Dialing in your bbl

I might add

I chamber much in the same way as Butch and several others, with a few accomadations to suite my lathe. But, one major procedure I do vary on is I establish the chamber first before doing the final machining operations on the tenon.

If you are a Machinist, you will know why I do this.......jackie
 
jackie schmidt said:
I chamber much in the same way as Butch and several others, with a few accomadations to suite my lathe. But, one major procedure I do vary on is I establish the chamber first before doing the final machining operations on the tenon.

If you are a Machinist, you will know why I do this.......jackie
Click to expand...

Jackie,

I'm not a machinist, so I don't know why you do this, but I would.

Justin
 
I establish the chamber first before doing the final machining operations on the tenon.
Click to expand...

I was told that if you did the chamber first, and then did all the machining and threading around it, the chamber diameter would grow ever so slightly.......No?
 
Chambering collection

frwillia;480843].

I have a spam filter that's about as friendly as a mugger in a dark alley, but Joe and a couple of others have followed the instructions and gotten through.

Fitch---------------------------------------------------------------------------------
Hello Fitch;
I have lurked here for a number of years, but never posted. I am very interested in your research and collection of info. If I were to send you a new thumbdrive, would you be willing to load your chambering collection to it and send it back to me..??
I am a pistolsmith and religiously follow the riflesmith forums. The rifle machinists are light years ahead of the pistol smiths who stubbornly cling to antiquated techniques.
I am originally from western Pa. were I grew up on a dairy/poultry farm.

My e-mail address is: Keefer45@msn.com

Thank you

Jerry Keefer
Maidens, Va.
 
RoyB said:
I was told that if you did the chamber first, and then did all the machining and threading around it, the chamber diameter would grow ever so slightly.......No?
Click to expand...
It might, depending on the heat treat condition of that particular barrel but I'll bet you do not have the QC lab conditions and equipment to measure the difference in a normal 1.200"/1.250" blank.
 
JerrySharrett said:
It might, depending on the heat treat condition of that particular barrel but I'll bet you do not have the QC lab conditions and equipment to measure the difference in a normal 1.200"/1.250" blank.
Click to expand...

I agree, it would depend on the heat treat of the barrel, and how the residual stresses act when the tenon and threads are machined.

I wouldn't begin to know how to assess that, or if it would make any measurable difference. A chamber is a rather thick wall tube.

Fitch
 
Roy

As in all correct machine shop practice, you rough out all of the areas within a few thousanths of size, then do all of the criticle indicating and finishing. This negates any possibility of the set-up moving, or any residule stress, (??), rearing it's ugly head.

I make assumptions that when I make post, others understand that machinist follow standard practices that have been proven through the years to insure that a finished piece is indeed what you wanted.

I guess I am going to have to start detailing every procedure......jackie
 
Justin

The majority of hobbyist who do barrel work are really "painting by the numbers". In other words, they are following a set procedure. If anything crops up that could present a problem, or does not follow the script, they lack the skill and knowledge to trouble shoot the operation and adapt as needed.

In general machine shop practice, especially job shop work, you try to perform the most difficult procedures first, because there in lies the possibility of screwing something up. It is simply common sense.

In my opinion,the most difficult aspect of doing barrels is the chamber, especially if you are one who wants every chamber to be exactly the same. By exactly the same, I mean in fit, and in finish. So, what I do, (after roughing out all of the other fits), is true the barrel the way I want it, and then establish the best chamber possible. I then dimension everything else off of the chamber. Even if I misss my headspace when final cutting the shoulder, I can simply run the reamer in a little more and correct the situation.

To me, it seems impracticle to do all of the finish work on the tenon, and then try to ream a chamber to correspond with that. All of this talk about micrometer stops on tail stock quills, trying to ream achamber within the nearest .001. Why?? Good grief, finish the chamber a little long, then face the shoulder, (which you can do in .0001 increments), to arrive at the final length.

But then, I have always said that I am not a Gunsmith. I am a Machinist. To me, doing a barrel is no different than any other job that would come into my shop. You have certain requirements that the finished job must adhere too, and you design a set-up, and use procedures, that insure the finest finished part as possible.

Chambering a barrel, maching a 40 ft long propellor shaft, or align boring the shaft line under a boat with portable boring equipment. It's all machine work........jackie
 
Hmmmmm, I have a Kreiger and a Cobra that sure could use a "mating procedure". Have a brand new Kiff reamer to go with it..........Sorry to have missed the Tomball match, but work had me retrained......freed up now though.

cwood3
 
Jackie

Looks like you might be near the " docks ". I started to dabble in machinery cuz I wanted to build some custom hydraulic reels capable of fishing with light line. I finally ended up with an old lathe and an old Horiz/universal mill.
I really have a great respect for the " boat yard machinist " as I have owned a 40 Striker for the last 30 yrs.
Got the reels perfected and can fish with 100# without breaking them off.
Sorry for rambling off topic.
Next challenge '' gun barrels "

Aloha, Les
 
frwillia said:
I agree, it would depend on the heat treat of the barrel, and how the residual stresses act when the tenon and threads are machined.

I wouldn't begin to know how to assess that, or if it would make any measurable difference. A chamber is a rather thick wall tube.

Fitch
Click to expand...

Fitch..I agree with you
Sounds like black magic again....I think we're reading into this too much.

Although I wonder now after reading Jackies last post, but I originally thought he was referring to basic machinist protocol.....do the hard stuff first.

I used to build valves stems for OSY steam valves, and I learned quickly to rough them out, and machine the double lead ACME threads first, because if you are going to make a mistake, or things are going to move, it will be threading those.

Most of the experienced barrelers here drill and bore the chamber before reaming. This is the only step of barreling that makes me ...I'll say..." a little uneasy" I'm always concerned that I will cut more than the reamer will clean up, way down the chamber, and I'll have to start over. That's never happened to me yet, but I keep pushing my luck (or boring bar) so my reamer only has a minimal cut to make.

What makes this step more challenging, is that I chamber any and everything. If I only chambered 308 w, I would be more comfortable with the boring step. But, I don't have that luxury, so i have several different twist drills and boring bars I use now, with layout dye and scratches on them.

All this said, I do not chamber first, but I probably should after I think this through to conclusion....because in the event I cut too deep with my boring bar, I could easily clean up the chamber by running the reamer deeper. If the threads, cone etc are already established, this would be a pita, but not the end of the world....

I'll have a think about it for my next barrels.

Ben
 
Jackie, as you know I do the tenon first. I can only count 6 years in the machine shop. It appears that we are cutting fine hairs here again. Since I don't have your experience and knowledge and still don't understand, I think I will not change. I am not questioning your methods, I just don't see any advantage of changing that part of the operation.
Butch
 
JerrySharrett said:
Joe, for God's sakes be careful. Make sure what you are doing before turning a spindle on. I was in the shops for 40 years. I saw one guy get his arm torn off leaving a chuck wrench in a chuck on a Monarch EE that was set for about 3,000 rpm. Saw a few fingers torn off too. Remove your finger rings, watches and long sleeve shirts.

I have been scared to death a few times too in the 8 years I spent teaching evenings Machine Tool Technology and Manufacturing Engineering Technology at a local community college. It is very easy to get seriously injured with a machine tool.

They say the good Lord takes care of fools and idiots. Must be why I'm still here!!
Click to expand...

Yes the good Lord does take care of fools and idiots but not on this earth .
 
Cutting the barrel

Taking the risk of asking a dumb question. :eek: In all this dissertation on setting up both ends of the barrel, little was said on cutting to length. Butch remarked that he cut 1 1/2 inches off the chamber end and 1 inch off the muzzle end "initially". At what point do we determine the final length and cut the barrel to this dimension? Any particular rules or guidance?
 
Adam

When dealing with a barrel intended to go on a Benchrest Rifle, the predominate factor in determining where to cut it is what will make weight. This esspecially holds true for LV and Sporter.

For instance, on my Sporters, which have a 5.5 ounce tuner attached, I have to cut the barrel far enough down the taper so as to end up with about a 77 ounce barrel at 21 1/4 inches..........jackie
 
adamsgt said:
Taking the risk of asking a dumb question. :eek: In all this dissertation on setting up both ends of the barrel, little was said on cutting to length. Butch remarked that he cut 1 1/2 inches off the chamber end and 1 inch off the muzzle end "initially". At what point do we determine the final length and cut the barrel to this dimension? Any particular rules or guidance?
Click to expand...

Good question..

Tim North (broughton bbls) marks with a sharpie how much comes off the muzzle. The breech is up to you. I usually face the breech back 1/2" or so, depending on bbl contour and use sometimes I cut 2" off the breech to adjust weight. For instance, I needed a 27" #8 contour Krieger, and Brunos had a 30" LV, so I cut the breech back and muzzle back and kept the middle.

On benchrest bbls I was told 1-1.5" off muzzle. This is what I have been cutting of Krieger and Shilen bbls.

Most bbls have a contour finished length chart, that is a good guide as well.

http://www.kriegerbarrels.com/Contours-c1246-wp3382.htm

I cut (parting tool) to final length indicate the crown and breech with a indicator rod or dial indicator and cut crown, first thing...then set up the breech and face it off at high speed with a sharp tool..
 
I'm sure that most of us have varied our techniques over the years. I know I do things differently than I did 30 years ago. If I did not, that would indicate that I am obstinate and incapable of learning. Both of these assertions I deny! Stubbornly!
The last barrel I put on (yesterday) was a hammer forged barrel in which the chamber was forged along with the rifling (btw, that chamber is perfect. It's round, it's concentric, and it's beautifully smooth). Although the material was nearly 1 3/8" diameter over the chamber, I could see no evidence of distortion. Tough steel BTW. Regards, Bill.
 
adamsgt said:
Taking the risk of asking a dumb question. :eek: In all this dissertation on setting up both ends of the barrel, little was said on cutting to length. Butch remarked that he cut 1 1/2 inches off the chamber end and 1 inch off the muzzle end "initially". At what point do we determine the final length and cut the barrel to this dimension? Any particular rules or guidance?
Click to expand...
According to what you are fitting a barrel for there are several things to consider. For example, chambering a barrel for a hunting or 600/1000 guns you are very much interested in finish length and not necessarily weight.

On a 100/200 benchrest rifle where weight is a limiting factor, hopefully you have the old barrel that is the correct weight. If so, just duplicate it. Measure the chamber end diameter and if the to be chambered barrel is the same diameter (1.200 or 1.250") just measure the straight section, then measure the overall length, then at that point, measure the new barrel diameter at that distance. If these all agree, just have at it.

For a new build, things get more touchy. I use Dan Lilja's BASIC program from his web site. Quite a program. Dan also has a more modern Windows program but I can never get the weight right with it.

Things to consider on barrel weight;
1-A short stubby barrel that weighs the correct amount (eg 5# 2oz) will stay in tune over a wider window than a longer more limber barrel weighing the same amount.

2-If you go for the shorter stubby barrel, later setting back the barrel to refresh it may be more difficult since you will be taking more weight off per inch of barrel than a long limber one. This may make the barrel harder to set up on the bench since you are having to set the gun forward more to start with.

Some examples;

A fiberglass McMillan stock, a Leupold Competition scope, a Panda action, a barrel probably can't weigh over about 4# 12 oz.
A wood custom stock (Terry Leonard), LCS scope, Panda action, the barrel can go up to about 5# 4 oz.

later

One more comment. Some shooters have a "magic" length, say 21-3/4" or whatever. There ain't no magic length. Too many variables like steel composition, barrel heat treat condition, etc.

All the above is said to where you are trying to stay within the 10-1/2 pound limit for LV and Sporter classes primarily.

And above all, remember Uncle Ross (Perot) said, measure twice, cut once!!! Now if I could just remember what he said about NAFTA and GATT???
 
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