A couple of questions

[Greg Walley]

?

Boyd Chamber run out in the zero is always a good thing. It is possible to have zero chamber run out and still be as much as .010 off center of the true bore. Chamber alignment to true bore axis is very important. It is what is needed to have the bullet start .0001 or less to the true bore axis.
At least that is what I like to think.

Chet

I'm not sure how one could have 0.010" at the throat, and no runout at the chamber if the centers were cut into the barrel bore properly. Maybe if a floating reamer holder were used it would end up that bad. I don't think I've ever seen one more than 0.001" FIM...even on the Ultra Mag and Lapua Mag cartridges.

 

[B.Larson]

i find it strange, that when jerry says something contrary to this thread, its just fine, but not when i do.
i find it strange that so called "gunsmiths" have little common sense when it comes to using a lathe.

i do not need your participation trophy..i have a first in 1000 yd with the rifle i chambered jackie's way and a 4th in the state...ohh that all occurred in all of 4 matches.
i know i know little about 1000 yd wind reading ...but the rifle shoots.

you see i was ___"SMART"___ enough to buy a lathe i could use for chambering, i did not buy a lathe and then try to figure out how i could chamber with it.

next time try posting something productive...you know sort of like an adult, your behavior here is not what i have come to expect from br shooters.....

Mr.Stool........ I believe your fire damaged more than machinery....carbon monoxcide causes permanent brain damage......... Yet you describe yourself as being "SMART"..... ???????
As geo U. and G.Walley and Mcmillans and myself.... desrcibe another way....
When you get your smart lathe up and running...... let us know.....try some different set-ups....it will open your eyes...and not your mouth....
bill larson

 

[Greg Walley]

Respectfully disagree

Boyd, pay attention to the video. The indicator stylus ball is running on the chamber base mostly (some of the chamber body, maybe). At that point it can only show one of two things:

1) It can show out of roundness of the chamber. You would be surprised how many chambers are out-of-round.

2) It can show if the chamber base is not running concentric with the turned journal that the steadyrest is running on.

It, however, does not show ANYTHING about the o most critical area of the installed chamber, the relationship of the merger of the chamber neck/leade with the barrel bore at that point!!!!!!!!!!!!!!!!!!!!!!!!!!

Here are results with my method at "the most critical area" referred to by some of the contributors to this thread. Again, it is a fallacy to state that good alignment and concentricity can’t be achieved with the steady rest used in the conventional manner… provided the centers are reamed or machined properly before machining and reaming the tenon and chamber.

Throat – 0.0003” FIM: http://youtu.be/ebUDKN2MM4I

Chamber rear – 0.0001” FIM: http://youtu.be/O7RuHRXiUZQ

Tenon shoulder – <0.0001” FIM: http://youtu.be/piNKk749WtQ

 

[JerrySharrett]

Here are results with my method at "the most critical area" referred to by some of the contributors to this thread. Again, it is a fallacy to state that good alignment and concentricity can’t be achieved with the steady rest used in the conventional manner… provided the centers are reamed or machined properly before machining and reaming the tenon and chamber.

Throat – 0.0003” FIM: http://youtu.be/ebUDKN2MM4I

Chamber rear – 0.0001” FIM: http://youtu.be/O7RuHRXiUZQ

Tenon shoulder – <0.0001” FIM: http://youtu.be/piNKk749WtQ

Greg, what I wrote was "All I am saying is that the most near-prefect alignment that can be obtained would be with the chambering through the headstock method....."

The 0.0003" at the throat is a bunch and can cause some in-bore yaw. I don't really care if the tenon shoulder is 0.0001 and the chamber rear is 0.0001". This has nothing, or an insignificant effect, on bullet presentation and in-bore yaw!!

 

[Greg Walley]

The 0.0003" at the throat is a bunch and can cause some in-bore yaw. I don't really care if the tenon shoulder is 0.0001 and the chamber rear is 0.0001". This has nothing, or an insignificant effect, on bullet presentation and in-bore yaw!!

Jerry,

I guess we will just have to agree to disagree on that one. If the concentricity were that critical, then I should throw my barrels away after 100 rounds. The throat concentricity from the top of the lands to the bottom of the grooves of the barrel in this video measured about as close to zero as my indicator would read when it was unfired (rotating the barrel in a V-block with the shoulder of the tenon stopped on the face of the block).

http://youtu.be/G7wa0_ys-Is

FIM is 0.0003, therefore the TIR 0.0003/2 = 0.00015.

The bullets aren’t made nearly that well.

 

[B.Larson]

why would i waste my time????
why learn to waste time ?
jackie's method works and takes less time.
are you stating that the headstock bearing is not the most precise bearing on a lathe ??

simple question were you a trained machinist that became a gunsmith, or did you learn to use a lathe as part of gunsmithing ??

i see, you too, have lowered your personal standards.....

STOOL (? CAN ONLY GUES AT YOUR first NAME )
Worked as a machinist before volunteering ( 4 YRS.) for the service during the Viet Nam War.....Trained as a machinist in the United States Navy...52 weeks.....made a living at it for 50 years...worked in R&D for 25 yrs. with people who had masters degrees in the mechanical field......some when you take them away from the keyboard they were handcuffed.....SMART AT THE KEYBOARD...KNEW IT ALL ( sound filmilar ??)
I have had a 2 lathes 2 mills etc.etc ( all operate )....in workshop for 15 yrs...I .build about a gun a month.... mainly for LR shooting..I shoot competitively 4 disciplines.LR "F" class (600-1400yds,),high power silhouette (200-500M),SR benchrest 100yds.Barnyard br 50yds.......how do you chamber a 32" long barrel
Now you called yourself SMART....but with LIMITED EXPIERIENCE... ( Your Words )...what kind of FORMAL training have you HAD to form your opinions...???

bill larson

 

[Gene Beggs]

Interesting!

Guys I think someone down there in the Houston area is 'pullin' our leg,' 'rattlin' our chain' or whatever you want to call it. Mr Stool is just having fun. Let's see if we can figure out who he is; what do you say?

First, if he is being schooled by Jackie Schmidt, he must live in or around Houston. Jackie, are you masquerading as "Stool?" Huh? That would be just like you you rascal you. Let's see now, who else do we know down there in the Houston area? The search is on!

Gene Beggs

 

[sdean]

Sounds like the same guy that got run off from here last year. Just a guess. Must be ashamed of his real name.
My name is Stephen Dean

 

[coyotechet]

I'm not sure how one could have 0.010" at the throat, and no runout at the chamber if the centers were cut into the barrel bore properly. Maybe if a floating reamer holder were used it would end up that bad. I don't think I've ever seen one more than 0.001" FIM...even on the Ultra Mag and Lapua Mag cartridges.

Greg where in my post above did I say any thing about run out at the throat . And I was not saying anything about your work or set up I was only saying that one could cut a chamber with zero run out and still not be true the axis of the bore. Maybe .010 little much but I have seen a lot more then a .001 when the barrel is checked out after words using the head stock system to find the T.I.R. of .0001 or less at the throat and then checking the run out at the chamber end. No way am I going to say what is the best way. I just was saying what was possible and how I do it. I truly am sorry if I made you or anyone feel that I was talking about your work or setup.
Have a great day and see ya that the shoot.
Chet

 

[JerrySharrett]

Jerry,

I
http://youtu.be/G7wa0_ys-Is

Besides, the cosine error on the indicator reading of my Mitutoyo #513-504 with the stylus 3° off centerline, is 2.5x greater (verified on a plate with gage blocks). Therefore the TIR (0.0003/2.5)/2 = 0.00006.

The bullets aren’t made nearly that well.

Greg, I could live with 60 mil but not 0.0003". (0.0003/2.5)/2 is TIR???


Edit

The throat concentricity from the top of the lands to the bottom of the grooves of the barrel in this video measured about as close to zero as my indicator would read when it was unfired (rotating the barrel in a V-block with the shoulder of the tenon stopped on the face of the block

I'm not talking about max-to-min (grooves to lands) concentricity, I am talking about concentricity of the groove diameter to the freebore diameter (the leade area)

 

[Greg Walley]

Greg where in my post above did I say any thing about run out at the throat . And I was not saying anything about your work or set up I was only saying that one could cut a chamber with zero run out and still not be true the axis of the bore. Maybe .010 little much but I have seen a lot more then a .001 when the barrel is checked out after words using the head stock system to find the T.I.R. of .0001 or less at the throat and then checking the run out at the chamber end. No way am I going to say what is the best way. I just was saying what was possible and how I do it. I truly am sorry if I made you or anyone feel that I was talking about your work or setup.
Have a great day and see ya that the shoot.
Chet

Very good Chet. I know that you weren’t inferring anything – and my statement wasn’t rhetorical just to question your experience. I’m only wondering how these chambers can become so “whopperjawed”. If the machining setup and the features of the imperfect bore are dealt with appropriately, one shouldn’t see such gross alignment issues. See you at the FISS.

 

[Greg Walley]

Greg, I could live with 60 mil but not 0.0003". (0.0003/2.5)/2 is TIR???)

I edited my miscalculation in the above post. That particular indicator reads without error with the stylus in that position. I was thinking of another indicator in my collection.
My understanding is that TIR is one-half of the value of the total movement of the stylus around the circumference of the bore, since we are dealing with a radius from the center point of the bore.

 

[Greg Walley]

I'm not talking about max-to-min (grooves to lands) concentricity, I am talking about concentricity of the groove diameter to the freebore diameter (the leade area)

I’m not talking about that either. What I’m measuring is the freebore straight section and also the leade cut by the reamer.

I respectfully disagree with you. The chamber roundness and its axial relation to the shoulder of the tenon and the threads are important for several reasons…mainly a better chance to have chambers that are consistent in size and will be square/perpendicular to the boltface.

What I’ve done in the video example is given a reference datum to the freebore that can be monitored throughout the life of the barrel. My conclusion is I’m not sure it really matters that much. Your effort in machining this surface to such exacting tolerances ends up being quickly eroded away. It would be like setting up a job for jig-grinding and dialing in the feature to be ground to the gazillionth of an inch, then cutting the hole with a plasma cutter. In my experience, as long as the piloted reamer is guided by the bore (top of the lands) in a in a true condition, the chamber will be acceptable.

Again – I don’t mean to suggest that one shouldn’t take the appropriate steps to do the job to the best of one’s ability…only that many are barking up the wrong tree trying to theorize how well a barrel will shoot based on how the bullet starts in the throat with very tiny imperfections...that will be overcome and lost in the noise by more grotesque imperfections throughout the rest of the barrel.

 

[JerrySharrett]

......, as long as the piloted reamer is guided by the bore (top of the lands) in a in a true condition, the chamber will be acceptable.

Again – I don’t mean to suggest that one shouldn’t take the appropriate steps to do the job to the best of one’s ability…only that many are barking up the wrong tree trying to theorize how well a barrel will shoot based on how the bullet starts in the throat with very tiny imperfections...that will be overcome and lost in the noise by more grotesque imperfections throughout the rest of the barrel.

The reamer being guided by the lands instead of the grooves is a potential accuracy problem that would be very very difficult to address since the bullet/barrel interface is effected mostly by the grooves.

Shortrange benchrest may not require as perfect a fit of bullet/barrel merger as longrange does but:

The known fact that some barrels shoot better than others is not totally dependent on the barrels physical properties, heat treatment, stresses, concentricity, cyindricity of lands to grooves, and such but that most desired trait is influenced by how perfect the bullet starts down the barrel.

 

[JerrySharrett]

I edited my miscalculation in the above post. That particular indicator reads without error with the stylus in that position. I was thinking of another indicator in my collection.
My understanding is that TIR is one-half of the value of the total movement of the stylus around the circumference of the bore, since we are dealing with a radius from the center point of the bore.

TIR, is the acronym for Total Indicator Runout (or Reading as some of the older guys call it).

 

[Gene Beggs]

Lively and very interesting thread!

'Lucky Shooter-A. Weldy'

Allan, your thread drifted off subject somewhat but in my opinion, it developed into one of the most interesting and informative seen on the forum in a long time! I've enjoyed it immensely.

Many thanks to the professionals (and you know who you are) for sharing your knowledge and experience with us amateurs. Believe me, it is greatly appreciated!

Gene Beggs

 

[Lucky Shooter A]

You're right Gene

This has been something else.

I've heard the expression----"a gathering of eagles"------and that is what we have here.

I think I'm beginning to see where we're moving from a "how to do it" discussion into a discussion on defining the "requirements" of a good chamber----followed by "how to do it to meet these requirements".

Disagreements among experts is very common but all still remain experts----our experts respectfully disagree and their barrels continue to be good shooters.

I've personally bought in on the "throat/muzzle alignment" method-----not necessarily because its absolutely the best way to go but because its simple enough that a green guy can do it---and---because every barrel I've done this way has been a good shooter. I'm open to change but haven't see a reason to change.

A. Weldy

 

[B.Larson]

Real Name

Sounds like the same guy that got run off from here last year. Just a guess. Must be ashamed of his real name.
My name is Stephen Dean

+2............ after checking.....there are some stools listed in the Houston area......
my real name is.........
bill larson

 

[coyotechet]

Very good Chet. I know that you weren’t inferring anything – and my statement wasn’t rhetorical just to question your experience. I’m only wondering how these chambers can become so “whopperjawed”. If the machining setup and the features of the imperfect bore are dealt with appropriately, one shouldn’t see such gross alignment issues. See you at the FISS.

You are so correct and not very body as the machining ability as you including myself that is why I do it thru the headstock. Also I bet you cut more chambers in a month then I have or will in my life time.
Thanks and cya at the shoot Chet.

 

[Dan H]

Hey Greg,

You have a message

Dan