Questions about barrel contour rules

L

Lucky Shooter

Guest
From IBS Rules: HV contour
a barrel not less than 18 inches long, a diameter at and not more than 5 inches ahead of
the boltface of not more than 1.250 inches and a diameter at any point between the
muzzle and 5 inches in front of the boltface not greater than would be defined by a
straight taper between such point 5 inches in front of the boltface at 1.250
inches diameter and the muzzle at .9 inch diameter at 29 inches.

From NBRSA Rules: HV contour
The barrel would not be less than 18” long forward of the
bolt face and a diameter of not more than 1.250 inches from
the bolt face forward 5 inches. From said 5-inch point, the
diameter would not be greater than would be defined by a
straight taper between such point and a muzzle diameter of
.900 at 29 inches.

Seems both sets of rules refer to a tapered portion from a maximum of 1.250" to a muzzle dimension of .9"------at a 29" point.

The question I have concerns the beginning of the 29" portion---whether this portion starts at the bolt face ?----or----starts from the end of the 1.250" section ?

Anybody know how this rule is interpreted ?

Thanks for any information on this.

A. Weldy
 
The way that I read it is from the 1.250 where it starts its straight taper dimension, not from the boltface. Do you have a specific example that you are in question about?
Butch
 
The 29" is from the boltface.

Maximum barrel dimensions would be a 29" barrel that has 5" of 1.250 parallel taper (straight shank) and then would taper to .9 @ 29" from the boltface. Such a barrel would be too heavy so you may then cut it back to as short as 18" from the boltface.

al
 
Thanks Butch

Specifically,what I have is a Krieger 220 Beggs barrel with HV contour. At the time this gun was built, no consideration was given to the rules of organized BR competition.

I now want to move toward competition and wonder if the barrel maker's contour can be used as is----or----is this taper contour parameter subject to be checked at matches.

Just wanted to address this concern.

Thanks.

A. Weldy
 
If you take a piece of paper and draw the barrel dimension shown in the rule book and lay your barrel on it. If it fits, it is legal. It can be .900 at the muzzle and reverse tapered to ,say, .500 in front of the tenon and still be legal. It can be any shape as long as it fits within the dimensions.
Butch
 
Al,
I believe that the measurement is stated from a point that is 5" in front of the boltface if it is 1.250 and then 29" to a .900.
Butch
 
Weldy

If it was purchased a true Krieger HV contour, it will be legal. All of the major Custom Barrel Manufacturers that make barrels specifically for Benchrest specifically make the contours to fit within the rules set forth by the NBRSA and IBS.........jackie
 
Thanks to all

I bought the barrel from Bruno and the breech end was stamped as a Krieger with all the specs.

A. Weldy
 
Butch,

If this were true then the .9 measurement would/could occur at a point 34" from the bf.

al
 
That is true Al. You could actually use a 40" blank as long as it ain't longer than 29" from the point that the 1.250 starts tapering to the .900. The straight part has nothing to do with the taper. It just can't be over 5" straight from the boltface.
Butch
 
Sorry Butch

The .900 dim. is 29" from the bolt face. 5'' straight and 24" taper. Page 68 NBRSA rule book #36.

By the way the new rule book #37 is at the printer. HOORAY

Don
 
This is from the NBRSA Site

Don Nielson said:
The .900 dim. is 29" from the bolt face. 5'' straight and 24" taper. Page 68 NBRSA rule book #36.

By the way the new rule book #37 is at the printer. HOORAY

Don
Click to expand...

The barrel would not be less than 18” long forward of the
bolt face and a diameter of not more than 1.250 inches from
the bolt face forward 5 inches. From said 5-inch point, the
diameter would not be greater than would be defined by a
straight taper between such point and a muzzle diameter of
.900 at 29 inches.


The way I read this, Butch is correct..............GW
 
Read it again Gary, it's actually very clear IMO. :)

Just the underlined part says it all.


"from the point" ........... this is the point 5" from the bf

"to the point (muzzle)" ................ this is the point 29" from the bf


al
 
well...lets get back to real world. someone do the math.

use both versions since its still up in the air.

what is my muzzle dia at 21" and at 24" ( who cares at 29 or 34 ?)

thanks
mike in co
 
alinwa said:
Read it again Gary, it's actually very clear IMO. :)

Just the underlined part says it all.


"from the point" ........... this is the point 5" from the bf

"to the point (muzzle)" ................ this is the point 29" from the bf


al
Click to expand...
and the rule clear states from the 5" dia when disscussing the 29"taper....


but al..you added "from the bf"...the rule does not say that in the 29" line...it may imply but since it is not in print....we have this disscussion.



mike in co
 
mike in co said:
well...lets get back to real world. someone do the math.

use both versions since its still up in the air.

what is my muzzle dia at 21" and at 24" ( who cares at 29 or 34 ?)

thanks
mike in co
Click to expand...

For a HV barrel --Max. 1.016"@ 21" long from bolt face and .972" @24" from bolt face. It's all in black and white at the IBS website. Go to downloads and click on rules. Scroll down to the last page(29). It's all drawn out with pics.---Mike
 
Last edited:
Jackie answered at least part of the original poster's question -- you can trust the barrel maker's taper. Another part is, I've never seen anybody check barrel taper at a match. The only reason would be if some other competitor protested the barrel, & that's pretty unlikely, too.

But just for fun, the rule doesn't specifically day what the taper must be after the 29" point (where ever it is). Sounds like a reverse taper after that would be something you could contend was legal -- Except you wouldn't make weight without using unobtainium.
 
Don wins. If you look on the NBRSA website, and click on the rule book, and download the 37th revision, and then scroll down to page 113, you will see a drawing, with notes, that explains the whole thing. The .900 is at the end of a tapered portion that starts at 1.250, and is 24 inches long. You fellers that were calling it the other way must not have gotten that far in your rule book. The drawing has been in every one that I have ever seen. Badaboom!:D
 
I would go this far

With the Heavy Varmint and Light Varmint contours offerred by Shillen, Krieger, Hart, and Bartlein, I would venture a guess that it is impossible to render the contour illegal, unless you cut it shorter than 18 inches,........jackie
 
Appears I asked a useless question

The drawing was the key.

A .35" change over 24" would show a taper of just under .015" in 1".

The same change over 29" would show a taper of about .012" in 1".

I measured the barrel at a few places in 1" increments and got about .014" to .016" change from each mark to the next----appears to back up Jakie's confidence in the barrel maker.

I apologize for the stupid question. Thanks for the replies.

A. Weldy
 
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