Rebarrel to 6X47 Lapua
- Thread starter b72471
- Start date
Berger recommends the 1in7 so that is the safe bet however I'm sure the 1in7.5 would work more than 95% of the time. The advantage of going to the slower twist is it takes less energy to turn the bullet which means faster velocity.
Me personally I would go with the 1in7 and guarantee the bullet will stabilize. Then again I wouldn't get rid of my 6.5/284 to begin with. What’s wrong with the 6.5/284?
Nothing "wrong" with the 6.5-284, but barrel life will be enhanced considerably by going to the 6x47L Eagleye.
I went from a 1:8 to a 1:7. in my 6-6.5X47L I intuitively believed the 1:7 would be better for the 115's, but I am getting far better velocity that expected, and I believe I have over-done the twist.
Robert Whitley has done extensive experimentation with the 115 Bergers and with something like a 6-Dasher, a 1:7 would be a good choice. for the 3100 fps range, I think a 7.5" twist would be better.
Robert Whitley has done extensive experimentation with the 115 Bergers and with something like a 6-Dasher, a 1:7 would be a good choice. for the 3100 fps range, I think a 7.5" twist would be better.
The 6.5-284 is a fine caliber, nothing wrong with the one I have, I'm just striving for improvment in equipment and would like to try the 6X47L with 115gr Bergers.
Ian, do you have a barrel in a 7.5 twist in a light varmet contour?
Bill
Ian, do you have a barrel in a 7.5 twist in a light varmet contour?
Bill
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I would hardly call the 6X47 an improvement over the 6.5/284.
Just a quick compare.
1000yards 10mph wind, sight in @ 100yards
6X47 w/ Berger 115VLD BC=.551 loaded to 2950fps
Gives 268" drop and 65" wind drift.
the 6.5/284 w/ Berger 140VLD BC=.618 loaded to 3000fps
Gives 20" less drop and 10" less wind drift.
If you miss read the wind that could be a big help.
As far as barrel life and recoil the 6X47 may be better but why not just use a lighter load in the 6.5/284 if your worried about those things.
the 6.5/284 w/ Berger 140VLD BC=.618 loaded to 2875fps
Gives the same drop as the 6X47 and still has 7" less wind drift. At < 2900fps barrel life on the 6.5, barrel life should improve drastically.
Not trying to troll, just looking for the error of my way of thinking. Seems like the 6.5/284 is getting a bad rep and don't understand why.
Dave
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I have to admit, I have no experience with benchrest. All my shooting is done from a bipod unless I'm testing loads.
Guess I've never considered recoil an issue when it comes to accuracy. So why exactly does recoil effect the accuracy when it comes to bench rest? I have a few ideas but I'm probably wrong.
Dave
Guess I've never considered recoil an issue when it comes to accuracy. So why exactly does recoil effect the accuracy when it comes to bench rest? I have a few ideas but I'm probably wrong.
Dave
Mystic Precision
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I would recommend the 1 in 7 twist because ALL barrel makers have some error in their rifling production. If 7.5 twist is right on the line, it would really suck if you got a 7.75 or 7.93 twist and run into stability issues.
7 twist ensures even if the twist is not perfect you can still make it work.
As for barrel life, I suspect that the barrel life will not be much greater then the 6.5-284 or 6.5Mystic 260AI family.
You will be running at higher pressures using relatively 'hot' powders like H4350 and Re17. No different then the 6.5 shooters and H4350 or H4831SC.
Recoil is a major consideration to me shooting F class. If not, I would go with a full house 7mm and push those 180gr Bergers to good effect. Unfortunately, my shoulder isn't up to that much fun.
When I studied the ballistics, costs and availability of components, I found that the 6.5 was the best balance for my needs. If they ever made an accurate 6mm bullet with a BC over 0.615 that could be pushed to 2900fps +, that would certainly get my interest.
But then barrel wear would be horrendous and I would be exactly where I am now.
I shoot the 6.5 cause I need all the help I can get....
Jerry
7 twist ensures even if the twist is not perfect you can still make it work.
As for barrel life, I suspect that the barrel life will not be much greater then the 6.5-284 or 6.5Mystic 260AI family.
You will be running at higher pressures using relatively 'hot' powders like H4350 and Re17. No different then the 6.5 shooters and H4350 or H4831SC.
Recoil is a major consideration to me shooting F class. If not, I would go with a full house 7mm and push those 180gr Bergers to good effect. Unfortunately, my shoulder isn't up to that much fun.
When I studied the ballistics, costs and availability of components, I found that the 6.5 was the best balance for my needs. If they ever made an accurate 6mm bullet with a BC over 0.615 that could be pushed to 2900fps +, that would certainly get my interest.
But then barrel wear would be horrendous and I would be exactly where I am now.
I shoot the 6.5 cause I need all the help I can get....
Jerry
I would not reccommend the 1:7. My own experience is bearing that out now, and i am finding I am throttling way back to achieve accuracy.
Anyone who has followed Cross-the-course shooting knows Robert Whitley. He made the following post on 6mmBR.com. He knows what he is talking about and he manages the 6mmhot.com website as well.
He makes the following commenstary:
Anyone who has followed Cross-the-course shooting knows Robert Whitley. He made the following post on 6mmBR.com. He knows what he is talking about and he manages the 6mmhot.com website as well.
He makes the following commenstary:
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
That is really a shame as we are unlikely to see any 6mm bullets with higher BC than what we have now.
Jerry
Jerry
Actually Jerry, if a Pratt & Wittney B rifling machine is used, the twist is created by using gears with extremely precise dimensions to vary the amount that a barrel is rotated and moved londitudinally. The cutter box stays stationary and the barrel is rotated and fed back and forth based on the gears that are used. I have seen this machine set-up and wondered how rifling was created to such exact dimensions... it is actually very simple yet there is no error... Mick read that comment and was hopping up and down! 
Many button processes use the pitch of the button bumps alone to guide the button down the barrel and as such, varying steel homogeneity will cause varying rates of twist down the bore... one of the issues with buttoning for sure, but then some button makers sell their barrels that fall outside of the tightest tolerances as something other than match grade.
Both processes produce good barrels, but twist precision done with EDM (nobody I know of with rifle barrels) proprietary barrel CNC (Bartlein) or the PW B machine (Border, Krieger, Obermeyer, McPhee) are as exact as they get.
Many button processes use the pitch of the button bumps alone to guide the button down the barrel and as such, varying steel homogeneity will cause varying rates of twist down the bore... one of the issues with buttoning for sure, but then some button makers sell their barrels that fall outside of the tightest tolerances as something other than match grade.
Both processes produce good barrels, but twist precision done with EDM (nobody I know of with rifle barrels) proprietary barrel CNC (Bartlein) or the PW B machine (Border, Krieger, Obermeyer, McPhee) are as exact as they get.
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- Location
- Lloydminster
The Coopers we sell in 6X47 have a 1:14
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Obtunded, thanks for the info.
Jerry
Jerry
