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Posted: 2/15/2006 3:19:18 PM EDT
What does it accomplish? What bullet weight do the RR varminters seem to like 1/8 bull?
Link Posted: 2/15/2006 3:54:21 PM EDT
[Last Edit: 2/15/2006 3:55:12 PM EDT by Mike_Mills]
Air gaging is a non-destructive measurement technique capable of measuring the very small variations in bore diameter along the length of a barrel's bore.

Supposedly, a good barrel will have small variations along its length and if there is a variation, it is prefered that the bore get tighter as you approach the muzzle, rather than the other way around. For example, if you find a barrel which is wider in its middle and tighter at each end, this is supposedly a less good barrel.

The armories (i.e., Springfield Armory) used to air gage some of the barrels. The gaged barrels were marked (stamped) with a small star at their muzzle ends. These came to be known as "star gaged" barrels. The star was actually meaningless with respect to the barrel's quality as it signified only that the inspection had been done, not that the barrel was a particularly good one. The results of the gaging were attached to the barrel and an armorer could select the good ones for use on the NM rifles.

My RRA varminter has a 1/8" twist. It shoots everything I put in it very well. I have used Sierra MatchKings from 52 to 80 gr and the Hornady 75 gr HPBT-M bullet. Your 1/9" twist should shoot the 75's well but probably NOT the 80 S-MK.
Link Posted: 2/15/2006 4:08:16 PM EDT
A star gage is an entirelly different measuring system, it's not the same as an air gauge.
Link Posted: 2/15/2006 5:38:32 PM EDT
[Last Edit: 2/15/2006 5:46:21 PM EDT by Gunzilla]
The barrel is pressurized, then they run a device that is sort of like a plug through the barrel, this plug is a known size and slightly smaller than the bore so that some of the air leaks around it, inareas where the bore is tight, the air pressure increases, in areas where it is loose, the prssure drops.

By monitoring the pressure, a very precise measurement can be made of what the relation of the bore size is to the known gauge/plug... that make sense at all?

Heck... while we're at it. A barrels grade is up to the maker really, but the blanks tend to be offered in about three grades -- a common way of doing it is simply from the start, when the blank is gun drilled, the exit hole will not be in the center of the blank, how far it is off is one common method of grading the blank.

Just say for example Acme barrels drills a bunch of blanks, they may measure the exit hole in relation to the center of the blank and sort them out like this:

If the hole is less than the caliber of the bore off center, it is a Premium barrel

If the hole is more than one caliber, but say less than 1.5 or 2, it is a Regular barrel

If it is worse than a Regular barrel, it is sold to another barrel company for them to mark with their name!
Link Posted: 2/15/2006 6:31:44 PM EDT

Originally Posted By Gunzilla:
The barrel is pressurized, then they run a device that is sort of like a plug through the barrel, this plug is a known size and slightly smaller than the bore so that some of the air leaks around it, inareas where the bore is tight, the air pressure increases, in areas where it is loose, the prssure drops.

By monitoring the pressure, a very precise measurement can be made of what the relation of the bore size is to the known gauge/plug... that make sense at all?

Heck... while we're at it. A barrels grade is up to the maker really, but the blanks tend to be offered in about three grades -- a common way of doing it is simply from the start, when the blank is gun drilled, the exit hole will not be in the center of the blank, how far it is off is one common method of grading the blank.

Just say for example Acme barrels drills a bunch of blanks, they may measure the exit hole in relation to the center of the blank and sort them out like this:

If the hole is less than the caliber of the bore off center, it is a Premium barrel

If the hole is more than one caliber, but say less than 1.5 or 2, it is a Regular barrel

If it is worse than a Regular barrel, it is sold to another barrel company for them to mark with their name!



So, does that mean my RR bull barrel is a cull and not as accurate?
Link Posted: 2/15/2006 7:04:30 PM EDT

Originally Posted By arteacher:

Originally Posted By Gunzilla:
The barrel is pressurized, then they run a device that is sort of like a plug through the barrel, this plug is a known size and slightly smaller than the bore so that some of the air leaks around it, inareas where the bore is tight, the air pressure increases, in areas where it is loose, the prssure drops.

By monitoring the pressure, a very precise measurement can be made of what the relation of the bore size is to the known gauge/plug... that make sense at all?

Heck... while we're at it. A barrels grade is up to the maker really, but the blanks tend to be offered in about three grades -- a common way of doing it is simply from the start, when the blank is gun drilled, the exit hole will not be in the center of the blank, how far it is off is one common method of grading the blank.

Just say for example Acme barrels drills a bunch of blanks, they may measure the exit hole in relation to the center of the blank and sort them out like this:

If the hole is less than the caliber of the bore off center, it is a Premium barrel

If the hole is more than one caliber, but say less than 1.5 or 2, it is a Regular barrel

If it is worse than a Regular barrel, it is sold to another barrel company for them to mark with their name!



So, does that mean my RR bull barrel is a cull and not as accurate?



No... sorry, that was sort of a joke for a few on here...

RRA uses Wilson barrrels for the stainless guns and they are good quality... Dollar for dollar, they are a great barrel really.
Link Posted: 2/15/2006 9:49:14 PM EDT
[Last Edit: 2/15/2006 9:49:40 PM EDT by Mike_Mills]

Originally Posted By stiles:
A star gage is an entirelly different measuring system, it's not the same as an air gauge.




If I mis-remembered about star gaging and how it differs from air gaging, please refresh my memory.
Link Posted: 2/15/2006 10:06:38 PM EDT
"The armories (i.e., Springfield Armory) used to air gage some of the barrels. The gaged barrels were marked (stamped) with a small star at their muzzle ends. These came to be known as "star gaged" barrels. The star was actually meaningless with respect to the barrel's quality as it signified only that the inspection had been done, not that the barrel was a particularly good one. The results of the gaging were attached to the barrel and an armorer could select the good ones for use on the NM rifles."

That was my first thought. My Issued rack-grade M14 [with SAGE stock and national match op rod guide] shot significantly better than my personal supermatch M1A. (I wouldn't buy a springfield M1A again.)

The barrel contour of the springfield is like two to four lbs heavier too.
Link Posted: 2/15/2006 11:31:08 PM EDT

Originally Posted By Mike_Mills:
If I mis-remembered about star gaging and how it differs from air gaging, please refresh my memory.



No problem this is a star gage. source Sorry that I was brief before I had to take off.
Link Posted: 2/16/2006 2:50:04 AM EDT
Tagged. A question I always had, an answer I though I always knew but never asked.

Love to learn new details.
Link Posted: 2/16/2006 5:55:07 AM EDT
.
Link Posted: 2/16/2006 7:48:23 AM EDT


Just say for example Acme barrels drills a bunch of blanks. . . .



So where can I get me one of them Acme barrels!?!?!?!?
Gotta thave the latest, most obscure doo dad, ya know. he
Amen on the Wilson stainless bbl. I've got one on my RRA middy and with Black Hills remanuf match it's one-hole groups at 100 yds all day as long as I do my part.
Link Posted: 2/16/2006 12:21:13 PM EDT
The typical air gauge has an an air column which as Gunzilla pointed out it's job is to measure pressure . They are simple as can be, take pressurized air, filter it, run it though a regulator and then the air runs up a graduated scale which has a float in it and then the air is routed to the tooling. For a bore your tooling would be a spindle and it's a plug that has two opposing holes where the air escapes from. The spindle is a bit undersized of the bore your measuring and it floats inside the bore similar in concept to an air bearing. Now if your bore gets bigger the pressure drops and the float on the column goes up, if the bore gets tighter the pressure increases and the float sags. Well that's pretty much it in a nut shell.

Sheffield Air Gauges

Link Posted: 2/16/2006 3:11:09 PM EDT
[Last Edit: 2/16/2006 3:12:37 PM EDT by Gunzilla]

Originally Posted By fogofwar:


Just say for example Acme barrels drills a bunch of blanks. . . .



So where can I get me one of them Acme barrels!?!?!?!?
Gotta thave the latest, most obscure doo dad, ya know.

I got to tour the Shilen plant a few years ago when they were rebarreling my Rem 700. I thought air-guaging was some special, tedious process but it is really quite simple. It separates the good from the not-so rather quickly.

Amen on the Wilson stainless bbl. I've got one on my RRA middy and with Black Hills remanuf match it's one-hole groups at 100 yds all day as long as I do my part.



Acme only makes two barrels for ARs and they are not very popular on here... they make the "Poser" and the "Wannabe"

Not sure why they don't sell more, but rumore is they are stading by to name a barrel after the next country we send troops into
Link Posted: 2/17/2006 7:36:07 PM EDT
Link Posted: 2/17/2006 9:12:15 PM EDT

Originally Posted By AR15barrels:
The key thing to learn from this post and I am not sure it was stressed very well is that just because a barrel had been "Air Gauged", that does NOT autumatically make it a better barrel.
That just means that it has been MEASURED.



This is very true, it's just a technique to measure 1 dimension of a bore over it's length. Advertising "air-gauged" is like advertising "ISO 900[1,2]" as a measurement of quality, sure you have to have a quality system documented and it's audited to see if your employees understand the system and follow it but the QUALITY SYSTEM IS NEVER AUDITED TO SEE IF IT IS EFFECTIVE BY THE AUDITORS. That has never stopped a marketing type from advertising "ISO 9001 quality system" but that's how things go in the advertising world.
Link Posted: 2/17/2006 10:33:12 PM EDT

Originally Posted By AR15barrels:
Companies like Shilen, Douglas, Krieger, Pac-Nor etc... have higher standards on what they let out the door and that's what you are really paying for when you buy a high-end barrel.




Do the E.R. Shaw barrels fit in the "higher standard" group too. ?
Link Posted: 2/17/2006 10:50:41 PM EDT
Link Posted: 2/17/2006 11:03:57 PM EDT

Originally Posted By AR15barrels:
For instance, Krieger and Rock Creek both offer button rifles and single point cut rifled barrels.



Krieger makes button rifled barrels? I've never heard that before.
Link Posted: 2/17/2006 11:17:51 PM EDT
Link Posted: 2/17/2006 11:36:47 PM EDT
thanks for the 411!
Link Posted: 2/17/2006 11:55:31 PM EDT
Acme Barrels...

In use by WESCOG graduates everywhere.





Sorry - I couldn't resist.
Link Posted: 2/18/2006 7:18:33 AM EDT
Randall...

I noitce that you left a few names that I like/use off of your list of premium barrel makers... Schneider and BJO for example.

Do you consider these and some of the even more obscure names sort of "out of reach" in a way? Too difficult to locate or too long of a waiting list to consider primium commercial barrels, perhaps more custom made barrels?
Link Posted: 2/18/2006 8:17:33 AM EDT
Link Posted: 2/18/2006 8:30:12 AM EDT

Originally Posted By AR15barrels:

Originally Posted By Gunzilla:
I noitce that you left a few names that I like/use off of your list of premium barrel makers... Schneider and BJO for example.

Do you consider these and some of the even more obscure names sort of "out of reach" in a way? Too difficult to locate or too long of a waiting list to consider primium commercial barrels, perhaps more custom made barrels?



Yes, I would group those with all the smaller custom makers like boots obermeyer, van horn, broughton etc...
BJO = Boots Obermeyer?
Great barrels, but many people have not heard of them and they are not widely known or as easily obtained.



we are thinking the same here it seems... oh, yes BJO is Boots

this year I am starting to sell limited precision/sniper rifles to individuals, even with the small numbers I am doing, it is hard to get enough of the top name barrels in...
Link Posted: 2/18/2006 9:08:38 AM EDT
Randall,

Would it be possible for you to supply some detailed information on how blanks are manufactured? I read your section on how you make barrels and it was very informative; thank you for taking the time to write it.
Link Posted: 2/18/2006 9:18:34 AM EDT

Originally Posted By Gunzilla:

Originally Posted By AR15barrels:

Originally Posted By Gunzilla:
I noitce that you left a few names that I like/use off of your list of premium barrel makers... Schneider and BJO for example.

Do you consider these and some of the even more obscure names sort of "out of reach" in a way? Too difficult to locate or too long of a waiting list to consider primium commercial barrels, perhaps more custom made barrels?



Yes, I would group those with all the smaller custom makers like boots obermeyer, van horn, broughton etc...
BJO = Boots Obermeyer?
Great barrels, but many people have not heard of them and they are not widely known or as easily obtained.



we are thinking the same here it seems... oh, yes BJO is Boots

this year I am starting to sell limited precision/sniper rifles to individuals, even with the small numbers I am doing, it is hard to get enough of the top name barrels in...



One of the little guys that I used on an AR and soon a Savage was Badger cut by Northern Competition. A little spendy but simply fantastic.

Link Posted: 2/18/2006 1:30:24 PM EDT
lol! I'm betting the next Acme barrel will be named the Iranian and will have to fire nukes!

I'm sensing a need for a barrel oracle......
Link Posted: 2/18/2006 1:39:27 PM EDT
Link Posted: 2/18/2006 2:37:10 PM EDT
[Last Edit: 2/18/2006 2:38:50 PM EDT by olds442tyguy]
Randall, what do you think of polygonal rifling? It seems people either hate it or live by it with no inbetween.

Also, how do you feel about barrel dimpling as opposed to traditional fluting? Does it offer any significant advantages and/or disadvantages?

ETA: Excellent topic. It's nice to have a thread that has information contributed by people that actually know what they're talking about.

Link Posted: 2/18/2006 3:55:00 PM EDT

Originally Posted By olds442tyguy:
Randall, what do you think of polygonal rifling? It seems people either hate it or live by it with no inbetween.

Also, how do you feel about barrel dimpling as opposed to traditional fluting? Does it offer any significant advantages and/or disadvantages?

ETA: Excellent topic. It's nice to have a thread that has information contributed by people that actually know what they're talking about.




Crap! I was going to get in on this too

Looks good Randall... one thing for folks to think about as far as barrel quality is the rifling itself; some barrel makers take great care to make sure that 1:7 twist really is 1:7 and consistant all the way through -- it is not uncommon for "lesser" barrels to be almost a full inch off of what they claim to be... or better yet, to have what I like to call GLGGLLGLGGT rifling:

Gain Lose Gain Gain Lose Lose Gain Lose Gain Gain Twist
Link Posted: 2/18/2006 4:05:03 PM EDT
[Last Edit: 2/18/2006 4:06:04 PM EDT by olds442tyguy]

Originally Posted By Gunzilla:

Originally Posted By olds442tyguy:
Randall, what do you think of polygonal rifling? It seems people either hate it or live by it with no inbetween.

Also, how do you feel about barrel dimpling as opposed to traditional fluting? Does it offer any significant advantages and/or disadvantages?

ETA: Excellent topic. It's nice to have a thread that has information contributed by people that actually know what they're talking about.




Crap! I was going to get in on this too

Looks good Randall... one thing for folks to think about as far as barrel quality is the rifling itself; some barrel makers take great care to make sure that 1:7 twist really is 1:7 and consistant all the way through -- it is not uncommon for "lesser" barrels to be almost a full inch off of what they claim to be... or better yet, to have what I like to call GLGGLLGLGGT rifling:

Gain Lose Gain Gain Lose Lose Gain Lose Gain Gain Twist


I always welcome your opinions.

As for the GLGGLLGLGGT rifling, didn't you know that's a new modular barrel design? How else are we supposed to get all of the benefits from both 1/7 and 1/9 twists in one barrel.
Link Posted: 2/18/2006 5:45:40 PM EDT
Link Posted: 2/18/2006 5:50:16 PM EDT
Link Posted: 2/18/2006 9:28:26 PM EDT
[Last Edit: 2/18/2006 9:30:47 PM EDT by Gunzilla]

Originally Posted By AR15barrels:

Originally Posted By Gunzilla:

Looks good Randall... one thing for folks to think about as far as barrel quality is the rifling itself; some barrel makers take great care to make sure that 1:7 twist really is 1:7 and consistant all the way through -- it is not uncommon for "lesser" barrels to be almost a full inch off of what they claim to be... or better yet, to have what I like to call GLGGLLGLGGT rifling:

Gain Lose Gain Gain Lose Lose Gain Lose Gain Gain Twist



Ywp, I have asked a bunch of makers about their twist rate tolerance.
The good ones will tell you flat out, while the others get suddenly vague with their answers.
The most common spec quoted is +/- 1/2".
The actual rate of twist is not NEARLY as important as the consistency of the twist rate.
As Gunzilla already said, some blanks will vary through the length of the barrel.
If anything you want either a gain twist, slower at the breech to faster at the muzzle or at least a consistent twist from breech to muzzle.



I know some of the old timers... hey, hold one... those possesed with sage like wisdom (just had a birthday) say the best thing about gain twist barrels is you know what end the bullets should come out of
Link Posted: 2/18/2006 9:55:33 PM EDT
[Last Edit: 2/18/2006 9:58:28 PM EDT by AR15barrels]
Link Posted: 2/18/2006 11:58:32 PM EDT
That border barrels article is pretty good. Benchrest.com has a thread with a couple of cut rifle barrel makers showing their equipment and talking shop. One of the guys is Jermey O'Neal of border barrels and he post pictures of both their sine bar machines and hydraulic monster. mhb provides some great insight into the process of cut rifling, especially his commentary on the cutter box (there be black magic here, har!!!). Of course there is one pseudo expert 'tard that tells everybody how much it would cost to make a modern cut rifling machine and how fast Pratt & Whitney machines wear out (he actually argues the wear issue with someone that owns a P&W sine bar machine, some people). Ok I'm back to being the 'tard pseudo expert of this thread .
Link Posted: 2/19/2006 2:56:12 AM EDT

Originally Posted By AR15barrels:
Here is a more detailed article on barrel making that I ran into tonight...

www.border-barrels.com/articles/bmart2.htm




Originally Posted By stiles:
That border barrels article is pretty good. Benchrest.com has a thread with a couple of cut rifle barrel makers showing their equipment and talking shop. One of the guys is Jermey O'Neal of border barrels and he post pictures of both their sine bar machines and hydraulic monster. mhb provides some great insight into the process of cut rifling, especially his commentary on the cutter box (there be black magic here, har!!!). Of course there is one pseudo expert 'tard that tells everybody how much it would cost to make a modern cut rifling machine and how fast Pratt & Whitney machines wear out (he actually argues the wear issue with someone that owns a P&W sine bar machine, some people). Ok I'm back to being the 'tard pseudo expert of this thread .



Fascinating stuff!
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