Barrel contour advice

[Knee Doc]

Hi. I am about to commission a 7SAUM build, through a well regarded custom rifle builder in UK, who has previously built me a 300WBK, based on a Borden action….

Question is based around barrel contour and I am aiming for 26" 1:8….I am sure others might disagree, but that's my aim.

Rifle build weight is to be between 9-9.75lb, before optics and moderator (all my rifles have moderators and I am a big fan, having already struggled with reduction in hearing quality).

The rifle will be a cross over, for range work and hunting (open ground, hence not needing/wanting a shorter barrel) with 180gr likely bullet weight.
I am struggling with fixing on contour of barrel. It will be a Krieger, as the rifle maker has close ties to that barrel manufacturer and I have no problem with their products. Barrel will be fluted, as I like the look and all other reasons can be refuted TBH.

3 options
Heavy Bull Sporter. .750 muzzle diam (#6 contour on Krieger outline)
Light Palma. .750 muzzle diam (#16 contour on Krieger outline)
Rem Varmint Contour. 0.830 muzzle diam.
All 3 options would weigh about 4.5lb pre-fluting.

My concern is to ensure highest number of shots before group size opens or POA shifts. As the breech and neck dimensions are different for all the 3 options, what influence would that have on slowing the issue of thermal influence on groups, or would the biggest influence be mid and muzzle dimensions, in which case the Rem Varmint Contour would enable a greater shot count, before groups moved/opened…..???

Apologies for the protracted question and many thanks for any wisdom that can be provided…

Knee Doc

 

[Rick Richard]

I don't know how this compares to Krieger, but I really like the Bartlein 3b contour fluted.

 

[sable tireur]

My concern is to ensure highest number of shots before group size opens or POA shifts.

I'm unsure about this idea as with a hunting barrel, very few shots are usually considered. The only variable I ran into was depredation hunting where the number of consecutive shots could be higher.

Now target shooting can be vastly different, of course. Watch a LR Benchrest match or an F-Class competition.

The contour I have used for quite a number of both competition rifles and depredation hunts is the #19 Hunter. Very stiff and has a little more barrel weight and the diameters to allow for decent fluting. I look for longer breech lengths, as I dislike those which come with a 2.5" or 2.75" breech length.

Enjoy the process!

 

[Knee Doc]

I do take your point, as to do hunting barrels require maintaining POI over a short number of shots….
I am involved in a Red Deer culling program, usually. In these situations it is not uncommon to fire 5 shots in rapid succession, and indeed I have had to change magazines (10 round) when culling a larger sized herd, so thermal stability is of concern to me, even when hunting……

 

[sable tireur]

I do take your point, as to do hunting barrels require maintaining POI over a short number of shots….
I am involved in a Red Deer culling program, usually. In these situations it is not uncommon to fire 5 shots in rapid succession, and indeed I have had to change magazines (10 round) when culling a larger sized herd, so thermal stability is of concern to me, even when hunting……

Yes, that's what I was thinking about with regard to hunting. Cull hunting is a completely different preparation and mindset than the typical 1 or 2 shots in a standard hunting situation.

I've been on cull (depredation) hunts in a couple of other countries and several here in the US. My barrels were necessarily more stout and shorter than I would normally build for a hunting rifle. The #19 or Hunter contour is a good design for this style of hunting.

Best.

 

[Recon$$]

I would go as heavy as you can while maintaining your weight expectations. It will pay off on the range.

 

[Pat Byrne]

To Stay under 10#'s with a can I think you might have to go with a smaller contour than you outlined..

I didn't read the OP well enough.. He said up to 9 3/4 BEFORE can and optics.. Carry on..

When I think hunting rifles I imagine a rifle I will be carrying a LOT so generally think in terms of total weight..

 

[APDDSN0864]

I'm unsure about this idea as with a hunting barrel, very few shots are usually considered. The only variable I ran into was depredation hunting where the number of consecutive shots could be higher.

Now target shooting can be vastly different, of course. Watch a LR Benchrest match or an F-Class competition.

The contour I have used for quite a number of both competition rifles and depredation hunts is the #19 Hunter. Very stiff and has a little more barrel weight and the diameters to allow for decent fluting. I look for longer breech lengths, as I dislike those which come with a 2.5" or 2.75" breech length.

View attachment 359680

Enjoy the process!

This is exactly the contour I have used with both of my 6.5x280AI rifles. The straight taper seems to resist POI shift as they heat up better than some others.
While I don't compete, I do shoot long range steel and use both of these rifles for long range predator control. Shots can be infrequent, or as fast as I can run the bolt and get back on target.
I use them in a climate than ranges from below 0F to 110F without changes in first round POI or subsequent shot POI.
Krieger is an excellent barrel maker!

Ed

 

[Jeffrey Van Zandt]

Hi. I am about to commission a 7SAUM build, through a well regarded custom rifle builder in UK, who has previously built me a 300WBK, based on a Borden action….

Question is based around barrel contour and I am aiming for 26" 1:8….I am sure others might disagree, but that's my aim.

Rifle build weight is to be between 9-9.75lb, before optics and moderator (all my rifles have moderators and I am a big fan, having already struggled with reduction in hearing quality).

The rifle will be a cross over, for range work and hunting (open ground, hence not needing/wanting a shorter barrel) with 180gr likely bullet weight.
I am struggling with fixing on contour of barrel. It will be a Krieger, as the rifle maker has close ties to that barrel manufacturer and I have no problem with their products. Barrel will be fluted, as I like the look and all other reasons can be refuted TBH.

3 options
Heavy Bull Sporter. .750 muzzle diam (#6 contour on Krieger outline)
Light Palma. .750 muzzle diam (#16 contour on Krieger outline)
Rem Varmint Contour. 0.830 muzzle diam.
All 3 options would weigh about 4.5lb pre-fluting.

My concern is to ensure highest number of shots before group size opens or POA shifts. As the breech and neck dimensions are different for all the 3 options, what influence would that have on slowing the issue of thermal influence on groups, or would the biggest influence be mid and muzzle dimensions, in which case the Rem Varmint Contour would enable a greater shot count, before groups moved/opened…..???

Apologies for the protracted question and many thanks for any wisdom that can be provided…

Knee Doc

I would go with the proof carbonfiber in the rem cont

 

[codyadams]

I think to accurately answer your question we need to know the weight of your stock/action/bottom metal and if you want that weight to be with or without the supressor/supressor wrap.

I would add the weight of all your other components minus barrel, and then go with the heaviest contour to still make your weight requirements. Keep in mind, listed barrel weights on Kriegers site (and most others) is for the blank, not the finished barrel. Chambering/threading muzzle only takes off a couple oz, however cutting the excess muzzle length and possibly shank can make a significant difference in final weight.

Hunting stocks these days can range from 17 oz or so up to well over 4 lbs or more, and actions can be as light as 16 oz for something like a Pierce skeleTI, up to north of 40 oz for a bench rest type. I saw you mention Borden on your last build, but did not specify what this one shall be. More information can help us help you!

 

[tacomHQ]

"My concern is to ensure highest number of shots before group size opens or POA shifts. "
Our barrels will resist POA shift, group size change, ES and SD drift. It is quite common to shoot our 300Norma for 20shot strings, 6.5 45shot strings... third party noted. When on range with mil groups and we are truing they stop at 6-9 rounds due to the inaccuracy build up. We are still shooting holding better groups 15-20rounds later. Our TRG-42 in 300WM weighs 11pounds with a 26" barrel. Barrel: 1.3action to 1.16" muzzle-- 12-8 Bartlein Gain twist. With newer actions and chassis it would meet the 9.75lb criteria.
We are not competing with 1-3shot pure hunting barrels. Continued high precision over extended round count is our focus. You will also find our load development is very forgiving and the recoil pulse is very much reduced... a recent post notes watching their impacts with a 300WM at 100yds.

 

[Knee Doc]

I think to accurately answer your question we need to know the weight of your stock/action/bottom metal and if you want that weight to be with or without the supressor/supressor wrap.

I would add the weight of all your other components minus barrel, and then go with the heaviest contour to still make your weight requirements. Keep in mind, listed barrel weights on Kriegers site (and most others) is for the blank, not the finished barrel. Chambering/threading muzzle only takes off a couple oz, however cutting the excess muzzle length and possibly shank can make a significant difference in final weight.

Hunting stocks these days can range from 17 oz or so up to well over 4 lbs or more, and actions can be as light as 16 oz for something like a Pierce skeleTI, up to north of 40 oz for a bench rest type. I saw you mention Borden on your last build, but did not specify what this one shall be. More information can help us help you!

Very sorry for not checking in earlier…work has been somewhat distracting..
To provide clarity, current proposed build is as follws
Borden Ridgeline stainless
Hawkins Precision bottom metal and detachable magazine
TriggerTech trigger
Either McMillan Game Stalker or else U-1 stock….probably going the route of the A-1, as I like an adjustable comb and the slight angulation on the grip is more to my liking than some of the other McM tactical stock options.
Will have 20MOA rail fitted.

Suppressor not included in weight and I usually put a PMII on my rifles, but looking at other options for this build.

All the best.

KneeDoc