Gunsmithing barreling timing
- Thread starter tickridge
- Start date
Timing is done in the lathe when setting the shoulder of the tenon.
Its importance is arguable. How much difference it makes is an unknown, dependant on other factors. To my knowledge, no-one has done an empirical study to verify its effects.
How to measure it, is to set the barrel up in a lathe and use a long reach indicator to measure runout in at least 2 different locations. That will give you it's direction and some indication of its magnitude.
How to measure it, is to set the barrel up in a lathe and use a long reach indicator to measure runout in at least 2 different locations. That will give you it's direction and some indication of its magnitude.
Do you mean you’re about to chamber/thread a barrel for a certain action, or you’re assembling a prefit onto a action?
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Where your barrel indexes has already been decided then. Screw it on and enjoy!
I'm not planning on gunsmithing, just learning more about rifles, so I grabbed this thread from a search on the subject.
A smith I recently bought a rifle from described to me how one of the more careful things he does is to "time" the barrel (I didn't know what it was called), making sure the un-straightness ,or deviation from straight, on a barrel is pointed at 12:00 (or 6:00?). My question is why?
If the shooting error is exactly the same every time, you adjust scope to compensate when sighting in, so why would it make any difference what direction the deviation rests? Maybe you answered this above; nobody knows, so why do it?
What kind of tolerances are we talking? How many thousandths off straight might an acceptable new 24" hunting barrel be?
Timing it at 12:00 gets you extra elevation.
We do it because it’s an easily controllable variable on our end. The amount of deviation in the barrel as manufactured varies.
Banana pointed up to 12:00 O'Clock at the muzzle FTW !............
(Oh, and never index off of the exterior/contour, always off of the bore........)
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It's baseline effect is on POA vs POI , and more specifically cold bore shots.
The second issue is for sustained strings of shots. As a hollow steel rod (barrel) get hotter they usually get straighter (even heat, non localised, saturation, etc) and hot barrels tend to shoot marginally faster.
I spent a bit of time experimenting with this a few years back. There's lots of factors, such as cro-mo VS stainless, caliber, profile and length.
It does make a measurable difference. I never released my findings or any data on it as no one wanted to know (or ever asked). Everyone just says "time the barrel".
For quality after market barrels, the effect is almost irrelevant, but 'smiths still don't as customers read too much on the internet.
I time the high side of muzzle runout to 12. Does it help, not sure. It doesn't take that much extra time to do so and it makes me feel better.
Casey
Casey
I would tend to agree. If you could see how much that barrel whips upon firing, you might not be so concerned about barrel timing on an already assembled gun. Plus, I lost four inches of elevation on my gun just by screwing on a break. It didn't affect the grouping at all. It just made everything shoot about 4 inches lower at 100 yds.
Does timing the muzzle runout at TDC guarantee that the attitude of the bore is in an upward direction? One would have to assume the bore makes a continuous and consistent single plane arc for this to be true.
Personally, I feel bores are far straighter than the internet would lead you to believe. There certainly are exceptions.
Personally, I feel bores are far straighter than the internet would lead you to believe. There certainly are exceptions.
I’m pretty much in agreement. I index barrels to 12:00 o’clock because I have already done 90% of the required work by just dialing in the barrel/bore to be concentric in the headstock. The extra 10% work isn’t a big deal. Do I emphatically know if if makes a difference? No. But doing it is low hanging fruit/easy, so why not ?
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You guys think like me. I'm not a gunsmith but I build things, and I go out of my way to get straight and centered just to know I got it straight, even if it is going to be hidden. Drives my co-workers right up the wall, which I suppose is part of the satisfaction.
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This is exactly it. Button or cut, the quality of barrels now is excellent. By now mean "this point in history compared to other years previously.". Sure they can get better, but I don't know how, they are great.
This is an interesting, often debated topic. I am in your camp...
I believe it's barrel harmonics that contribute to accuracy- "OCW" theory.
Getting the bullet to exit the muzzle when it is at the optimal, repeatable location in space.
This video is exactly what you're referring to:
Now, the bullet is long gone outta the bore before most of the garden-hose whip we see- but there is definitely motion at the muzzle before it exits.
It's really impossible to confirm one way or the other, can't change muzzle "timing" without also changing another variable rendering the experiment moot.
This is a curiosity question - how many thousandths out of straight would an acceptable 24" barrel be? Would it be visible to the naked eye looking at a light down the barrel? Of course I realize it varies, but what deviations have you measured and accepted? Or do you not get a measurement, you only get the orientation of a deviation and time it?
Your question tends to indicate that you are of the understanding/belief that the contour is cut first, then the bore is cut and finally rifled. That is not the case.
The first thing to happen is the bore is cut, then rifled and the last thing to happen is the contour is cut/ground/sanded.
Other than the quality of the steel, the only thing I really care about is the quality and concentricity of the bore and rifling. Oh, and BTW, the only people that have any control over that are the barrel manufacturers. Gunsmiths have no control over it. The most important thing I can do when chambering a barrel is to dial in the bore to as close to being as perfectly concentric within the headstock as possible. I can usually get both ends within .0002” of perfection. That way, the chamber will be as close to “perfect” as possible (they always have some runout, but obviously, the less, the better). The same is true of the trunion shoulder, it must be as square/perfectly perpendicular to the bore as possible.
People need to get away from this idea that the contour is cut first, then the bore is cut and if the reamer doesn’t come out the other end of the 30” blank exactly centered, it’s a bad barrel. It just doesn’t work that way.
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The easiest way to see it with your eyeball is to take a fired case, knock the primer out, drop it in the chamber, then point the chamber end at a light source while viewing from the muzzle end. A perfectly straight bore will show concentric rings throughout its length. Where the bore deviates, those rings will deviate. Beyond being interesting, it’s not useful. We can measure it every which way, but in the end what matters is a bore coaxial chamber and a clean perpendicular crown.
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This
Besides, if it “isn’t concentric”, what do you do about it/how do you fix it ? (hint; you don’t, you can’t. You finish chambering it and go shoot it).
Oh, and Mother of God, please do not buy a borescope.....
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I have used my Hawk eye bore scope to look at many many chambers from others and on prefits. I have seen some that were down right fuckin ugly! Guess what, they shot lights outs. I can't tell you why, it goes against eveything we strive for in precision barrel chambering. Makes me wonder why I spend so much time dialing in and cutting chambers. I will keep doing it the way I do though. theres many ways to skin a cat, find the way that works for you......
Casey
Casey
Be careful speaking in absolutes.
That is not the case with all barrel manufacturers.
Some makers do things in a different sequence than others.
Krieger does in fact contour and handle all O.D. work prior to the rifling being cut.
The first step for them is to Cryo treat the blanks before they are even deep hole drilled and the last thing they do is rifle the bore and lap.
They do this to help ensure there are no dimensional changes during the rifling process and also help produce the minimum amount of stress in the barrel possible.
Some button rifled barrels may have the rifling formed prior to contouring the O.D. for least expense, etc. but not all.
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Thank You Terry, obviously, I was not aware of that. I appreciate the information.
I don't have a lot of time this morning, but I will come back later today/this weekend and further respond to this post and your other post about my comment on "windage"/timing.
My primary motivation in all of this is to try and discourage anyone from thinking that just because the bore exits either end of the barrel and is "non-concentric", relative to the exterior/OD/contour, that the bore (or the barrel, for that matter) is in any way "deficient".
Thank you.
Looking forward to you expanding on that to explain what you mean.
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Hi Terry,
OK, let me give this a go;
Couple of things I'd like to establish and they are just my opinion,
1. Today's barrel manufacturers are top notch and I think the chances of getting a bad barrel are pretty remote. As with all things in life, it can happen, but the vast majority of barrels that leave a given manufacturers building are very good.
2. From my point of view, between the bore being "straight" and the contour being "straight", I will always choose the bore being straight, if I can choose only one. In fact, I personally don't really concern myself about much in regard to the contour, other than what I will mention below.
3. In a perect world, the bore would be exactly straight, with 00.00000" of deviation over it's entire length. In a less than perfect world, that is not realistic. So, while the manufacturers do great jobs, there will always be some (very ?) minor variation in straightess of the bore.
4. Because of number 3 above, I would assume that either the variation of straightness of the bore is either simply banana shaped, or it is pigtail shaped over the entire length of the barrel. Because I do not have sophisticated equipment to measure bore straightness/deviation, I cannot measure it. If the equipment does exist, I probably cannot afford it.
5. Because of number 4 above, I have to make the practical decision that what little deviation in bore straightness that "might" exist, I choose to assume it is banana shaped. I'll also call it being concave. Of course, that depends on one's perspective.....pun intended.
6. Because of number(s) 3, 4 and 5 above, regardless of the variation in bore straightnes, or the type (banana or pigtail), there is nothing I can do to correct the deviation and make the bore perfectly stright.
7. So, "if" there is deviation in the straightness of the bore (and there probably is....) it is probably very minor and.....there is nothing I can do to "fix" it.
Assuming a banana shape, I always spend just a little more time in setting up/dialing in the blank in the 4 jaw on the work side and the 4 screw spider on the back/non-work side of the headstock to find the furthest point of the OD of the blank, in comparison to the bore. I use alignment rods in the bore at both ends and Mitutoyo .0001" res dial indicators.
This tells me the "thickest" point, which would be the "convex" side of the curvature of the banana shape. I always clock that point to the 6 O'clock position and the thinnest point to the 12:00 O'clock position. As you know, the way to clock the timing of the barrel is in cutting the trunion/shoulder to get everything to line up where you want it. That way, if there is indeed a banana shaped deviation of bore straightness, it can be compensated for with a simple elevation adjustment on a scope.
OK, having said all that, "if" there is indeed a banana shape to the bore, what I want to avoid is inadvertently clocking it (the banana/concave shape) to say, 9:00 or 3:00 O'Clock. If that happens, windage adjustments will have to be made. And with targets at increasingly greater distances, larger windage adjustments will have to be made. If I clock the concave portion to 12:00 O'Clock (and I managed to do it "perfectly"), correction is just a normal part of elevation adjustments with varying distances, which is a normal part of "doing business".
I am not convinced that any possible deviations in bore straightness are significant enough that I really need to worry about them. However, like I said earlier, compensating for the "possibility" adds maybe 10% more time to the setup. To me, it's worth the extra time to do it.
And, having thought a little more on this, I do not think that if the contour (OD) at the muzzle is "out of concentricty" in relation to the bore, that in any way indicates whether the bore is perfectly straight or not. That is the point that I have been trying to make to others here. In other words, don't look at the muzzle of a Kreiger or Bartlein barrel and assume that because there is 10 thou of variation between the bore and contour that there is "something" wrong with it. That is in no way an indication of bore straightness.
Very much looking forward to your feedback.
What if the bore follows more of a M shaped path? Or a N? Not a V?
Several people have turned a barrel parallel between centers, scribed a line down it, parted it every inch and then measured the wall thickness in relation to the scribed line of each of the pieces. Obviously this is destructive mapping, and can not be done for every barrel, but it kind of tosses out the “banana” bore idea. The deviation is far more random from the examples I saw.
Several people have turned a barrel parallel between centers, scribed a line down it, parted it every inch and then measured the wall thickness in relation to the scribed line of each of the pieces. Obviously this is destructive mapping, and can not be done for every barrel, but it kind of tosses out the “banana” bore idea. The deviation is far more random from the examples I saw.
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Hmmm...interesting concept. But, like I said, I can’t correct it. Because of that, I have to make some assumptions.
If, in the destructive testing you mention above, measurement of each sample revealed variations to indicate an “M, N, or V” shape, then yes, of course, that would “toss out” the banana bore idea. Please don’t misunderstand, I’m not saying it is banana shaped. If variation does exist, because I can’t measure it, I don’t know what shape it “is”.
In thinking even further about it, could a credible argument be made that the only portion of the barrel that really matters is the last two or so inches at the muzzle ? I’m not going to try that one on for size........
I have no data nor major ideas to add, but I do know from my experience there is definitely some variation between bore and barrel concentricity in most barrels. It varies from barely measurable to very noticeable. How much it matters is the debatable part and I can’t say that there’s a correlation, but it does exist.
Hi Terry,
OK, let me give this a go;
Couple of things I'd like to establish and they are just my opinion,
1. Today's barrel manufacturers are top notch and I think the chances of getting a bad barrel are pretty remote. As with all things in life, it can happen, but the vast majority of barrels that leave a given manufacturers building are very good.
2. From my point of view, between the bore being "straight" and the contour being "straight", I will always choose the bore being straight, if I can choose only one. In fact, I personally don't really concern myself about much in regard to the contour, other than what I will mention below.
3. In a perect world, the bore would be exactly straight, with 00.00000" of deviation over it's entire length. In a less than perfect world, that is not realistic. So, while the manufacturers do great jobs, there will always be some (very ?) minor variation in straightess of the bore.
4. Because of number 3 above, I would assume that either the variation of straightness of the bore is either simply banana shaped, or it is pigtail shaped over the entire length of the barrel. Because I do not have sophisticated equipment to measure bore straightness/deviation, I cannot measure it. If the equipment does exist, I probably cannot afford it.
5. Because of number 4 above, I have to make the practical decision that what little deviation in bore straightness that "might" exist, I choose to assume it is banana shaped. I'll also call it being concave. Of course, that depends on one's perspective.....pun intended.
6. Because of number(s) 3, 4 and 5 above, regardless of the variation in bore straightnes, or the type (banana or pigtail), there is nothing I can do to correct the deviation and make the bore perfectly stright.
7. So, "if" there is deviation in the straightness of the bore (and there probably is....) it is probably very minor and.....there is nothing I can do to "fix" it.
Assuming a banana shape, I always spend just a little more time in setting up/dialing in the blank in the 4 jaw on the work side and the 4 screw spider on the back/non-work side of the headstock to find the furthest point of the OD of the blank, in comparison to the bore. I use alignment rods in the bore at both ends and Mitutoyo .0001" res dial indicators.
This tells me the "thickest" point, which would be the "convex" side of the curvature of the banana shape. I always clock that point to the 6 O'clock position and the thinnest point to the 12:00 O'clock position. As you know, the way to clock the timing of the barrel is in cutting the trunion/shoulder to get everything to line up where you want it. That way, if there is indeed a banana shaped deviation of bore straightness, it can be compensated for with a simple elevation adjustment on a scope.
OK, having said all that, "if" there is indeed a banana shape to the bore, what I want to avoid is inadvertently clocking it (the banana/concave shape) to say, 9:00 or 3:00 O'Clock. If that happens, windage adjustments will have to be made. And with targets at increasingly greater distances, larger windage adjustments will have to be made. If I clock the concave portion to 12:00 O'Clock (and I managed to do it "perfectly"), correction is just a normal part of elevation adjustments with varying distances, which is a normal part of "doing business".
I am not convinced that any possible deviations in bore straightness are significant enough that I really need to worry about them. However, like I said earlier, compensating for the "possibility" adds maybe 10% more time to the setup. To me, it's worth the extra time to do it.
And, having thought a little more on this, I do not think that if the contour (OD) at the muzzle is "out of concentricty" in relation to the bore, that in any way indicates whether the bore is perfectly straight or not. That is the point that I have been trying to make to others here. In other words, don't look at the muzzle of a Kreiger or Bartlein barrel and assume that because there is 10 thou of variation between the bore and contour that there is "something" wrong with it. That is in no way an indication of bore straightness.
Very much looking forward to your feedback.
Holy cow! Took me a while to read through your reply.
.....but you still did not explain what i was referring to.
Please read what I underlined in the quote of your original statement. .....
That is all I was asking for you to explain.
This whole chambering, barrel spinning, curvy bore stuff is amazing. All new to me so keep it simple.
./
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Companies like Weatherby used to test-fire their rifles with three rounds at 100 yards and include the test target with the gun. I have one of these guns. Wouldn't that catch any curvature or "out of round" issues? Incidentally, the three-round test target on this gun almost looks like two rounds, and not three. Not bad for an off-the-rack gun. And, with Weatherby ammo at that.
Attachments
Throw a scope on and zero it.
Maybe you have to dial in some semi significant windage to zero it, maybe you have less or more elevation afterwards than you expected.
It won’t effect how it groups for three of five shots.
I think I understand the mindset of Timing a bbl as I have been down that road
Theoretically, the bore of the bbl does not have to be in the center of the blank. Offset to L or R would be PIA, but .1” to .3” offset vertical would not be an issue. I am talking true bore, not.1” plus on breach to .1” neg on muzzle
The last rifle I had made, my buddy put the blank in lathe and got centered up ready to cut chamber. I bought a 264 Range Rod. We then inserted in muzzle. Indicated the “high” side, he redid setup with mark at 12 O’clock
Now, he cut the chamber with a floating reamer holder. He uses that because there is no such thing as a perfect settup. It can move w settup or bore is not perfect cl to exterior of bbl.
After chamber cut, threaded to screw in action, the mark was at 10.30, not 12 Oclock
Put TPS rail and rings on it, NF scope
Rifle will hold sub 1/2moa group all day at 100 yds
Now the mark ended up at 10:30. I zeroed the scope at 100yds. At 600yds does it “make” the bullet drift towards towards 10:30? No
This is where so many variable come into play. How good are you? Wind. Barometric pressure. I live in SW Ark, humidity. Different lds induce different harmonics in bbl
There is nothing wring with “timing” a bbl to 12 Oclock. Does it actually help? It sure doesnt hurt, but you cant prove it actuall helps either, with all the other variables figured in.
TC built me 308 20 yrs ago. Most boringly accurate rifle I have owned. Obviously He didnt time bbl on it and it was a Lazer
By 2 bits. Krw
Theoretically, the bore of the bbl does not have to be in the center of the blank. Offset to L or R would be PIA, but .1” to .3” offset vertical would not be an issue. I am talking true bore, not.1” plus on breach to .1” neg on muzzle
The last rifle I had made, my buddy put the blank in lathe and got centered up ready to cut chamber. I bought a 264 Range Rod. We then inserted in muzzle. Indicated the “high” side, he redid setup with mark at 12 O’clock
Now, he cut the chamber with a floating reamer holder. He uses that because there is no such thing as a perfect settup. It can move w settup or bore is not perfect cl to exterior of bbl.
After chamber cut, threaded to screw in action, the mark was at 10.30, not 12 Oclock
Put TPS rail and rings on it, NF scope
Rifle will hold sub 1/2moa group all day at 100 yds
Now the mark ended up at 10:30. I zeroed the scope at 100yds. At 600yds does it “make” the bullet drift towards towards 10:30? No
This is where so many variable come into play. How good are you? Wind. Barometric pressure. I live in SW Ark, humidity. Different lds induce different harmonics in bbl
There is nothing wring with “timing” a bbl to 12 Oclock. Does it actually help? It sure doesnt hurt, but you cant prove it actuall helps either, with all the other variables figured in.
TC built me 308 20 yrs ago. Most boringly accurate rifle I have owned. Obviously He didnt time bbl on it and it was a Lazer
By 2 bits. Krw
Would you mind passing the salt ? This crow is a little bland.....The manufacturing sequence Brux uses.
Vide
www.bruxbarrels.com
I'm not a gunsmith, just a reader, but it doesn't look to me that the Brux sequence shown is a lot different than what you said. Step three is drilling, then step four is final contouring.
Now this is making me want to go to a related but new subject -
How are most factory rifle barrels made? Are they drilled, or are they forged over a mandrel?
Maybe I'd better do a new search and/or new thread for this one . . .
How are most factory rifle barrels made? Are they drilled, or are they forged over a mandrel?
Maybe I'd better do a new search and/or new thread for this one . . .
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If the curvature of the bore happens to exit with a bias toward 3 o'clock or 9 o'clock please explain what you mean by increased windage compensation being slaved to any increase in distance?
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Hi Terry,
This has been a bit of a rollercoaster for me. After I had time to think about everything yesterday, particularly this, I finally figured out that was your original question. My choice of words to describe this were not only poorly chosen, but they were indeed wrong, I now believe.
In the interest of me not wanting to write a book and no one else wanting to read one, I believe the correct statement would be; (as an example) “a requirement of 1 mils of correction due to bore misalignment at 100 yards would be the same requirement for 1 mil correction for bore misalignment at 1,000 yards”.
In other words, even “if” a bullet is following a curve in the bore, it will not continue on a curved (horizontal, 3:00 or 9:00 o’clock misalignment) path once it exits the muzzle, it will travel in a straight line. (in spite of what Angelina Jolie did in one of her movies......).
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Exactly.
Once you zero your windage at 100, you will have zeroed it for all distances.
You took the time to write very, very in depth and detailed answers on multiple posts in this thread yet there were a few issues with the info.
I just wanted you to think a little harder at your explanations and get the chance to change your stance, .... if for no other reason than for any "new to the game" rifle enthusiasts that may visit here, read your posts and not get wrapped around the axle for a non existent problem.
Thanks and be safe.
T.
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Hi Terry,
Thanks once again for the feedback, appreciated.
You know, the hell of it is, is that I have known that all along. What I don't know is how that dumpster fire of a statement got from my brain to my keypad and the "Post" key got pushed by me.
Saturday afternoon, I was driving around up in the mountains and I was thinking about it. All of a sudden, it hit me. I understood what (and more importantly "why") you were asking. It was such a simple thing, but I had the blinders cranked down pretty tight.
I completely understand your motives/methods and agree with what you did. Thank You for that.
So, on to "bigger and better" things;
If I understand you correctly, you are not concerned about possible "mis-alignment", because you know that wherever (clock position) the error winds up, it's just a "one time" windage (or elevation) adjustment ? And, I assume that most people would not even know they are compensating for any possible error while going through the process of sighting in.
And, second/semi-related question; If you were to notice "a bore (muzzle) that is out of concentricity with the contour/OD", do you, or would you do anything about it ? (I italicized the statement because I still feel very strongly that the focus should be primarily on the bore and secondarily on the contour/OD. The bore is the point that everything else should be referenced to).
Thanks again for everything
If I understand you correctly, you are not concerned about possible "mis-alignment", because you know that wherever (clock position) the error winds up, it's just a "one time" windage (or elevation) adjustment ? And, I assume that most people would not even know they are compensating for any possible error while going through the process of sighting in.
And, second/semi-related question; If you were to notice "a bore (muzzle) that is out of concentricity with the contour/OD", do you, or would you do anything about it ? (I italicized the statement because I still feel very strongly that the focus should be primarily on the bore and secondarily on the contour/OD. The bore is the point that everything else should be referenced to).
Thanks again for everything
I am not tracking for sure with what you are asking on your first question.
If you are asking whether I am concerned about what direction any bore curvature may be at the muzzle, the answer is yes. I will clock the breech work to time the muzzle run out to 12 o'clock. Easy to do and just extra insurance to be sure the user isn't eating up windage un-necessarily.
That being said, I have repeatedly ran into a high percentage of Kriegers that have so little bore runout at the muzzle that I will not mark and slave the breech work to that direction.
When I typically bring a group of completed rifles to the range for control groups, I will drop a scope on Rifle #1, confirm I'm close with bore sighting, fire first shots on paper and then tweak the zero for that rifle to shoot 3 consecutive groups on the test target. Almost without fail, I can move the scope to the next rifle and be on paper (8.5x11" sheet of 100# index) so I can just jump to a fine tuned zero for that rifle. Rinse and repeat. The consistency makes me feel more confident in the processes being used.
Your second question: I absolutely do not sweat any difference between the OD and bore being concentric. I basically always ignore the O.D. except when touching off a cutting tool prior to making chips.
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I am not tracking for sure with what you are asking on your first question.
If you are asking whether I am concerned about what direction any bore curvature may be at the muzzle, the answer is yes. I will clock the breech work to time the muzzle run out to 12 o'clock. Easy to do and just extra insurance to be sure the user isn't eating up windage un-necessarily.
Yes, that was the question. Yes, easy to do, that is what I do as well. Same concern about eating up windage.
That being said, I have repeatedly ran into a high percentage of Kriegers that have so little bore runout at the muzzle that I will not mark and slave the breech work to that direction.
When I typically bring a group of completed rifles to the range for control groups, I will drop a scope on Rifle #1, confirm I'm close with bore sighting, fire first shots on paper and then tweak the zero for that rifle to shoot 3 consecutive groups on the test target. Almost without fail, I can move the scope to the next rifle and be on paper (8.5x11" sheet of 100# index) so I can just jump to a fine tuned zero for that rifle. Rinse and repeat. The consistency makes me feel more confident in the processes being used.
And, actions being so consistent as what they are today, certainly helps in that regard.
Your second question: I absolutely do not sweat any difference between the OD and bore being concentric. I basically always ignore the O.D. except when touching off a cutting tool prior to making chips.
That's what I figured. What is the worst example you have seen in terms of the difference between the OD and bore being concentric ? I have a couple of Bartlein HV blanks out in the shop that I'm going to go measure for grins. Pretty much no matter how much difference there might be, it isn't going to convince me there "could" be a problem, I'm just curious.
Thanks again, be well
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"What is the worst example you have seen in terms of the difference between the OD and bore being concentric ? I have a couple of Bartlein HV blanks out in the shop that I'm going to go measure for grins. Pretty much no matter how much difference there might be, it isn't going to convince me there "could" be a problem, I'm just curious "
A few years ago, I cut some button rifled barrels for a project as a favor. All from one maker and one lot of manufacture. The blanks were 27". I was cutting them to 16.5" and threading the muzzles for suppressor adapters. Once the excess front piece was parted off, the bore/O.D. difference at the new muzzle was over 0.075" on 4 or 5 of them.
On anything I normally run these days, I never measure the difference even if it is visible. The Kriegers, Bartleins, Hawk Hills and similar are stress free and super well behaved. I watch for it but if it looks reasonable (100% do) I don't even worry about it. All are lasers when handled correctly and show no issues whether cold, heated up, with or without suppressors, etc.
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A few years ago, I cut some button rifled barrels for a project as a favor. All from one maker and one lot of manufacture. The blanks were 27". I was cutting them to 16.5" and threading the muzzles for suppressor adapters. Once the excess front piece was parted off, the bore/O.D. difference at the new muzzle was over 0.075" on 4 or 5 of them.
On anything I normally run these days, I never measure the difference even if it is visible. The Kriegers, Bartleins, Hawk Hills and similar are stress free and super well behaved. I watch for it but if it looks reasonable (100% do) I don't even worry about it. All are lasers when handled correctly and show no issues whether cold, heated up, with or without suppressors, etc.
./
Years ago a close friend was gassing up some ammo in preparation for a Palma Team practice in Sacramento. I noticed a number of things he did that compelled me to inquire about later on the flight. "Basically, anything I can do to improve quality encourages better consistency."
Fair enough and it's difficult to argue with a National Champion. (David Karcher)
So, taking that advice and applying it here:
"Timing" a barrel so that the natural curve points in a particular direction requires very little effort to do and it has zero consequence. It can be debated till the end of time as to its true influence on performance. The reality is that isn't what truly matters. If you as the person using the rifle believe that it helps, then doing so will elevate your confidence level in the equipment.
Overcoming that mental giant is a big part of shooting well.
How I do this is pretty silly stupid:
Chuck up barrel in a 3 jaw holding onto the cylinder portion while allowing the muzzle end to hang in space. Turn on the lathe at low RPM and grab a Sharpie marker. I rest my hand on the compound and slowly move towards the muzzle at a right angle until the tip of the Sharpie makes a swipe on it. Now stop the spindle and reverse it. Repeat the same thing again, mark the barrel a 2nd time. Shut off the machine, remove the stick, and mark the "top dead center" between the two swipes. You now have your high spot.
30 seconds of your life you'll never get back.
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