrel manufacturer that routinely made this very issue a problem for me. The guns always shot great, but the musical chairs game where I had to explain myself got old, so they got the punk.

I sure hope you didn't get an idea that I was criticizing you in any way. I was just trying to lead the OP to the logical next step being live fire.

 

[LRI]

I sure hope you didn't get an idea that I was criticizing you in any way. I was just trying to lead the OP to the logical next step being live fire.

Nope. Not at all.

 

[deadly0311]

I shortened a truck axle like that. Bore was centered to within a 10th. I’d bet there was 80-90 thou of runout. The first couple of light touch passes were interrupted cuts. Gun shot great before and after, but the muzzle brake looked odd having a noticeable bias to one direction

 

[wnroscoe]

These threads crack me up. Thanks.....................

 

[ugsly308]

see it a lot when shortening barrels, just shoot it......

Casey

 

[308pirate]

This is a perfect example of information in the hands of those that don't understand it.

@Threadcutter308 is 100% on the money

 

[jackinfl]

If I lived close enough to LRI, or any of the Top Gunsmith's that contribute here, to drop off and pick up at their shop. I'd have them do the work for me. They'd probably trespass warn me.... Or, if I could figure out what coffee or beer they like maybe they tolerate me...

 

[1moaoff]

I think chad smokes pall mall...

 

[Wannashootit]

Shit, no revelations here.
It's why we don't just throw the barrel in a 3-jaw and shove a reamer down the bore.

But, .030 is a lot, by anyone's standard. You'd clearly see the barrel OD offset at the receiver face, and if it were a barrel with a 1.300 breech it would be hanging out past the receiver on one side.

 

[Twins82]

Once again, I really enjoyed working with the folks at LRI and I apologize for dragging them into an apparent "bore-off-center-does-it-matter" debate. I'm over it and I'm sure this barrel will shoot fine, but I can still be a little annoyed that my suppressor looks crooked on my not inexpensive rifle. I'll post pics of some off-center load development after my new rings come in. THANKS Y'ALL!!!

Mine hangs low and right, and works well