Seems like when I use my grizzly rod I get some excessive play on my idicator that doesn't always make since. The sides of the chuck can be reading true but there may be one side were the indicator willl jump around. Almost seems like a tall land on a cut barrel. Anyone else see excessive movement while using the grizzly or gordy rods? Lee
Gunsmithing Different ways to indicate and thread/chamber a barrel
- Thread starter McLarenross
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Lee,
I've seen tall lands, or more commonly, a groove that's cut a couple tenths deeper than the others. Usually I find it when I chase my tail for a while trying to get the thing dialed and when I just get annoyed and put a bore scope in there I can see the ever-so-slight difference in depth on the groove.
I've seen tall lands, or more commonly, a groove that's cut a couple tenths deeper than the others. Usually I find it when I chase my tail for a while trying to get the thing dialed and when I just get annoyed and put a bore scope in there I can see the ever-so-slight difference in depth on the groove.
Here is a short vid of a 6x47 Lapua barrel I did Saturday, prebored a small bit and then used the DI to zero it. Before anyone says anything about the 3 jaw, it's a Set-tru, I zero the bore by moving the chuck. There is a spider on the other end of the spindle, I get the muzzle end close first, before even tightening the chuck. I find that how the chuck grips the barrel is affected by how true the aft end is, regardless of how big and meaty the chuck jaws are. Looking at the chamber when it's done, everything is perfectly concentric, and they shoot better, brass lasts longer ( most of this is for BR rifles, been playing with that a lot lately, learning a lot ).
One very nice additional bit of info - you get a lot of insight to barrels doing this. You can see every little imperfection, every time a land is clocked differently ( esp on 4 groove barrels ), every high and low groove. Sometimes I have to move in a bit more to get a good place to read from, and I now try to cut off at least 2 inches from every barrel, particularly on the muzzle end, most of the funky part of the breech end becomes chamber.
One very nice additional bit of info - you get a lot of insight to barrels doing this. You can see every little imperfection, every time a land is clocked differently ( esp on 4 groove barrels ), every high and low groove. Sometimes I have to move in a bit more to get a good place to read from, and I now try to cut off at least 2 inches from every barrel, particularly on the muzzle end, most of the funky part of the breech end becomes chamber.
So if your just using an indicator in the bore to dial in what do you do about high and low spots? I am seeing a lot of this with a certain 4 groove cut barrel make here as of late. Also do you indicate jist the throat or the hole chamber area? Lee
Lee,
I've found it three times, I sent one back as it was almost 0.001" deeper in 1 groove and the barrel maker was fantastic about it. "Not sure how it got out the door, but we'll have a new one to you in a week or less". The other two I was just working on a friend's rifle and he was in a hurry to get it done. His response "eh.. I was going to chamber it with a hand drill, let's get this going".
Those two rifles still shot really really well, he's pretty hard on barrels with a 243 so they didn't last long. The difference in depth was less than 1/2 thou on each and at the end of the day it really didn't matter for field rifles.
I've found it three times, I sent one back as it was almost 0.001" deeper in 1 groove and the barrel maker was fantastic about it. "Not sure how it got out the door, but we'll have a new one to you in a week or less". The other two I was just working on a friend's rifle and he was in a hurry to get it done. His response "eh.. I was going to chamber it with a hand drill, let's get this going".
Those two rifles still shot really really well, he's pretty hard on barrels with a 243 so they didn't last long. The difference in depth was less than 1/2 thou on each and at the end of the day it really didn't matter for field rifles.
If I can, I try to indicate about where the neck will be, or as close to it as possible. Not possible on big things like 338 Lapua. Chads method with the probe and wieght probably better for that, but have had good success with getting close.
On the irregular stuff, either move forward or aft a little big, seems to help a lot, kinda tells me it is a localized issue, BUT .... not something I want in the throat! If one groove is a bit deeper, on that 4 groove for instance, I just spread it out between the two sides. For instance, I number my adjustment screws 1-4, 1 and 3 have equal runout, 2-4 have equal runout. All four may not be the same, but that would be the preferred endpoint.
If the grooves are off a bit in clocking, same thing, move in a bit sometimes makes it much less so. Rifles seem to shoot OK even with grooves out of precise clock position anyway, this may not be an issue. I'd be more than a little curious to hear others thoughts on that, I am thinking to get a borescope to check out the local conditions next time I see this Might just be a burr, or irregularity, rather than a clocking issue, knowing how cut rifled barrels are made.
Doing coupling alignment on big power turbines for years, was a very good training ground for this. It's one reason I use this method,
it is simple for me to remember. If you can do rim and face readings on a coupling, this is easy.
I had not through to do this, but I like that idea a lot, thanks for posting it. Next time I come across one that's got a notable difference I'm going to try this and see how things go.
Ok sounds like a resonable idea. Now what about cutting the chamber? Do you guys use the reamer all the way or drill and bore? What do you use to push the reamer with? I use a floating pusher or sometimes a dead center. My tail stock is with in .001 up and down and left to right. I have had a few barrels now win and or place very high in some br matches so I am comfortable with my methods but I am always looking to learn. Thanks lee
Is it really this easy?
I finally made a barrel extension so I can chuck a barrel into our SB13 spindle:
I chucked up a test barrel (20 inch Rem 700 TAC takeoff) and a decent Brown & Sharpe DTI setup with a 2.75 inch stylus and planned on spending a few hours learning to dial it all in and after about 5 minutes, I had it pretty close:
https://www.youtube.com/watch?v=_zvqW1-MK1Y
It all seemed too easy. Did I just get lucky? I chucked up another 26 inch test barrel and it went just as smooth.
I finally made a barrel extension so I can chuck a barrel into our SB13 spindle:
I chucked up a test barrel (20 inch Rem 700 TAC takeoff) and a decent Brown & Sharpe DTI setup with a 2.75 inch stylus and planned on spending a few hours learning to dial it all in and after about 5 minutes, I had it pretty close:
https://www.youtube.com/watch?v=_zvqW1-MK1Y
It all seemed too easy. Did I just get lucky? I chucked up another 26 inch test barrel and it went just as smooth.
Gene, you got it, it's pretty much that easy.
Not sure I like that much barrel hanging out of the chuck though, but that is just my preference. On any of my lathes, that thing would chatter like a sumbitch parting off the stub. I am using a live center now on the small lathe to help that some. CHatter is why I got away from using a spider on the breech end, a chuck is a lot stiffer workholder. I've been playing with a collet setup a bit, to try and get stiffer yet, but the headstock gets pretty long doing it that way. I already removed the extensions on the set tru chuck to shorten that some.
That sure is a RED lathe though!!!
Not sure I like that much barrel hanging out of the chuck though, but that is just my preference. On any of my lathes, that thing would chatter like a sumbitch parting off the stub. I am using a live center now on the small lathe to help that some. CHatter is why I got away from using a spider on the breech end, a chuck is a lot stiffer workholder. I've been playing with a collet setup a bit, to try and get stiffer yet, but the headstock gets pretty long doing it that way. I already removed the extensions on the set tru chuck to shorten that some.
That sure is a RED lathe though!!!
Another problem with that much barrel sticking out is it makes it harder to indicate. You usually want the tip of the indicator when all the way in, to be on the pivot point of the barrel. This way you indicate the chuck in first, and when you adjust the outboard spider you arent changing the inboard adjustment (at least very minimally).
But otherwise you got it, I think its easier than rods as long as you do the above.
But otherwise you got it, I think its easier than rods as long as you do the above.
This has been an interesting and informative thread. It gives me some new options. As you can see I like options
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On the second barrel I dialed-in, I marked it at 2 inches and marked the indicator stylus as well.
After reading comments, I decided I'd give it a whirl. 2 inches and a wire collar was still not rigid enough; I got a little chatter but it pretty much got masked by the threads.
I cut an 11 deg crown by setting the cross slide to 11, but it didn't come out very well. Lousy 4140 (or whatever Remington uses).
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