Gritter's chambering video

Exit Bore

Jerry,

Simply, Gordy does account for the Exit Bore position.

How? Someone more knowledgeable than me will need to answer that. I'm going to watch the Video again...and again..and again...lol

-John

:)
 
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Jerry
I only chamber my own barrels so I always have the action on hand.
When you chamber a barrel without the action how do you determine where to stamp/engrave the cartridge information on the barrel? If you can get that in the exact clocked position you want it on the finished rifle I would think you could use the same technique to index the muzzle up. As I said I don't know just giving you ideas.
The reason for looking at the mitutoyo indicator is the small round body that can be inserted into the rough drilled chamber so as to get a direct reading into the bore. That is the only indicator that I have seen that will do that. Are there better quality ones that will accomplish that too?
James
 
Chambering

I finally got that download to work on my computer, and now see what Gordy is doing.
He is simply using the range rod as a substitute for a stylus on the indicator. The rod flexes. (the pivot is in the tailstock end), as the bore runnout is transfered through the bushing to the rod. The indicator stylus picks up the reading.
Several Gunsmiths I know use the same method of chambering. In other words, they are only interested in the first couple of inches of barrel that the reamer will actually be influenced by. If you get these first couple of inches dead true, you don't worry about everything else. The muzzle will, however, always exibit quite a bit of runnout, depending on how straight the bore is with its self.
I have never liked this method. The main reason is it is very difficult to set a barrel back up, which I do on a regular basis for set-backs. Second, some barrels have quite a bit of runnout,(as Jerry has noted, this can be in the form of several different curves), and I just do not like that much muzzle runnout.
I still favor the two point method, where you establish two dead true points, (that being the muzzle and the throat area), bore everything else on the chamber end in alignment with that, and then let the reamer follow the bored hole, assisted by the pilot. .
Keep in mind, if something is not straight, it is impossible to indicte more than two points dead true. (Unless you bend the piece). What you have to do is decide what two points you want, and work from there.
The basic difference in what Gordy does and what I do is what two points we decide to indicate dead true.
As I have said before, what really counts are the results. I would personally not use the methods described in this video, but if they work for Gordy, that is what counts..........jackie
 
I have a question for you guys that indicate the muzzle. Do you try to find out which way the bore is actually pointing when the muzzle is running true? Do you run some sort of indicator several inches into the bore at the muzzle to see which way it is pointing ?

Thanks
 
Jerry
I just re-read through this thread and saw that you probably haven’t watched the video clip on 6BR.com so a lot of what I posted probably doesn’t make sense.
Your description of the bore being a compound curve is probably a better description than what I have been calling a helix. I guess I couldn’t come up with a better description and was thinking what it would be if it continued on past the end of the barrel. From now on I’ll call it a compound curve, maybe people will understand what I’m talking about then.:D
I’ll try to clarify some stuff.
The barrel is set up through the headstock with a spider on the outboard end.
The first 2to3” are then indicated in on the chamber end using the rod I described in an earlier post that is in the drill chuck in the tailstock. The rod is moved back and forth to adjust the chuck and spider until there is no runout in the 1st 2 to 3” of the bore.
After the barrel is indicated in, then put an indicator on the muzzle end and turn the lathe and find where the highest point of runout is and mark that as the point that will be up when installed on the action.
This method doesn’t address the radial curve of the bore at the muzzle, but then neither does centering both the muzzle and chamber end like most gunsmiths do.
James
 
Chisolm said:
Jerry
I only chamber my own barrels so I always have the action on hand.
When you chamber a barrel without the action how do you determine where to stamp/engrave the cartridge information on the barrel? If you can get that in the exact clocked position you want it on the finished rifle I would think you could use the same technique to index the muzzle up. As I said I don't know just giving you ideas.
The reason for looking at the mitutoyo indicator is the small round body that can be inserted into the rough drilled chamber so as to get a direct reading into the bore. That is the only indicator that I have seen that will do that. Are there better quality ones that will accomplish that too?
James
Click to expand...
James, many of the top custom actions have the same index point. I can change a barrel from one Panda to another and the print comes out at the same location...that is only if the Action or bolt face haven't been dickied with. But then again, many of other top custom actions do not have the threads starting in the same location.

Indicators? Read this web site well if you are interested in dial indicator precision and design.
http://longislandindicator.com/p116.html From this page go back to the first page and look at the others. They are listed alphabetically.

And yes I saw the video on 6mmbr.com and youtube. That is when I really started questioning that method of barrel alignment.
 
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jackie,

You stated that "and I just do not like that much muzzle runnout." . Gordy indicated the muzzle end of the barrel the same way he did the chamber end so when he crowned the barrel it was square to the bore, isn't that what you want? The way I take it in the video, if you do the indicator on both ends , the bore could be at a slant to the crown. And I take it that it doesn't make any difference what the bore does between the throat and the muzzle .
Hope this makes since, I'm just trying to under stand the video and the posts here.
Thanks ,Art

PS: I just received the video Saturday.
 
Jerry,


Please elaborate on this statement .......... "If the bullets exit point from the bore is not in perfect alignment in the horizontial (left-right) plane with the stock/action the gun will not track correctly."


Explain how you measure and correct for this?


al
 
Video please..

Can someone make a 90min video of the two-point method.

Until then...;)
 
alinwa said:
Jerry,


Please elaborate on this statement .......... "If the bullets exit point from the bore is not in perfect alignment in the horizontal (left-right) plane with the stock/action the gun will not track correctly."


Explain how you measure and correct for this?


al
Click to expand...
Al, if the barrel is pointing to the side, left or right, the gun will jump to the side, just like a bad bedding job where the action is crooked in the stock.

Action, equal and opposite reaction, comprande'?

How do you correct for this? chamber and fit the barrel so that the exit point is in alignment with the action/stock assembly.

There is apparently a method used called "clocking" the muzzle. A lot of extra work for a problem that was needless. One poster on this form some weeks ago points the muzzle up do gravity will pull it down??? Thass what he said anyhoo.
 
Notes on the Grizzly chambering DVD

I certainly do not feel like anyone has been bashing me - it's just nice to see some discussion and other opinions on this topic. There definitely are other ways to set up and chamber barrels that work very well, but the way I'm currently doing it has produced consistently better results for me than ways I've done in the past.

I am a full-time gunsmith and have been doing this for about 21 years now. I do from 50 to 75 barrels a year and I've always continually experimented to try to find better ways of doing things. I did it between centers for awhile, and then for a long time I did it by indicating at the throat and the muzzle like a lot of guys do now and got along just fine, but when I changed my methods and started to set the bore up so the chamber perfectly aligns to the first few inches of bore AHEAD OF THE CHAMBER like I do now, my percentage of "so-so" barrels noticeably went down and the number of "hummer" barrels went up.

I first noticed this when I saw in my bore scope that the throat wasn't always as perfectly true as it should be. Then when I measured with an indicator, the chamber and the throat would be perfectly true, but even as close as 1/2" ahead of the throat I was surprised just how much runout there would be on some of these barrels (the more curvature in the barrel, the worse this is) - this really bothered me since my customers were paying good money and I felt I wasn't giving them their money's worth. Doing it the way I do now, I can measure the back of the chamber, the front of the chamber, the throat and 2" or more up the bore ahead of the throat and everything is still running straight and true - every single time - which is exactly how I want it.

You guys are right about the range rod. It doesn't turn so it doesn't matter if it's true or not. If the bore is running out, it will flex the rod along with it and this is easy to measure and use to get the bore running true. After I get it running true with the range rod, I always double-check the bore (and fine tune it if needed) with the dial indicator since it will give a more accurate reading than the range rod can (range rod bushing has clearance in the bore, it runs on top of the lands which aren't always true, and the bushing itself isn't always perfectly true).

I try to control everything as much as I possibly can, so I then started to index the "high side" of the muzzle end of the barrel so it pointed up. When setting a barrel up like this, even though the curvature in the bore isn't always "straight up" but sometimes will also curve a little right or left of center also (compound curve), the bore will still be generally be pointing up or close to it. This makes it better for long range shooting. I used to worry about the muzzle runout using this method, but after seeing the results for me, I sure don't worry about it any more. But the bigger benefit in my mind is no matter what the bore is doing at the muzzle end, I don't want the WEIGHT of the barrel at the muzzle hanging to the side at 3 o'clock or 9 o'clock - I feel this could be cause for more problems from harmonics and barrel whip.

There are so many details that are not on the DVD, but we hopefully cover the basics well enough for just about anyone who watches the DVD to do it that way if they want to and end up with extremely good results- that was one of the main purposes of this DVD! Hope this addresses some of what you guys are wondering about.

Gordy Gritters
 
I have experienced the same thing as Mr. Gritters in my short experience of barrel chambering. I use an indicator to reference off the grooves and not the lands, but that limits how far I can indicate in past the throat. I have seen the same runout in front of the throat that Mr. Gritters describes when the muzzle end is running true. I was always a little uncomfortable with the runout at the muzzle end when I had my indicator readings true for the throat end of the barel. I have to be extremely "fussy" about getting very small runout readings ahead of the throat, since I can't reach in there very far (only about 2.5").
 
Jerry,

I have had a lot of bag guns and my experience has been that the misalignment of the actons in the stock has been many magnitudes greater than any misalignment that could come from muzzle runout. Untill a greater number of gunsmiths go to some type of fixture to deal with alignment when bedding, I'm afraid that will be of much more concern with respect to tracking. I can set up my rests and put different rifles with the same stock in the bags and some will point up to 3 feet off of some others.

Just my experience.
Russ
 
Muzzle Run Out

All I have watched of this video is what is posted on 6mmbr.com. From what I see, after Gordy indicates his barrel in forhis chambering and subsequent machining operations on the chamber end,, he pays no attention to what the muzzle is doing as far as runnout is concerned.
Where you can run into a (minor) problem using this method is if you happen to have one of those "squirley" spots exactly where your throat is going to be. What ever this spot runs out will be magnified by the time it gets all the way out to the muzzle end. This can happen quite often in Benchrest, where we often have to cut the chamber end off as much as 3+ inches in order to get the barrel profile at the correct weight.
In reality, this is no big deal. One of my best friends has been setting up barrels this way for years, and his Rifles take a second seat to no ones. He doesn't indicate the barrel in the same manner, but he does indicate that first portion that will influence the reamer.
All I do is establish two points that I want to run dead true, and then I single point bore the part that runs out true with those two points. In the case of a barrel, those two points happen to be the muzzle, and that part of the ID where the throat will form, more or less what the bullet "sees" first as it enters the barrel.

As I stated before, the reason I like my method is it allows me to set barrels up very quickly and efficiently to set them back, which is a big part of my over all Competitive Program. I always have the originol reference points to which to indicate the barrel back in.
This is Machinist Stuff. I am sure Gordy, and other shooters out there who have considerable Machinist Skills, understand this.
As I have said, it makes no difference how you do any of this, as long as the operation produces the tolerances and requirements that the finished piece demands. ..........jackie
 
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Questions for Jackie Schmidt and Jerry Sharrett

Both of you gentlemen advocate having the bore at the throat and chamber run true with the bore at the muzzle.

I understand why you want this but I don't understand how you can depend on achieving this----without a barrel with minimum bore curvature or without the possibility of trimming the barrel in search of throat and muzzle locations that will line up.

I think I fully understand how to locate and ream the chamber and how to crown the muzzle square to the bore as independent operations but the alignment of these two points with each other remains a big question for me.

I once considered that you might be making compromises by having tolerances loose enough to approach alignment but now think this is way off----when you work to .0001" tolerances, you can't be making much compromise.

I'm not a cook book and recipe guy and prefer to understand a job from end to end before starting, if possible.

I'd appreciate any clarification you can provide on how to achieve this.

A. Weldy
 
Lucky Shooter

Shoot well
Peter
 
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It would seem to me that the method Gordy uses to indicate a short section of the bore, perfectly true to the center of the lathe would really pay benefits at the muzzle.

If you simply indicate at one point in the muzzle, the "hole" could still be somewhat out of true with the center of the lathe. When the cown is cut in this set up, it could be at an angle to the bore.

By aligning the bore at two points, in the very least, your muzzle crown will be perfectly perpendicular to the bore.

I'm not sure I would want the involvement of having to set a barrel up to "point up"...But I understand the reasoning, and it's a good one.............

Next barrel I'm going to try this method, but for now I'm certainly incorporating the muzzle set up...........

Thanks Gordy...............Great bit of research there!
 
Comments.

Jackie,

It will be interesting to hear your comments after you have seen the Video in its entirety.

-John
 
Weldy

When I say indicate two points, that is what I mean. The two points that are indicated are no wider than the contact area of the indicator stylus, which, by the way, is round.
No matter what you are truing, you can always arrive at two places that are dead true with each other, and turning true with the axis of the lathe spindle, regardless whether the piece is straight or crooked.
It is when you intruduce the third point is where the problem lies. That is why we establish the "third" point with the single point boring.
From reading some of the comments about this thread, I can see that many of the posters do not understand basic machine shop practice. This is particularlly evident when they cannot seem to understand that if you indicate two points in at the chamber end about 2 or 3 inches apart, there is absolutly no way that the muzzle end can run true, unless it was dead true with those two points in the beginning. And, trust me, unless some miracle happenned during the initial deep hole drilling, it wasn't.
One of the basic tenents I try to instill into young men that I have taght the Machinist Trade to is that to be a good crafsmen, it simply not good enough to know HOW to do things. The true craftsman must learn WHY you do things. Then you can relate basic practices to all endevours.......jackie
 
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Jackie,
I think without a classroom setting, the non machinest will not understand what you are saying. I am not saying this to aggravate anybody, but until you have a complete vision of what's happening, you will not understand what Jackie is saying.
Butch
 
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