• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

Why do we get fanatical over barrel alignment?

Sure. It's about minimizing the things we don't want. If there's a better way to get a concentric throat, I'd like to know about it.
Ever scoped a bbl that indicated perfectly but the lands vs grooves appear to be less than perfect? If you've done more than a few, of course you have. The trig is minor, relatively speaking but bore scopes show it all. You can and will have one be perfect but the other, not. Absolutely NO way to have both perfect unless both are perfectly concentric to one another. We must first realize and admit that there is no such thing as "perfect" and then learn what we can accept. There are varying degrees of F'd up but perfect died for us all. The end.
 
Ever scoped a bbl that indicated perfectly but the lands vs grooves appear to be less than perfect? If you've done more than a few, of course you have. The trig is minor, relatively speaking but bore scopes show it all. You can and will have one be perfect but the other, not. Absolutely NO way to have both perfect unless both are perfectly concentric to one another. We must first realize and admit that there is no such thing as "perfect" and then learn what we can accept. There are varying degrees of F'd up but perfect died for us all. The end.

Yep.
 
Another thing is that I cringe a bit when people claim to bore to the same angle as the chamber, when chamber reamer makers only guarantee +/- 1/4 of a degree. Do the math on that. Frankly, might as well bore it straight. Grrr. Shooting forums are not the place to learn precision machining, overall. I can't even get people to realize that a 7/8-32 thread is not .875 finished! It's machining 101 and it's all covered in Machineries Handbook. Chambering is really basic machining. Even moreso than threading but we do add a twist when we want perfection from a crooked tube with two different ID's.
 
Exactly right and exactly what most shooters SHOULD worry about. Anyone that doesn't understand that even a high end lathe has more runout from the FACTORY than what most internet posters EXPECT, should really focus on things that matter the most to their results. Let the smiths split those other hairs. I have trouble when smiths or anyone else starts splitting tenths, when they are self taught with a basement lathe. Sorry, but true.
I'm sure some Smith's went to some Machinist School or were trained in a machine shop, But to say that self taught Gunsmiths are any less isn't fair at all, There are many top Smiths that taught themselves, And there are many shooters that do their own work and do very good work.
 
I
Another thing is that I cringe a bit when people claim to bore to the same angle as the chamber, when chamber makers only guarantee +/- 1/4 of a degree. Do the math on that. Frankly, might as well bore it straight. Grrr. Shooting forums are not the place to learn precision machining, overall. I can't even get people to realize that a 7/8-32 thread is not .875 finished! It's machining 101 and it's all covered in Machineries Handbook. Chambering is really basic machining. Even moreso than threading but we do add a twist when we want perfection from a crooked tube with two different ID's.

I never understood taper boring. Seems like extra work for the same outcome. I have a carbide reamer that prefers if I step bore the very start of the chamber, otherwise it squeals like worn brake pads.
 
I'm sure some Smith's went to some Machinist School or were trained in a machine shop, But to say that self taught Gunsmiths are any less isn't fair at all, There are many top Smiths that taught themselves, And there are many shooters that do their own work and do very good work.
Oh, trust me on this. There are many very good self taught gunsmiths that overlooked or never learned some very basic aspects of machining. I'm not exaggerating at all, nor am I disrespecting some really good self taught smiths. If your smith can't positively thread ANYTHING to a print, including class of fit, he can still cut a very good chamber, but is not a machinist. Self taught is just that. Not good nor bad. There are some very respected smiths who don't own wires or thread mics, but thread everything "to fit". This works most of the time but threads haves classes for a very specific reason. A smith that doesn't have or use wires or thread mics can still chamber a good bbl but they are creating thir own class of fit in regard to threads and that's that. Nothing more to it.
 
Another thing is that I cringe a bit when people claim to bore to the same angle as the chamber, when chamber reamer makers only guarantee +/- 1/4 of a degree. Do the math on that. Frankly, might as well bore it straight. Grrr. Shooting forums are not the place to learn precision machining, overall. I can't even get people to realize that a 7/8-32 thread is not .875 finished! It's machining 101 and it's all covered in Machineries Handbook. Chambering is really basic machining. Even moreso than threading but we do add a twist when we want perfection from a crooked tube with two different ID's.
Have you ever seen the stuff that Jackie Schmidt machines? The dude has a Lathe that looks like it's 30 feet long and he machines parts as big as a house, He's a great machinist and a great shooting competitor, I think what it boils down to is everyone has a way of doing things that they think is the right way, And most of them will produce excellent results.

My old boss and still a good friend to this day, Is one of the most talented machinist's I've ever seen, He Is self taught, He has been in many hot rod magazines and machines very intricate and complex parts for hot rod engines, He has never worked in any machine shop but his own.
 
Have you ever seen the stuff that Jackie Schmidt machines? The dude has a Lathe that looks like it's 30 feet long and he machines parts as big as a house, He's a great machinist and a great shooting competitor, I think what it boils down to is everyone has a way of doing things that they think is the right way, And most of them will produce excellent results.

My old boss and still a good friend to this day, Is one of the most talented machinist's I've ever seen, He Is self taught, He has been in many hot rod magazines and machines very intricate and complex parts for hot rod engines, He has never worked in any machine shop but his own.
I never said anything about Jackie, good or bad. I simply stated facts. I'm not even sure where or why you're disagreeing with them. Nor am I disagreeing with your friend's abilities, which I'm only now being made aware of. This isn't personal in any way.

I worked in a shop similar to Jackie's when I got out of high school. Big only means bigger tolerances...and it's heavier. The print is what determines how precise anything has to be in a job shop. I'm not knocking him in any way and big parts certainly do present their own challenges. Clearly, you've never worked in this field, though. That's not a putdown, just a statement of what I believe is true because of your posts.

Nevertheless, I'm still not sure where we disagree. My point was strictly about thread classes and fitment. I even said that someone can still chamber a good bbl without regard to them, but they are creating their own class of fit.

Not wanting to argue so please help me see what I said that is untrue in any way or lets move on.
 
You can take the slack out of the grizzly rod. Then the only slack you have is whatever oil you have between your surfaces.

Pre-bore is the way to go. Even if your tool has some deflection... so what. The hole size doesn't matter, as long as it's perpendicular to your throat.

The Grizzly rod works most of the time. I was forced to make the switch to all Interapid all the time when I couldn't get any consistent reading from the rod in a particular barrel. I have found that when I have the Interapid to within .0002, and I check it with the Grizzly, the Grizzly shows zero. I don't think we can get all the play out of the Grizzly, but we can get very close.

As to preboring, the potential issue I see is that the alignment must be perfect between the prebored hole and the pilot entering the throat area. If it is off then the reamer is cutting in a bind. Floating reamer holders like the JGS are designed to allow for slight misalignment, but if the back of the reamer isn't aligned with the front of the reamer when the pilot enters the throat, then the reamer will have to absorb that by flexing and/or cutting oversized.

By using the reamer for the whole chamber, it follows whatever path the bore takes very smoothly and when the pilot reaches the throat everything is fully supported and aligned.

At least that's my thinking right now and I reserve the right to continue to refine and modify my process. In reality, I think it's so easy to get the first 3" or so straight that there won't be much difference in either method.
 
Preferences:

If I were having a rifle built, I'd prefer the work of a journeyman
machinist over a guy who calls himself a gunsmith and who has
limited machine skills.

I have a shooting buddy who is a retired machinist. He goes about
gun stuff with no wasted motion or standing around trying to figure
out what to do next.

My hat's off to good machinists.

A. Weldy

I wouldn't throw non-machinist, self-taught guys completely under the bus. The pics below are 1000 yd BR targets with a 2.75" X-Ring, shot in competition during a 1000 yd BR match. There are many of us who do our own work, are self-taught, and then prove our work in competition.

50AF42AC-A9E7-4BAB-B6C8-69D99CB37215.jpeg
FD2C7C0F-07D7-414B-85F4-61B1C897554D.jpeg
 
I wouldn't throw non-machinist, self-taught guys completely under the bus. The pics below are 1000 yd BR targets with a 2.75" X-Ring, shot in competition during a 1000 yd BR match. There are many of us who do our own work, are self-taught, and then prove our work in competition.

View attachment 1370693
View attachment 1370694
Very very few of the gunsmiths on the match reports were ever machinists.
 
Very very few of the gunsmiths on the match reports were ever machinists.
One doesn't have to be a machinist to chamber a match winning barrel Dusty you are correct.if all the machining is done to spec and the chamber is concentric and true is right and right is right no matter who does it.thats no disrespect to anyone.where a machinist scores is when presented with more intricate jobs and that isn't always fitting a rifle barrel.
 
I never said anything about Jackie, good or bad. I simply stated facts. I'm not even sure where or why you're disagreeing with them. Nor am I disagreeing with your friend's abilities, which I'm only now being made aware of. This isn't personal in any way.

I worked in a shop similar to Jackie's when I got out of high school. Big only means bigger tolerances...and it's heavier. The print is what determines how precise anything has to be in a job shop. I'm not knocking him in any way and big parts certainly do present their own challenges. Clearly, you've never worked in this field, though. That's not a putdown, just a statement of what I believe is true because of your posts.

Nevertheless, I'm still not sure where we disagree. My point was strictly about thread classes and fitment. I even said that someone can still chamber a good bbl without regard to them, but they are creating their own class of fit.

Not wanting to argue so please help me see what I said that is untrue in any way or lets move on.
Clearly I have never worked in what Field? I worked under my self taught machinist friend in his shop doing nothing but barrel work. And I have my own home machine shop in which I have created several inventions, Did my own Patent work for them and The US military has used them. I am self taught, I don't need a title. I do my own rifle work for myself.
 
As to preboring, the potential issue I see is that the alignment must be perfect between the prebored hole and the pilot entering the throat area. If it is off then the reamer is cutting in a bind. Floating reamer holders like the JGS are designed to allow for slight misalignment, but if the back of the reamer isn't aligned with the front of the reamer when the pilot enters the throat, then the reamer will have to absorb that by flexing and/or cutting oversized.

By using the reamer for the whole chamber, it follows whatever path the bore takes very smoothly and when the pilot reaches the throat everything is fully supported and aligned.

Well... Why wouldn't the throat be straight?

If you're indicating the throat, and an inch foward, the breech end becomes unknown. You pre-bore to solve the potential issue you're talking about. It's to get the body aligned perfect to what you've dialed in for the throat.

If you're letting the pilot take your reamer for a walk, you'll end up with oversized or oval chambers.

If your reamer would have been in a bind due to your concern, it would also be in a bind without the pre-bore.


I started boring with a "TS-C06K-SCLCR06" tiny carbide bar. I use the polished inserts made for aluminum. They take light/finish cuts in stainless and leave a gorgeous finish.


1663593037384.png
 
I'd much rather have my rifles metalwork done by a guy who understands rifles than a guy who understands 100 different complex machine tools and thinks a thou is good.
This is very true, imo. Also, machining isn't just putting a cutter to metal but about figuring out setups for doing it well. This is a lost skill set in an age of cnc programmers coming out of trade schools and where someone like Jackie truly excells in his trade. His pics show lots of impressive ingenuity.
 
Last edited:

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Forum statistics

Threads
165,669
Messages
2,200,339
Members
79,028
Latest member
Stanwa
Back
Top