Jackie chambering a Barrel (Pictures)

Each picture is worth a thousand words

Jackie

The step by step series of pictures tell what words alone can't and shows exactly, in a no nonsense way how, a machinist chambers a barrel.

Thanks for providing the best write up on chambering.

PS
As someone stated before this valuable piece of information needs to be made a sticky.

Hal
 
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Questions regarding details of Jackie Schmidt's chambering method

My questions are for Mr. Jackie Schmidt.

After drilling and boring the chamber end of barrel the reamer is then inserted and a final .003" is reamed to finish the chamber. Question is: What about the throat and neck portion of the reamer? Where and when do they engage the bore? Does the body of the reamer engage the walls of the newly bored barrel before the throat portion of the reamer begins to cut? If this is so, then I can see that there will be good alignment of reamer with chamber. If not then the throat portion will engage first and what will guide it to center of bore? Mr. Schmidt, do you also pre-bore the neck/throat area?

Seems to me that if the throat end of reamer engages first then the cutting will be guided by the lands and groves. Whatever their geometry (good or bad) will guide the reamer for this very important area of chamber. And after the remainder portion of the reamer engages the pre-bore area the reamer will stabilize and the throat/neck area will be ok or maybe oval shaped.

I am preparing to bore my first barrel and these issues perplex me. Thank you very much for your help Mr. Schmidt.
 
tDarragh said:
My questions are for Mr. Jackie Schmidt.

After drilling and boring the chamber end of barrel the reamer is then inserted and a final .003" is reamed to finish the chamber. Question is: What about the throat and neck portion of the reamer? Where and when do they engage the bore? Does the body of the reamer engage the walls of the newly bored barrel before the throat portion of the reamer begins to cut? If this is so, then I can see that there will be good alignment of reamer with chamber. If not then the throat portion will engage first and what will guide it to center of bore? Mr. Schmidt, do you also pre-bore the neck/throat area?

Seems to me that if the throat end of reamer engages first then the cutting will be guided by the lands and groves. Whatever their geometry (good or bad) will guide the reamer for this very important area of chamber. And after the remainder portion of the reamer engages the pre-bore area the reamer will stabilize and the throat/neck area will be ok or maybe oval shaped.

I am preparing to bore my first barrel and these issues perplex me. Thank you very much for your help Mr. Schmidt.
Click to expand...


A typical PPC or BR reamer has a little over .008 total taper in the bodies length. The .003 to .004 that I leave to allow the reamer to finish the chamber's body allows the reamer to go in just past 1/2 way befor it starts cutting.

At that distance, the pilot does engage the indicated lands and grooves, but the reamer has not contacted the neck and throat portion as of yet.

You have to be very meticulous in your boring of the taper, being sure that your compound is indeed cutting the exact taper as the reamer body.

Also, be very meticulous when you reach in and indicate the lands and grooves after rough drilling. The entire purpose is to insure that what your reamer cuts will be truly straight with that portion of the barrel.

In the end, you should have 3 points that run dead true. The muzzle, the lands and grooves just forward of the throat, (that first thing the bullet "sees", and the chamber.
 
Thanks to Mr. Schmidt

Thank you very much. I understand your answer. Very clear.

One miss-understanding I had was the .003" of stock removal by reamer. It is now clear that you are talking about diameter not length. My bad. And that you do use a pilot. Do you use a loose fitting pilot or snug? I have been told that best is at least .0002" less than id of bore.

Also, do you bother to clock barrel where muzzel end is pointing up?

Tom D.
 
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Jackies method the muzzle is already inline with the indicated throat and chamber. No clocking or indexing of the barrel unless you use Gordys method of indicating the first few inches and let the muzzle runout. Hope this helps
 
ummm,..... chamber, lands and grooves, and muzzle aligned.....when? Before the chamber is cut or afterwards????????? Seems the only way to achieve those 3 points of alignment before, is to bend the barrel. If achieved afterward then the chamber would be bored on a cant, by starting with the muzzle and the bore ahead of the throat in alignment, (2) points,...... and after you ream then you pick up the third.
 
More on indexing barrel

Thank you for your help Mr. Doane. Being that all barrels will have at least some curve in them, I asked the question. I understand the straight line thru the three points. However there will still be a curve existing between the throat "point" and the muzzle end "point." Seems this is of no consequence if Mr. Schmidt's method is followed. I only wanted to make sure.

Regarding post by TRA, third point in line (chamber) would be acquired after boring chamber, is what I believe Mr. Schmidt is saying. No barrel bending required. ?

Tom D
 
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tDarragh said:
Thank you for your help Mr. Doane. Being that all barrels will have at least some curve in them, I asked the question. I understand the straight line thru the three points. However there will still be a curve existing between the throat "point" and the muzzle end "point." Seems this is of no consequence if Mr. Schmidt's method is followed. I only wanted to make sure.

Regarding post by TRA, third point in line (chamber) would be acquired after boring chamber, is what I believe Mr. Schmidt is saying. No barrel bending required. ?

Tom D
Click to expand...

That's how it sounds to me. The chamber and the tenon is canted with relationship to the barrel to align up with the muzzle.
 
Whether the "Gordy's" method is used or the "Jackie's" method is employed, both seem to provide very accurate rifles. Not having to clock the curve in barrel to a certain location is what I like. Less work. I will dive in and do my very first chamber very soon. Excitement is building.

My particular cartridge is .284 Winchester. There seems to be no difference in the process, whether the cartridges be long or short.

Thank you to everyone who is helping bring to light the details of how to do these projects.


Tom D.
 
trying to indicate the throat of a long cartridge can be a challenge.

tDarragh said:
Whether the "Gordy's" method is used or the "Jackie's" method is employed, both seem to provide very accurate rifles. Not having to clock the curve in barrel to a certain location is what I like. Less work. I will dive in and do my very first chamber very soon. Excitement is building.

My particular cartridge is .284 Winchester. There seems to be no difference in the process, whether the cartridges be long or short.

Thank you to everyone who is helping bring to light the details of how to do these projects.


Tom D.
Click to expand...
 
All this talk of barrel bore curve. Do you mean when holding a barrel the bore might start in the center and takes an arc, spirals, curves and straightens out. I believe a lot of folks have heard this term, barrel bore curve, but have not a clue what the barrel bore is really doing. If you don't know, how do you fix it?
 
tDarragh said:
Thank you for your help Mr. Doane. Being that all barrels will have at least some curve in them, I asked the question. I understand the straight line thru the three points. However there will still be a curve existing between the throat "point" and the muzzle end "point." Seems this is of no consequence if Mr. Schmidt's method is followed. I only wanted to make sure.

Regarding post by TRA, third point in line (chamber) would be acquired after boring chamber, is what I believe Mr. Schmidt is saying. No barrel bending required. ?

Tom D
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That is correct.

Machine shop practice dictates that if you wish to establish three true points one a piece that is not true, what you have to do is indicate two predetermined points and machine the third point true with those two points. That is the best you can hope for.

If you have monitored this Forum for any length of time, the big argument, when dealing with the ID of a barrel, has always been which two points do you indicate before machining the chamber, threads, and other operations.
 
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Bore straightness

Butch Lambert said:
All this talk of barrel bore curve. Do you mean when holding a barrel the bore might start in the center and takes an arc, spirals, curves and straightens out. I believe a lot of folks have heard this term, barrel bore curve, but have not a clue what the barrel bore is really doing. If you don't know, how do you fix it?
Click to expand...


Regarding straightness of bore, whether it curves this way or that way, it is a fact that perfectly straight bores don't exist. And cannot be corrected (to perfection). We as mortals work with what we have and can achieve. Our process is to get as close to perfection as possible, as I believe that Jackie Schmidt has stated in so many words. If we can do something to get closer to that perfect condition, in the benchrest world, we will.

I like the methods that are described here for dealing with what we have (crooked barrels). A pretty straight chamber, lined up with a not perfectly straight bore, is about the best that can be achieved. Very accurate rifles are made with these methods, (even with these crooked barrels).

I don't particularly care if a barrel bends this way or that way. If it shoots good who cares? The clocking idea is something that has come up and I am trying to determine if this is important. Some barrels seem to have a definite curve in them, like a bow.


Tom D.
 
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If you do indicate the first few inches of the chamber end and do your work the muzzle will runout. Indexing the muzzle does not have to be done for the barrel to be accurate. Some clock it up or down and others don't even bother checking it. Hope this helps
 
tDarragh said:
Regarding straightness of bore, whether it curves this way or that way, it is a fact that perfectly straight bores don't exist. And cannot be corrected (to perfection). We as mortals work with what we have and can achieve. Our process is to get as close to perfection as possible, as I believe that Jackie Schmidt has stated in so many words. If we can do something to get closer to that perfect condition, in the benchrest world, we will.

I like the methods that are described here for dealing with what we have (crooked barrels). A pretty straight chamber, lined up with a not perfectly straight bore, is about the best that can be achieved. Very accurate rifles are made with these methods, (even with these crooked barrels).

I don't particularly care if a barrel bends this way or that way. If it shoots good who cares? The clocking idea is something that has come up and I am trying to determine if this is important. Some barrels seem to have a definite curve in them, like a bow.


Tom D.
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Tom,
I think you misinterpreted my post, or maybe I was not clear. I agree that bores are not straight. I also state that bores do not have a banana shape.
 
Hillbilly said:
If you do indicate the first few inches of the chamber end and do your work the muzzle will runout. Indexing the muzzle does not have to be done for the barrel to be accurate. Some clock it up or down and others don't even bother checking it. Hope this helps
Click to expand...

I agree!
 
I got it

Butch Lambert said:
Tom,
I think you misinterpreted my post, or maybe I was not clear. I agree that bores are not straight. I also state that bores do not have a banana shape.
Click to expand...


Hi Butch, I think I understood what you said. Sorry my response did not express that. I very much appreciate your input. I have been watching the threads and discussions that you and others post for awhile now.

I understand that gun drills will follow the path of least resistance. Barrel bores could be "s" shaped or "spiral" shape, I suppose. One thing for sure is that they will not be perfectly "straight" shaped. I think your point is that we can do nothing about how straight our particular barrel is and that we just live with what we got and that barrel unstraightness is not a big deal. Correct?

I suppose that barrels aren't banana shaped. Portions of it will be, I am sure. When the chamber end of a barrel is indicated in, at times, it sure appears that it might be banana shaped.

Anyway, thank you very much for your help sir.


Tom D.
 
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Hmmm

Hillbilly said:
If you do indicate the first few inches of the chamber end and do your work the muzzle will runout. Indexing the muzzle does not have to be done for the barrel to be accurate. Some clock it up or down and others don't even bother checking it. Hope this helps
Click to expand...


Interesting. Two theory's. Each are verifiably good methods. Eeny meeny miney mo. Or spin the bottle. My tooling set I have on hand will probably dictate which will work for me. My first time to cut a chamber. My biggest concern is starting and keeping my reamer straight.
 
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