indicating in barrel
- Thread starter DS
- Start date
Results are ok, but bores seem to be tapered at the opening as often as not. This causes the rod with the same bushing size to jump around a bit and "bounce" the hand on the indicator. A burr on the edge of the groove can cause the same condition. A pin which is more of a press or sliding fit into the bore may iron down the burr, if it's there, and give a smoother reading on the indicator dial. Long story short, I get smoother indicator readings by using a pin vs. using the reamer bushing on a rod. I really don't seem to see any difference on target regardless of which method I use.
One of the results of Gordy's technique that I like is the indexing of the muzzle.
Have chambered up sereral bbls for Long Range only to find out that I needed 3 MOA of rt or lt windage to center/zero the rifle.
The indexing can eliminate this and help give you all the windage that your rear sight has built into it.
That said, I have never had to use all the windage that my rear sight had
Bob
Have chambered up sereral bbls for Long Range only to find out that I needed 3 MOA of rt or lt windage to center/zero the rifle.
The indexing can eliminate this and help give you all the windage that your rear sight has built into it.
That said, I have never had to use all the windage that my rear sight had
Bob
butchlambert
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Bob,
I did that one time and had to adjust alot for vertical. Ain't no free rides. A barrel will have taper in the breech from lapping. You really need to cut 1"-2" off before chambering.
Butch
I did that one time and had to adjust alot for vertical. Ain't no free rides. A barrel will have taper in the breech from lapping. You really need to cut 1"-2" off before chambering.
Butch
DS said:
I'm trying something new (new to me at least) from JGS and I think I like the idea. They make a pin in either a 4" or 10" length that accepts a reamer bushing on one end and has a taper about 2" further down the pin. The bushing can be changed to fit the bore and the taper on the shank will center in the open end of the bore. You can then use the pin to indicate your bore. Use the short pin for single indicator or the long pin for double indicators. Saves having to buy several different sizes of pins for each caliber and the long pins are hard to find anyway. I'll soon know how they work.
butchlambert
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clowdis,
After you are through indicating with your rod, pull it and reinstall it. See if it doesn't indicate differently.
Butch
After you are through indicating with your rod, pull it and reinstall it. See if it doesn't indicate differently.
Butch
butchlambert said:
I'll give that a try. What method do you advocate? Frankly I would expect a slight difference from almost any method after a "teardown" and resetup though whether it be a single pin, the Gritters method, or even indicating the bore. That's why we have a pilot on the end of the chamber reamer, to take care of slight misalignment issues. No matter what we do we aren't going to get the bore/spindle/tailstock all in perfect alignment before we cut a chamber. I believe that the most important thing is to get the pilot bushing fitting correctly so the throat aligns perfectly with the bore and then you're going to cut a good chamber if other things are reasonably aligned.
butchlambert
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Clowdis, I was speaking of doing your indicating, then pull your rod and put it back in without moving anything. I think you will find that it indicates differently. We all do things a little different. I do not want a bushing to influence my chambering.
Butch
Butch
butchlambert
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Briefly,
I indicate both ends with Deltronic pins. I predrill my chamber, that allows me room to reach into the throat with a small body Mitutoyo 513 tenth indicator. Now I taperbore the chamber with a short stiff solid carbide boring bar. I put a loose fitting bushing on the reamer and cut the last .035-.045. I want the reamer to follow the hole that I bored true to the throat and lathe bearings. I do not want the reamer to be influenced by the bushing.
Butch
I indicate both ends with Deltronic pins. I predrill my chamber, that allows me room to reach into the throat with a small body Mitutoyo 513 tenth indicator. Now I taperbore the chamber with a short stiff solid carbide boring bar. I put a loose fitting bushing on the reamer and cut the last .035-.045. I want the reamer to follow the hole that I bored true to the throat and lathe bearings. I do not want the reamer to be influenced by the bushing.
Butch
Butch,
Now here we could begin the never ending discussion about whether or not the bores are straight or rainbows Your method assumes they are straight and mine assumes they are not. The answer is somewhere in between because nothing is perfectly straight and these bores are not as crooked as some people would have you believe. I have drilled a few bores with a gundrill and I can tell you that these things are GOOD! I suspect that most of the really "crooked bore" stories are the result of an improper measurement or other observation. On the other hand, I doubt that any bore is absolutely perfectly straight. Every 'smith has his method and as long as thought is given to a correct setup method and care is taken in the machining a good chamber should be the result. I prefer the fitted bushing method because I believe that the throat/neck area of the chamber is the most critical part of the chamber and that this is the best way to insure that this part is concentric with the bore of the barrel.
Now here we could begin the never ending discussion about whether or not the bores are straight or rainbows
Your method assumes they are straight and mine assumes they are not. The answer is somewhere in between because nothing is perfectly straight and these bores are not as crooked as some people would have you believe. I have drilled a few bores with a gundrill and I can tell you that these things are GOOD! I suspect that most of the really "crooked bore" stories are the result of an improper measurement or other observation. On the other hand, I doubt that any bore is absolutely perfectly straight. Every 'smith has his method and as long as thought is given to a correct setup method and care is taken in the machining a good chamber should be the result. I prefer the fitted bushing method because I believe that the throat/neck area of the chamber is the most critical part of the chamber and that this is the best way to insure that this part is concentric with the bore of the barrel.butchlambert
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I think you are right that most bores are pretty straight. Now think about your method. If there happens to be a very slight curve to the bore, what is happening when the barrel is spinning? Even indicating with the Gritters method the .0002 slop between the indicating rod and bushing and you have another .0002 clearance between the bushing and the bore. A .237 bushing will not fit in a .237 hole and a bushing without .0002 clearance on the rod will lock up. If you use my method, it will be straight from the base of the case to the throat. You are machining out any runout at the base when you taper bore.
If you haven't worked in the machine shop it may be a little hard to understand.
Butch
If you haven't worked in the machine shop it may be a little hard to understand.
Butch
The method of chambering has gone round and round for years now. To each his own, not saying one method is better than another. The result is what matters.
I have a customer whom I chambered 5 barrels now, all in 308 Winchester.
One, I chambered as Gordy does and it shot well setting a couple of national records
The others I indexed both ends to less than .ooo2
These barrels all shot well and set a couple of national records.
The barrel done gordy's way the barrel was indexed up at the muzzle.
As expected this barrel shoots 6-8" higher at 1000 yards.
All 4 of the barrels dialed in on both ends shoot 6-8" lower but within 2" of each other (verticle) at 1000 yards. All shots were with 185 Bergers.
Nat Lambeth
I have a customer whom I chambered 5 barrels now, all in 308 Winchester.
One, I chambered as Gordy does and it shot well setting a couple of national records
The others I indexed both ends to less than .ooo2
These barrels all shot well and set a couple of national records.
The barrel done gordy's way the barrel was indexed up at the muzzle.
As expected this barrel shoots 6-8" higher at 1000 yards.
All 4 of the barrels dialed in on both ends shoot 6-8" lower but within 2" of each other (verticle) at 1000 yards. All shots were with 185 Bergers.
Nat Lambeth
Nat,
I suppose those would be the ones you've done for Jeff. I do the ones for Kent's Palma rifles including the one he set the new National record with last month at LeJeune. While you, Butch, and I all have slightly different methods of chambering, all work well, and that's what I'm getting at. I'm anxious to try the JGS pins when they get here to see how I like them. I don't think they will be much different than setting up with deltronic pins, but I may be wrong. I may stay with the Gritters method and just work further up the bore. I think it's a credit to the barrel makers that we can sit here and argue about 6 or 8 different makers being "the best" and everyone be right
I suppose those would be the ones you've done for Jeff. I do the ones for Kent's Palma rifles including the one he set the new National record with last month at LeJeune. While you, Butch, and I all have slightly different methods of chambering, all work well, and that's what I'm getting at. I'm anxious to try the JGS pins when they get here to see how I like them. I don't think they will be much different than setting up with deltronic pins, but I may be wrong. I may stay with the Gritters method and just work further up the bore. I think it's a credit to the barrel makers that we can sit here and argue about 6 or 8 different makers being "the best" and everyone be right
This is always such an interesting topic to so many guys and people learn a lot from posts like this, which get people to thinking.
I traveled and taught a chambering school to some gunsmiths at a tactical rifle manufacturer awhile back and they had been using the tapered range rods with a bushing on the end. I told them I was never able to get those to repeat accurately since the taper first had to seat into the end of the bore exactly the same every time, which would be almost impossible to do, and second it depended on the end of the bore (or throat if dialing in a previously chambered barrel) being perfectly true, which also didn't always happen either.
So we tested it - we very carefully dialed a bore in with their rod so it was running as dead true as we could get it - the indicators read dead zero! Then we took the range rod out and re-inserted it repeatedly like Butch just mentioned and the indicators now weren't close to zero at all - we never could get it to repeat accurately at all. They were getting it fairly close using that method, but definitely not nearly as perfect as they thought, which the testing showed. Made a believer out of them very quickly not to trust those rods.
Don't forget I use more than just a range rod to dial in barrels - I use 2 things: the long single-bushing range rod to get it really close and a long reach indicator to fine tune it even closer after that. I use the range rod to start out with since it will go so much farther up a barrel ahead of the throat than any indicator will reach - this gets this end of the bore dialed in very close and running very straight. But there is sometimes a little runout still present due to the clearance between the bushing on the rod and in the bore - rarely over .0002-.0003" though, which would still be extremely good.
But I've pre-drilled the chamber so after dialing the bore ahead of the chamber as true as I can with the range rod, I can reach in to the throat area and up to 1 1/2" ahead of the throat with the long-reach indicator to fine tune the dial-in to get rid of any runout that may still be there - you can quite easily get close to .0001" anywhere from the throat forward as far as the indicator will reach. Now with the bore from the throat forward running this true it's time to bore the chamber hole true (you can straight bore it or taper bore it - both will work extremely well). So now you can put a .0001" indicator all the way through the chamber, and as far ahead of the chamber into the bore as it will go, and it will all be running perfectly straight and true.
There definitely is more than one good way to dial in barrels, as everyone knows, but after trying and using different methods over the years, this has become my favorite method so far since I can test it with indicators and and repeat it every time no matter how much curvature is in a bore. I've not been able to find any method that gets the chamber aligned to the bore any better and straighter than this in my opinion, and be able to accurately test and measure this with sensitive indicators both in and quite a ways ahead of the chamber every time no matter what.
Gordy Gritters
www.ExtremeAccuracyInstitute.com
I traveled and taught a chambering school to some gunsmiths at a tactical rifle manufacturer awhile back and they had been using the tapered range rods with a bushing on the end. I told them I was never able to get those to repeat accurately since the taper first had to seat into the end of the bore exactly the same every time, which would be almost impossible to do, and second it depended on the end of the bore (or throat if dialing in a previously chambered barrel) being perfectly true, which also didn't always happen either.
So we tested it - we very carefully dialed a bore in with their rod so it was running as dead true as we could get it - the indicators read dead zero! Then we took the range rod out and re-inserted it repeatedly like Butch just mentioned and the indicators now weren't close to zero at all - we never could get it to repeat accurately at all. They were getting it fairly close using that method, but definitely not nearly as perfect as they thought, which the testing showed. Made a believer out of them very quickly not to trust those rods.
Don't forget I use more than just a range rod to dial in barrels - I use 2 things: the long single-bushing range rod to get it really close and a long reach indicator to fine tune it even closer after that. I use the range rod to start out with since it will go so much farther up a barrel ahead of the throat than any indicator will reach - this gets this end of the bore dialed in very close and running very straight. But there is sometimes a little runout still present due to the clearance between the bushing on the rod and in the bore - rarely over .0002-.0003" though, which would still be extremely good.
But I've pre-drilled the chamber so after dialing the bore ahead of the chamber as true as I can with the range rod, I can reach in to the throat area and up to 1 1/2" ahead of the throat with the long-reach indicator to fine tune the dial-in to get rid of any runout that may still be there - you can quite easily get close to .0001" anywhere from the throat forward as far as the indicator will reach. Now with the bore from the throat forward running this true it's time to bore the chamber hole true (you can straight bore it or taper bore it - both will work extremely well). So now you can put a .0001" indicator all the way through the chamber, and as far ahead of the chamber into the bore as it will go, and it will all be running perfectly straight and true.
There definitely is more than one good way to dial in barrels, as everyone knows, but after trying and using different methods over the years, this has become my favorite method so far since I can test it with indicators and and repeat it every time no matter how much curvature is in a bore. I've not been able to find any method that gets the chamber aligned to the bore any better and straighter than this in my opinion, and be able to accurately test and measure this with sensitive indicators both in and quite a ways ahead of the chamber every time no matter what.
Gordy Gritters
www.ExtremeAccuracyInstitute.com
Gordy,
Thanks for weighing in on this. One thing I've found that agrivates me when dialing in a bore is a land that doesn't indicate the same as the other 3 or 5 or whatever because of a burr or something that will cause it to read at tenth or two off. I also agree that anything that goes into the bore must have clearance in order to go into the bore whether it be a bushing or a deltronic pin. If it didn't it wouldn't slid in. Hence my continuing search and a try with the tapered pins. A gift certificate won at the Midwest Palma matches didn't hurt any either, so that's the reason I was shopping at JGS and came upon the pins. But with the taper on the end of the pins there will be no clearance between the pin and the bore at the bore exit, so an indicator reading at the exit might be pretty good IF the bore is good there. Here again I'm just guessing, but the readings would get more unreliable the further out you go on the pin due to the clearance on the bushing. I don't know how far the bushing is from the taper and this too will have a great effect on the quality of the indicator readings. Like I told Butch, I'll try them when they get in and just see what kind of readings I get and go from there. How good is good enough? I guess that's the question we're all trying to answer.
Blair
Thanks for weighing in on this. One thing I've found that agrivates me when dialing in a bore is a land that doesn't indicate the same as the other 3 or 5 or whatever because of a burr or something that will cause it to read at tenth or two off. I also agree that anything that goes into the bore must have clearance in order to go into the bore whether it be a bushing or a deltronic pin. If it didn't it wouldn't slid in. Hence my continuing search and a try with the tapered pins. A gift certificate won at the Midwest Palma matches didn't hurt any either, so that's the reason I was shopping at JGS and came upon the pins. But with the taper on the end of the pins there will be no clearance between the pin and the bore at the bore exit, so an indicator reading at the exit might be pretty good IF the bore is good there. Here again I'm just guessing, but the readings would get more unreliable the further out you go on the pin due to the clearance on the bushing. I don't know how far the bushing is from the taper and this too will have a great effect on the quality of the indicator readings. Like I told Butch, I'll try them when they get in and just see what kind of readings I get and go from there. How good is good enough? I guess that's the question we're all trying to answer.
Blair
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