What barrel contour for 300 wsm, 1000 yd BR game?

[Mulligan]

Just pondering barrel contour for the next barrel on my f-class rifle.

I know many f-class folks are using 32” straight 1.25” barrels on their long range f-class rigs. Just wondering what the 1000 yard benchrest crowd is using on the bigger calibers?

Was talking to @BoydAllen last evening and he reminded me, many of the 1000 yard BR guys shoot a 300 WSM for those blustery days.

Thanks
CW

 

[dkhunt14]

Most are not using straight 1.250 barrels in BR. They are using tapered barrels because of making weight. Usually 1.250 for about 5 or 6 inches tapering to around .850 to .940. Weight is the issue to decide what barrel. The rule is 17 pounds. Matt

 

[Mulligan]

Most are not using straight 1.250 barrels in BR. They are using tapered barrels because of making weight. Usually 1.250 for about 5 or 6 inches tapering to around .850 to .940. Weight is the issue to decide what barrel. The rule is 17 pounds. Matt

Thanks Matt,
I ask because I was not getting the precision I expected from my 32” straight 1.25 and had the Smith take 2” off in an attempt to help with balance. I really should say, bag riding ability. The 30” barrel is working much better for me and my equipment. Just pondering how taper plays into it. I believe the precision required for your sport is greater than most other sports and am deferring to the experts.
CW

 

[Bart B.]

I don't think there is significant precision difference across all the best competition rifles 30 caliber or less for 1000 yard events. All test groups under 5 to 6 inches is as good as it gets. Of course, a few groups will be close to an inch or two as well as five and six. Free recoiling bench guns shoot 1/3 to 1/4 the group size in matches as those slung up to ones shoulder in prone with both testing 5.5 inches 3600 feet down range.

The more metal tapered off a 1.25" blank X inches long, the less stiff it is. With the load tuned to the barrel's whip frequency, accuracy will be as good as the bullets allow.

I would start at 32 inches, then 2/3rds down barrel life, set it back 2 or 3 inches.

 

[Tim JN]

Thanks Matt,
I ask because I was not getting the precision I expected from my 32” straight 1.25 and had the Smith take 2” off in an attempt to help with balance. I really should say, bag riding ability. The 30” barrel is working much better for me and my equipment. Just pondering how taper plays into it. I believe the precision required for your sport is greater than most other sports and am deferring to the experts.
CW

Balance of the rifle is number one. Even in F-Class with the higher weight limit a slightly tapered barrel will torque less when shot then a round straight barrel making it easier to shoot well. Also the tapered barrel gives you varying harmonics with the different ODs on the taper but this is just a minute issue unless you are at a critical harmonic.

Matt is correct in the taper most used for 17Lb 1000yd benchrest.

Shoot Straight
Tim North
Broughton 5C® Rifle Barrels
920-922-4882

 

[LA50SHOOTER]

Broughton Barrels did a couple of 30" barrels for me that are 1.25" for 6" then straight taper to .930 at the muzzle.
Both chambered in 300 WSM - The first one I've tried had no trouble shooting a 0.081 five shot group @100 yds. right after break-in.
- The "Heavy Varmint" contour will shoot with a good load & decent manners at the bench.

 

[4xforfun]

All of my 30 Cal BR tubes are 30" HV taper.....1.25 for 5 - 6 inches and then strait taper down to .9. Some are fluted, some are not. They are screwed onto a BAT 1.55 round fitted into a Shehane MBR Tracker stock . The guns does have a 1" recoil pad, and I shot it with a Leupold 8.5 -35 LRT for a couple of years. I switched to a NF and in order to make weight with that setup I needed to mill a little bit out of the BBL channel as it is a solid fill. I think that the ST1000's are about a 1/2 pound lighter than the MBR and should work with the NF with no mods.

Tod

 

[Bart B.]

Even in F-Class with the higher weight limit a slightly tapered barrel will torque less when shot then a round straight barrel making it easier to shoot well. Also the tapered barrel gives you varying harmonics with the different ODs on the taper but this is just a minute issue unless you are at a critical harmonic.

As a straight barrel is heavier and stiffer than after it's tapered, why would it torque less when tapered? Please explain the physics that lets this happen.

Which one of those several harmonics is critical? Third? Fifth? A barrel whose resonant frequency is 90 Hz will have eight or more harmonics up to several thousand cycles per second. Both straight and tapered barrels have one resonant and several harmonic frequencies they wiggle at.

Why is it critical? I'm not familiar with something being a critical harmonic.

 

[mr45man]

In theory, the heavier barrel would torque less.

 

[TRA]

Tapered is mo better.

With a tapered bar the forces are triangulated.

 

[Capt. Oblivious]

Balance of the rifle is number one. Even in F-Class with the higher weight limit a slightly tapered barrel will torque less when shot then a round straight barrel making it easier to shoot well. Also the tapered barrel gives you varying harmonics with the different ODs on the taper but this is just a minute issue unless you are at a critical harmonic.

Matt is correct in the taper most used for 17Lb 1000yd benchrest.

Shoot Straight
Tim North
Broughton 5C® Rifle Barrels
920-922-4882

Very interesting