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Barrel contour?
- Thread starter harps
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jpndave
Well-Known Member
I've been wanting to start a discussion about barrel contour for two builds I am working on. More on an optimized design direction rather than which of the available contours to use. LMK if that diverges too much from your intents here and I can certainly start one up instead.
This is a good listen, I had already listened to it when it came out but good to review again. Frank Green is a knowledgeable guy. At about 4:10 they talk a little about one of the GAP contours that changes the shank length to match the chamber. Which leads to...
The direction I have been pursuing - as @HuntnPack mentioned - shorten shorten the shank to just longer than the shoulder of the cartridge. Then size the taper diameter ahead of the shank to the muzzle to optimize the weight you are after with a heavier taper maybe 0.012"/in or more if you like to the desired muzzle diameter to land the weight at your optimized target. There are calculators out there that get pretty close to actual but playing with the dimensions. I think the stiffness to weight can be changed a bit to make the most use of the weight that is there. Hopefully that makes sense.
Too much?
Dave
This is a good listen, I had already listened to it when it came out but good to review again. Frank Green is a knowledgeable guy. At about 4:10 they talk a little about one of the GAP contours that changes the shank length to match the chamber. Which leads to...
The direction I have been pursuing - as @HuntnPack mentioned - shorten shorten the shank to just longer than the shoulder of the cartridge. Then size the taper diameter ahead of the shank to the muzzle to optimize the weight you are after with a heavier taper maybe 0.012"/in or more if you like to the desired muzzle diameter to land the weight at your optimized target. There are calculators out there that get pretty close to actual but playing with the dimensions. I think the stiffness to weight can be changed a bit to make the most use of the weight that is there. Hopefully that makes sense.
Too much?
Dave
harps
Well-Known Member
Vary nice!
harps
Well-Known Member
Checking it out
Thanks
harps
Well-Known Member
Not at all , any and all info is great!
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The Mountain Hunter contour with deep spiral Flutes on my Seekins Element is a good example of this approach.
Works Great for a lightweight build.
They have a couple different approaches to
Contour & Fluting. Good stuff.
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I went with a carbon barrel because I wanted a "heavy" contour with a long barrel, but needed it to be lightweight. I very well could have went with a much lighter contour steel barrel and ended up with the same weight, but the stiffness wouldn't be there. I now hunt with a suppressor, so having the extra stiffness the carbon wrap provides is the icing on the cake. Mine is a 28" proof sendero, it weighs less than my 18" varmint contour .308 barrel and shoots better than all the other barrels I've purchased previously.
jpndave
Well-Known Member
Lighter weight and the bling are the usual reasons - at least legitimate reasons. All sorts of claims are made but all the tests I've seen show similar stiffness for the same weight not size. Another advantage is a lighter barrel with a larger muzzle to seat a suppressor. All that said, now that Bartlein has them I would try one if I can make it work on an application. Their bore would be exceptional. It could be had with any twist to meet requirements perfectly, 5R,gain twist would all be possible. There could also be some resonance advantages and other gains. It will be interesting to see where it all goes.
jpndave
Well-Known Member
There is a spreadsheet here that will get you really close on weight and should be extremely accurate as far as comparing the weight differences between contours.
riflebarrels.com
Barrel Weight Calculations For Contoured Barrels - Lilja
With: Excel File by Jean-Pierre PELLEGRYIn another article on our website we have the formulas and reasoning behind the calculations for determining the weights of straight taper and straight cylinder type barrels. In this article we have the formulas to be used in calculating the weights for...
jpndave
Well-Known Member
So my two builds in planning are ish similar. To what you are planning. Not sure if you have the other details sorted out. I want Stainless, cut rifling, 5R, gain twist that kind of narrows things down. I'll be using Bartlein or Rock Creek for these.
1 - Kimber 84M in 6.5CM they come with a really light profile 22". Shank is 1.050" might be able to get away with 1.060" I want to run a 24" and if I optimize the shank length to just past the case shoulder then adjust the barrel taper to the weight and muzzle diameter should get pretty close. 7 (possibly 7.5) Twist Rock Creek on this one as far as I know Bartlein won't go this light with SS. All rock creek cut rifle barrels have a slight gain twist with their setup.
2 - Montana Rifle Co Action in 300 PRC. 26" length. Similar approach but should be more likely to be "off the shelf" or at least close to profile. I've looked at the Bartlein Carbon but not sure the stock can take that larger diameter. Lots to consider. I'll brake this one for sure and looking at the Terminator T1+ or T2. Carbon barrel would allow a bigger brake to look better.
I have a couple of these run on the spreadsheet I'll share when I get to the files from my computer.
FWIW if you look at Bartlein's Sporter contours the #4 though quite heave has a fairly fast/steeper 0.0125"/in taper rather than the 0.010"/in on most of the others. Take that contour and drop the muzzle diameter and keep the taper. It's interesting to see what all the changes do to weight.
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blacktails
Well-Known Member
- Joined
- Dec 24, 2007
- Messages
- 67
For my 7-08 lightweight build, I was aiming for appx. 7lbs and came in just under at 6lb-13oz scoped. Shoots great and is very quick handling.
20" Rock Creek SS #2 sporter with a 1" shank
Stiller Predator SA with fluted bolt
McMillan Edge in Rem. Mtn. Rifle pattern
PT&G Alum. BDL bottom metal with Wyatt's ext. mag box
Jewell Trigger @ 2.5
Bushnell Elite 4200, 2.5-10x40
Talley LWs
20" Rock Creek SS #2 sporter with a 1" shank
Stiller Predator SA with fluted bolt
McMillan Edge in Rem. Mtn. Rifle pattern
PT&G Alum. BDL bottom metal with Wyatt's ext. mag box
Jewell Trigger @ 2.5
Bushnell Elite 4200, 2.5-10x40
Talley LWs
David Malcom
Well-Known Member
I will only use Hawk Hill barrels unless they change the way they operate. Fantastic accuracy, and great people to deal with. I am more than willing to give up a little weight to get what I have gotten from them.
harps
Well-Known Member
This will be helpfulThere is a spreadsheet here that will get you really close on weight and should be extremely accurate as far as comparing the weight differences between contours.
Barrel Weight Calculations For Contoured Barrels - Lilja
With: Excel File by Jean-Pierre PELLEGRYIn another article on our website we have the formulas and reasoning behind the calculations for determining the weights of straight taper and straight cylinder type barrels. In this article we have the formulas to be used in calculating the weights for...
Thanks
harps
Well-Known Member
Accuracy is number one
