Barrel Chambering for Long Range

J

Jay Cutright

New member
This all started as a reply to Skeet Lees barrel chambering thread/question and I decided to post it as a new thread.
When I first started chambering my own barrels I had a cut blank with a .237 bore made to finish at 32". I chambered it using the Gordy method crowned it at 29" and shot it in competition for the rest of the year.
This barrel was the best shooting barrel I had to date and it was out every bit of .060 at the muzzle. I measured the runout when I indexed the muzzle to shoot up or at 12 O clock.
I could barely get my scope to 0 at 100 yards.
The problem was I never really saw any outstanding groups at 200 yards, I always had some flippers in the group and just assumed I couldn't read the condition well enough at close range to dope the group into one hole.
I have learned a lot these past couple years, and recently pulled that barrel out of my barrel cabinet and sawed it off and dialed it in to run true at the lead and muzzle. I then drilled & bored it true & rechambered it with the exact same reamer & set the headspace right back to where it still worked with the same old brass and die adjustment.
I have never owned a long range barrel that shoots so well at 100 & 200 yards. This thing is so predictable & it rides the bags so well that I can completely free recoil it with my head up watching the flaggs and never flip a shot. I think some of these old timers are onto something here with these short range rifles needing the muzzle directly in line with the rest of the rifle instead of indexed to shoot up or down. I have now shot the smallest groups I have ever shot at my 200 yd range.
The thing that puzzles me is I have yet to shoot a group at 600 yd to make me think it is worth taking to a match.
 
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Well, there ya go, sticking a bunch of data into a perfectly subjective discussion! Seriously, your experience with that barrel is really interesting. I had two thoughts sitting here drinking my first cup of coffee:
  1. It occurrs to me that having the scope so close to the end of it's elevation range with the barrel indexed up might be part of the way the rifle system performed like it did at short range. To know how much elevation was added by the barrel isn't easy to figure out. The 0.060" is only part of the story. The direction the bore was pointing in the barrel is the other part.
  2. The dynamics of the barrel/rifle might change as a result of the barrel orientation. The forces might be less concentric and cause the vibration to be more consistant, or smaller.
What I don't understand is what the physics are that cause a barrel to shoot with fliers at short range but not long range. And near perfectly at short range but not long range.

Fitch
 
Jay Cutright said:
This all started as a reply to Skeet Lees barrel chambering thread/question and I decided to post it as a new thread.
When I first started chambering my own barrels I had a cut blank with a .237 bore made to finish at 32". I chambered it using the Gordy method crowned it at 29" and shot it in competition for the rest of the year.
This barrel was the best shooting barrel I had to date and it was out every bit of .060 at the muzzle. I measured the runout when I indexed the muzzle to shoot up or at 12 O clock.



.
Click to expand...
Jay, those of us who know you know you are a very competitive and competent long range shooter. That feeling expressed, how do your current barrels perform and what method do you use now, especially the one you shot in LG at St Louis in the 2010 Nationals?

I'm not doubting the wobble/clock method doesn't produce competitive shooting barrels. Its just that I wouldn't do mine that way mainly that I want the gun and the muzzle pointing in the same general area.
 
Two thoughts, both a bit irreverent:

The first is when you cut material off the barrel, you changed it. Now if we could make this happen every time, we'd learn something, but I think what happens is, this sort of result occurs, but not often. There is nothing to check for, because we don't know what to look for.

Remember Tony Boyer and hummer barrels? For Mr. Boyer, a "hummer" wasn't a barrel that shot really small, it was a barrel that seemed to shoot through the wind. The pixel pushers have changed how most use the word. In an attempt to find out why some barrels were hummers, Ed Shilen very carefully examined some on Tony's hummer barrels. He couldn't find any physical properties that were different from, non-hummers. Which isn't to say there aren't any, just that we don't yet know what they might be.

The second goes along the same vein. I'm not suggesting it is true of you, but it is true of many. A well-tuned rifle shoots through things. Leakers happen far less often. Like "hummer", it is sort of a backwards definition. The point to all of us is that if we have a barrel that shoot zeros at 6:30 am but not the rest of the day, we don't have a tuned rifle, we have one sensitive to some conditions. How do I know this? Occasionally I get a rifle in perfect tune. Shots that should have gone out, or missed the X, or whatever, just don't. I don't mean being in in a "zone" as a shooter, that's when you don't make any mistakes. I bring that off every five years or so. No, the tuned rifle lets you get away with some small mistakes, and most of us can bring that off more often than every five years.

* * *

Well, none of this explains what you've reported. It just adds noise. But that noise needs to be there, because it is real too, and has to be accounted for.
 
I have heard stories of shooters back in the early days, (for many, that is '70's and 80's), taking barrels and cutting about 1/8 inch from the crown untill it shot well.

Many of us have had a great barrel, or stumbled onto a great tune, that made us invinsible at the firing line. Regardless of what we did, the bullets all wanted to follow one another down the same path.

Jay, some years ago, I thought I would use all of my machinist skills to ascertain why one barrel would shoot great, and another "just good". I gave up, some that I figured would be screamers were not worth the effort.

You obviously changed something in the barrels personality. The big question is "what"? And, why did that seem to make the barrel act different at different distances?

I never could quite grasp the concept of a barrel shooting better MOA at long distance than short. It would seem to me that once that bullet is traveling off the beaten path, things will continue to get larger as it progresses to longer distances, barring devine intervention or blind luck.

In another thread, I alluded to a top Gulf Coast Region Shooter who used method of chambering that involved truing up the first inches of the chamber end, and not woryying about the muzzle end. This is opposed to my method. I feel like our Rifles are equal in capability, many times at practice I can shoot smaller groups. But, he usually bests me at matches because, simply put, he is a better Benchrest Shooter under Match Conditions than I am.......jackie
 
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JerrySharrett said:
Jay, those of us who know you know you are a very competitive and competent long range shooter. That feeling expressed, how do your current barrels perform and what method do you use now, especially the one you shot in LG at St Louis in the 2010 Nationals?

I'm not doubting the wobble/clock method doesn't produce competitive shooting barrels. Its just that I wouldn't do mine that way mainly that I want the gun and the muzzle pointing in the same general area.
Click to expand...
The barrel I used at St. Louis last fall was chambered using the Gritters method with the exception being I used a tapered/piloted range rod instead of the long piloted rod like Gordy uses.
I'm beginning to think that there is a better way for long range barrels to be chambered and that it isn't the same as what produces a good group or score barrel for the traditional 100 200 & 300 yard rifle. These are thoughts based on the outcome of this last experiment and the fact that Gordys barrels always kick ass every year at the 1000yd Nationals.
I have a 30BR barrel that I chambered using the Gordy method, it has some potential but it's just not there for me. I'm going to cut it off 1" rechamber it using a method more consistant with what you and Jackie do, as I did the long range barrel in the opening statement, and see if it comes together for me as I think it will.
 
In long range our rifles are shooting up hill, with a barrel chambered the "Gordy" method and indexed to shoot at 12 o clock the barrel is shooting uphill too. I'm just saying that maybe this bucks the theory that works for the short range rifles that need to have the muzzle directly inline with the rest of the rifle.
I'm saying this because for me the short range barrels that I have done with the muzzle centered have all shot well for there intended purpose but the one I chambered using "Gordys" theory doesn't do so well and now for more thinking I have a long range barrel rechambered in a manner more consistant with what works for short range that doesn't shoot long range as good as it once did.
I'm looking to get busy on this 30BR barrel soon so I can see if this will be the turning point where I use one theory for a short range barrel and another for a long range barrel.
 
Now lets throw rifle balance into the equation as well. I recently installed a Hunter class tapered barrel on my main sporter rifle that has always had LV barrel contours on it. Both contours of barrels weigh about the same at 5 lbs 2 to 4 ounces with 22" barrels on either contour of barrel. With the hunter class taper on the rifle, the rifle seems to recoil into my shoulder more than it did with the LV taper barrels enough by the end of a days shooting my shoulder was getting sore which it never did with a LV taper barrel. Balance is the only thing that I can see that would cause the problem. The hunter taper barrel puts more of the weight of the barrel closer to the receiver while with the LV taper barrel moves it farther away from the receiver. The barrel shoots very well, but it's either going to come off and be replaced with a LV taper barrel or it's going to have a tuner installed to move the weight farther forward. I'll probably flute the barrel and put a tuner on it to redistribute the balance of the rifle. I once installed a barrel on this rifle that was about 8 ounces under the 5 lbs 4 ounces of barrel that I normally used on the rifle. I added 8 ounces of weight in the butt to bring it up to weight. The rifle handled completely differently off the bags and seemed to jump more in the bag setup. It no longer would shoot free recoil. Changing back to a 5 lb 4 ounce LV taper barrel and it went back to recoiling the way it always had. I think that how the balance of a rifle is setup is more critical than what most of us realize. It may not be so easy to tell when it's right, but it sure is easy to tell when it's not right.
 
Jay,

I already replied to your comments on the other thread before i had a chance to read some of these other very valid comments.

In short, the barrel maker probably has a fair bit to answer for with the amount of bow in the bore, as you mentioned over 0.060" TIR at the muzzle when you indexed it.

'Frozen scopes' used by some BR shooters, can/may be a concern with regards to muzzle orientation?

The bullet does need the best start into the rifling as straight as possible, i think we can all agree on that.

A good thread fit and chamber job as aligned with the bore as best possible, preferrably in one set-up, is also something I hope we can agree on.

But, fliers on a bowed bore with an indexed/offset muzzle could well be due to velocity variations? Maybe more so than with a 'centered muzzle' ?

I also think someone mentioned barrel harmonics?

As a bizzare side issue which may relate to barrel vibrations/harmonics, recently I deliberately fitted a really bowed-bore barrel to a hunting rifle as an experiment/project rifle (muzzle indexed up). Then fitted a silencer to it (legal in NZ). At 100 meters, the (.30BR) rifle shoots very accurately for purpose, with the barrel free-floating and silencer fitted. When we then removed the silencer and testfired again, the rifle then groups 4" low and 1.5" to the left. This is totally bizzare, as usually when a 1.5lbs over-barrel silencer is fitted to a sporting rifle the weight pulling the barrel down usually causes a silenced rifle to shoot lower than an un-silenced (or unweighted) barrel.

(The silencer was correctly aligned with the barrel with no side-tension at all.)

Dean.


Dean.
 
Dean



Dean, IMO this is a flexing "tune" thing. I'll betcha' that when you work up loads using the suppressor your groups walk up and down a bit eh????

al
 
As some here know, I have been playing with a scope tester for a few years now. It is similar to the one that mounts two
scopes on a single rifle, however mine mounts two scopes on a fabricated steel arangement which sits on the bench. In the first
generation, Both pairs of mounts were parallel, but the scope used as control was frozen but crosshairs were not in the physical
center. Thinking I would simply adjust windage and elevation to co-ordinate with the frozen control scope. Way to many scopes
were failing and the cause was eventually found. Many of those that failed have been retested with success. What I found was
that any time a scope is adjusted very far from its physical center, it is operating at a great disadvantage. It may be that
springs are overly compressed or relaxed to far, then it may also be that the adjustments don't contact where they should. By
simply relocating the mounts for the control scope so the scope in question was operating in the center of its adjustments, the
failure rate was far less. Tony explains this in his book quite well.
I might add that some factory rifles just won't let you position a scope and allow the scope to work in the center of its
adjustments. Custom actions really shine in this department, as the inside and outside agree. Installing a barrel that does not
allow the scope to function in its center for what ever reason can't help this problem
 
Mike Bryant said:
Now lets throw rifle balance into the equation as well. . . . I think that how the balance of a rifle is setup is more critical than what most of us realize. It may not be so easy to tell when it's right, but it sure is easy to tell when it's not right.
Click to expand...

Mike, you're probably right. I seem to remember that when Varmint Al was modeling things for the tuner discussion, he mentioned that the firing made the forearm lift, perhaps so much that it no longer remained in contact with the front bag.

I can't do that kind of modelling, but with any new rifle, I test out various positions of the front rest, and the effect on accuracy. Quite often, there are some.

And if a rifle pounds me like your .30 BR but shoots best that way, I'll put up with it. I have a long-range chambering similar to a .300 Norma Magnum I shoot free recoil, because it shoots best that way. I understand that this willingness stems in part because I don't have your skill to re-tailor the rifle, something for us all to think about!
 
Bob Kingsbury said:
As some here know, I have been playing with a scope tester for a few years now. It is similar to the one that mounts two
scopes on a single rifle, however mine mounts two scopes on a fabricated steel arangement which sits on the bench. In the first
generation, Both pairs of mounts were parallel, but the scope used as control was frozen but crosshairs were not in the physical
center. Thinking I would simply adjust windage and elevation to co-ordinate with the frozen control scope. Way to many scopes
were failing and the cause was eventually found. Many of those that failed have been retested with success. What I found was
that any time a scope is adjusted very far from its physical center, it is operating at a great disadvantage. It may be that
springs are overly compressed or relaxed to far, then it may also be that the adjustments don't contact where they should. By
simply relocating the mounts for the control scope so the scope in question was operating in the center of its adjustments, the
failure rate was far less. Tony explains this in his book quite well.
I might add that some factory rifles just won't let you position a scope and allow the scope to work in the center of its
adjustments. Custom actions really shine in this department, as the inside and outside agree. Installing a barrel that does not
allow the scope to function in its center for what ever reason can't help this problem
Click to expand...

Hi Bob, I think that Jay forgot to mention on this thread here that he was shooting with a 20 MOA base for long range as per his usual set-up, but when he fitted a zero MOA base he could adjust the scope in at short range OK. I noted he added this data as a belated addition to his earlier comment on the other thread about chambering.....

Thanks for your comments and all the hard work you have done with the scope experiments!

Cheers,

Dean.
 
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