Barrel - Lathe set up
Help me understand? I just watched a video demo clip of a apparently well regarded gunsmith setting up a barrel in the Grizzly lathe infomercial with a bushing range rod held in a jacobs type chuck in the tail stock and indicating on the rod first with it inserted at the breach end and then in about two inches further using the tail stock. He held the range rod in the tail stock jacobs chuck. I too set barrels up thru the headstock, 4 jaw and spider with a bushing to minimize chuck contact, but I use the tapered bushed range rods in both ends of the barrel. I insert the rod until the taper prevents further insertion, the indicate off the rod OD close to the barrel I never use the tailstock. I adjust and re-adjust until I get best results for TIR, with primary focus on the breach end. I also move the indicator out an inch or two on the range rod and check TIR there to see if the barrel bore in the portion which will be the future chamber is running parallel with the head stock spindle, assuming that not all barrel borings are straight from end to end. For this reason, my future muzzle end TIR is less important than the breach end at both indicator location. Help me understand how a person could hope to get accurate set up with a range rod fixed in the tailstock in something as inaccurate as a jacobs chuck and moving it in and out using the tailstock ram?? To me, the measurements would be affected by the tailstock alignment vertically, and the accuracy of the tailstock ram, and the chuck and the fact that most range rods are tapered and will not chuck up exactly parallel to the headstock spindle. So, please help me understand what I'm missing. I'd especially lick to hear from the guy who did the video, but I don't know how to reach him as I only say the U-tube clip. Thanks
Do a search for Gordy Gritters (the gunsmith in the video) and all of your questions should be answered as this was discussed in great detail awhile ago.
Originally Posted by Kodzoff
Watch it again.
Your way off base.
Gordy is a good friend of mine but I don't agree with the way he sets his barrels up. It works to his satifaction and that's all that matters. Here is what he is doing.
He is aligning two points in the breech end of the barrel. He's doing this by holding the rod in the tailstock and moving it to two different locations in the barrel. Accuracy of the chuck or alignment of the tailstock doesn't come into play here. He adjusts the barrel on the outboard side and inboard side until those two radial slices of the barrel are in alignment. Zero runout on the rod in each location as he rotates the barrel. He thinks this aligns the reamer better in the barrel. When he threads the barrel he indexes it so it is pointing to the top of the action.
I've never tried Gordy's method but using a long stem indicator in the throat/neck area I've never felt I needed to try another method. I just did a 300 RUM Imp for a customer and had less than a .0001" TIR in the neck and chamber mouth. The needle didn't move on my .0005" indicator in either location and that's with the muzzle running under .0002". I can't get it any better than that.
Thanks for the replies. I now have read the other threads on Mr. Gritters video, and if nothing else, he'll likely sell me a copy just so I can review it completely at my leisure. Dave, I think I understand what he is trying to do, but I cannot see how the position of the tail stock hold on the rod is irrelevant. Two points make a straight line. Those points are the tailstock end of the rod and the bushing end of the rod. If you adjust the barrel so the rod stops moving, the barrel bore at the point of contact with the rod is in alignment with the tail stock end of the rod. If you move the rod with the tail stock into the barrel further and again align the barrel, that point will also be in line with the new position of the end of the range rod. If you continue the process until all three points are in alignment, then all three points are on the same line. However, unless the tailstock spindle is in dead alignment with the lathe spindle, all that you have done is put the first several inches of the rifle barrel blank bore in dead alignment with the centerline of the tailstock spindle Remember, it is the tailstock spindle that is moving in and out for the inner and outer measurements, and it's holding the other end of the range rod. Am I still not getting it???
Originally Posted by Kodzoff
The range rod is designed to flex so tailstock alignment is irrelavent.
As you rotate the barrel, the range rod deflects, giving you a place to put an indicator.
One of the weakness of the range rod is that there is clearance between the rod and bushing. This can be partially overcome by bending the rod very slightly, so it holds some side pressure on the rod/bushing at the tip.
Consider this...it is actually desirable that the tailstock is out of alignment slightly. to minimize a dead band in the bushing (clearance) as you rotate the barrel.
I have tried Gordy's method of indication, honestly giving it a try, and I find it unneccesary. What you might gain in more accurate angular alignment, does not outweigh what you lose in other places, such as muzzle alignment, and repeatability for setback.
At this point in my learning curve, I still think direct indication of the throat and muzzle is a superior procedure.
Thank you Ben. After some more visualization, and your help too, I now understand. The tailstock merely acts as a pivot point, which is why Mr. Gritters chucks it very shallow and says the longer the rod the better to a point. I understand your considerations as well regarding the runout on the bushing. Again, thanks to all.
Setting up barrels..
Not getting into what is better or who is right. There are several schools of thought on this subject. I have talked at length with Gordy and Greg Tannel who uses a simular approach. We all agree with one thing no matter the method, that deep hole drilled barrels have a wondering bore. Therefore the bullet is going to have a wondering path between the breech end and the muzzle. Many smiths feel they get a better shooting rifle ifs they align the bullet and case both coaxially and concentrically at the breach end. This can only be accomplished by moving the muzzle off center. There are many smiths that feel that both the breach end and the muzzle end should be centered independently. There theory is a bullet started off straight and ending up straight is the best theory. Jackie often talks of stacked tollerences. Barrels no matter the method a barrel should be shimmed in the headstock so they can turn without flexing. Both methodologies work and I am not one to say one is better than the other.
Shooters today are expecting more and more out of their equipment. The BR crowd at 100 and 200 have to have a rifle capable of shooting groups in the single digits on good days. The Long range BR shooters are seeing 600 yard groups under an inch on good days. The 1000 yard BR shooters are shooting groups right at 3" on good days. Yesterday I had an F-Class Open customer shoot a 200 with 14 Xs at 600 with a Savage Target Action and 31" Broughton 1:8 5C in 6mmBRX. He had a 5 shots in a row, in a 1.75" spotter disk before nocking the center out.
Guns and the ammunition have gotten so much better in the last 5 years.
Gunsmiths like Dave Tooley, Gordy Gritters, Greg Tannel, all have record winning guns and for good reason. They are learning from each other everyday. I wish everyone of these guys would make DVDs on their barreling processes.
Whatever method you choose, somebody will tell you that you are wrong.
I once thought I was wrong, but I was mistaken.
Originally Posted by Butch Lambert
And many others here think like me.....
Last edited by Bnhpr; 10-19-2008 at 07:58 PM.
Your right, we all learn from each other. I was lucky when I first started shooting BR 30 years ago and got to hang out, no internet then, with some pretty good smiths of the day. Then as now they were all very generous in sharing information. I listened, I asked questions, I learned and developed my own techniques. Which BTW have changed over the years. Better/different equipment, better inspection equipment and a better understanding of the process and the compromises involved.
Compromise- that's a word that hasn't been used. Every setup and every chambering process is a compromise of some kind. There are no absolutes.
Learning the Process..
Ken Ryan was a hell of a gunsmith. As is Charlie Joins, James Messer, Leonard Baity, and the North Carolina gunsmith list could go on an on. I did my first barrel over 40 years ago and my technique is nothing like what it was back then. But listening to you, Mike Bryant, Greg Tannel, Jackie Schmit, Mickey Coleman, Butch and others has kept my mind open. I also started reading and collecting books on rifle building. Today I have maybe 100 books about rifle building and chambering. I have been lucky enough to meet and talk with some of the masters. The internet has brought many of the current masters to a common ground. There are a cadre of good smiths who don't shoot anymore. With the opening of Montgomery Tech and Piedmont Tech gunsmithing programs there are new smiths on every block here in North Carolina.
I'm with you 110% Nat....
Originally Posted by Rustystud
...The information I've learned here in, is world class.
There are no words to give the gunsmiths enough credit.
I really appreciate the efforts of those mentioned above, and many more that have helped me in the shop and on the bench.
Another common method that does not require indexing
For the chambering;
First determine where you want the muzzle based on barrel taper and the weight you need. eg LV, HV Max HV, etc. I use Dan Lilja's program to calculate weight if I am not duplicating a previous barrel.
Cut the barrel off at the muzzle end to about 1/8" of finished length. In setting this up indicate the barrel OD sticking out of the tail end of the headstock. Using something like a South Bend Heavy 10 so you can work a barrel through the headstock down to about 18" long. On the muzzle end, indicate the OD at the cut point.
Some barrels will have concentricity errors from OD to ID as much as 1/16". Not a problem. You not working in the ID just yet, just cutting the muzzle end to near finish length.
Then turn the barrel around and indicate the OD on the chamber end and a gage pin in the muzzle end. Then cut to approx length with a parting tool just as you did for the muzzle.
At this point with the barrel spinning about 200 rpm look down the bore to see how much curve is in it. Over the years I have had to send 2 barrels back that I thought runout was excessive. Both looked like a girls 2-girl jump rope. I don't reorder from them again.
Now, with a snug fitting gage pin in the muzzle end position a dial indicator on that gage pin. I use an Interapid 0.0001" dial indicator with a probe long enough to reach the chamber neck area. Dial both ends in. The muzzle end dial in to the nearest 0.001" using the spider. Dial the chamber neck in to 0.0000" or as near that as you can get.
Rough the tenon to about 0.01" over finish size and to length. Pre drill the chamber body to about 1/64 under chamber shoulder/body finish size and almost to the finish shoulder (leave about 1/32" or so for the reamer shoulder to finish.
Next reindicate the muzzle end and the chamber neck. Didn't move so go on. On the chamber neck indicate the lands. That's where the neck pilot rides.
Bore the drilled hole to about 0.005" under the shoulder finish diameter then step bore a couple more 0.005" steps in the larger part of the chamber body taper. Don't try to taper bore the chamber body. Too many places to screw up oncluding cutting a surface the reamer will grab on. In most chambers the reamer pilot is already in the barrel bore anyway.
Rough the barrel cone if it is a cone bolt or the counterbore if it is something like a Rem 700.
Finish the tenon OD and shoulder. Make sure the shoulder is very square and no corner radius with the tenon OD.
Finish the chamber gaging off the tenon shoulder. Use a floating pusher that is shown in several posts on this forum.
Finish the barrel cone and thread.
Turn barrel around and indicate the muzzle ID with an Interapid indicator. On the muzzle end indicate the grooves because I sometimes put a 0.005" x 45 bevel. Indicat the tenon OD in this same setup.
When finished a barrel it will be on paper to within +/- 2" at 100 yards from the barrel just taken off if that barrel was done by this method.
Thank you Jerry for your very detailed post. On the barrel I just completed I experimented around a bit. I tried Gritters range rod approach, but I sure didn't like the muzzle end runout. May be psychological, but it bothered me. I made my initial set up on pins as I have done before and then tried your approach of roughing the chamber with stepped boring and then finalizing the set up directly indicating at the throat area. That gave me the clear access to get everything dialed in before finishing anything. That way the tenon, thread and chamber are all done on that final direct throat indicated set -up. The result were excellent, nice straight tight round chamber concentric at the throat and breach mouth. I also again used the Lambeth - Kiff micrometer reamer stop. This was the second time I tried it with a cone breach, but this time I did not bother second checking with my normal infeed indicator set up. It worked perfectly, resulting in headspace less than .002 (go guage with one layer of cello tape would not close) I really like it and unless I experience problems, I may never go back to the old way. BTW, the first cone breach barrel I completed with the reamer stop shot a 100 yd LV bench match group .123 on the way to a .2312 agg and 7th place. The tool certainly does not adversely affect accuracy.