NEVER MIND -- I have a good Krieger 6mm Barrel
- Thread starter Nomo4me
- Start date
Re: How to determine if I have a bad Krieger 6mm bbl?
If you look in the 6mmBR cartridge guide, I believe that there is some discussion about the two bore sizes. As I recall, they were recommending the .236 bore for the Lapua Scenars which were said to be slightly smaller in diameter than some of the others. My 6mmBR barrel is a .237 and I have not had any issues but it might be worth measuring your bullets because I have found diameter variations of 0.0005 between manufactures in my 7mm with the A-Max being the smallest. I have also experienced blow ups when shooting the larger diameter bullets in a 1:8.5 twist .276 instead of a 1:9 twist .277 7mm barrel. It is probably well worth checking the diameters particularly since your 6X47 is going a lot faster than a 6mmBR with the same bullet and more velocity does seem to aggravate these issues.
If you look in the 6mmBR cartridge guide, I believe that there is some discussion about the two bore sizes. As I recall, they were recommending the .236 bore for the Lapua Scenars which were said to be slightly smaller in diameter than some of the others. My 6mmBR barrel is a .237 and I have not had any issues but it might be worth measuring your bullets because I have found diameter variations of 0.0005 between manufactures in my 7mm with the A-Max being the smallest. I have also experienced blow ups when shooting the larger diameter bullets in a 1:8.5 twist .276 instead of a 1:9 twist .277 7mm barrel. It is probably well worth checking the diameters particularly since your 6X47 is going a lot faster than a 6mmBR with the same bullet and more velocity does seem to aggravate these issues.
Re: How to determine if I have a bad Krieger 6mm bbl?
Ron. I agree completely. The Perfect Storm in a 7mm is an larger diameter 180 grain thin jacket bullet in a .276 1:8.5 twist 31 inch barrel at speeds in excess of 2900 fps. In a test, I lost 7 in a row on a relatively clean barrel. Fired the next 30 through a 277 1:9 31 inch barrel and didn't loose any. The 276 1:8.5 has been one of the most accurate barrels I've ever had on the gun but I've kept the speeds down at 2800.RonAKA said:
Re: How to determine if I have a bad Krieger 6mm bbl?
I was pushing those 88's hard with RL-17 at around 3500 fps. Honestly got a couple of groups in the low .3's before they started blowing up.
Funny thing that I dismissed at the range - my chrono read a couple of shots at 4000+ fps. I didn't notice any recoil or other pressure signs so discounted it as erratic chrono readings but my chrono has never done that with any other gun.
I'm wondering if the copper fouling could have played a role. I was weighing my charges of RL-17 so no error there.
That was 10 months ago.
The hack since rechambered my gun and I shot 20 Berger 108's through it at 3150 fps during the winter. Bore was badly fouled leading me to post about it in this thread.
I think the only thing to do at this point is send it to Krieger and ask them for their opinion and discard it if they think it's fine.
I appreciate learning from you guys here.
Mike
I was pushing those 88's hard with RL-17 at around 3500 fps. Honestly got a couple of groups in the low .3's before they started blowing up.
Funny thing that I dismissed at the range - my chrono read a couple of shots at 4000+ fps. I didn't notice any recoil or other pressure signs so discounted it as erratic chrono readings but my chrono has never done that with any other gun.
I'm wondering if the copper fouling could have played a role. I was weighing my charges of RL-17 so no error there.
That was 10 months ago.
The hack since rechambered my gun and I shot 20 Berger 108's through it at 3150 fps during the winter. Bore was badly fouled leading me to post about it in this thread.
I think the only thing to do at this point is send it to Krieger and ask them for their opinion and discard it if they think it's fine.
I appreciate learning from you guys here.
Mike
Re: How to determine if I have a bad Krieger 6mm bbl?
That's some interesting stuff... I wonder how often something like this creates blow-ups, but it's misdiagnosed as a problem with the twist rate?
TonyR said:
That's some interesting stuff... I wonder how often something like this creates blow-ups, but it's misdiagnosed as a problem with the twist rate?
Re: How to determine if I have a bad Krieger 6mm bbl?
Than answer to your question is "Sometimes Yes", depending on a number of factors. The person who explained it to me said that the Perfect Storm was a long barrel, a big charge of slow powder, a fast twist, a dirty gun, a long string, a thin jacket bullet, a hot day, and a couple of strings shot back-to-back after a long rain delay. My 31 inch 1:9 managed to blow up a 180 JLK that day but that is the one and only time with that barrel. This tight 1:8.5 didn't need much if anything to push it over the edge with thin jacket bullets; however, I have not blown up any Sierra, Cauterucio or Berger Thick Jacket bullets including a couple of long strings at over 3100 fps with a 7mm BooBoo out of a 31 inch barrel loaded with over 70 grains of powder.
Walt.queen_stick said:
Than answer to your question is "Sometimes Yes", depending on a number of factors. The person who explained it to me said that the Perfect Storm was a long barrel, a big charge of slow powder, a fast twist, a dirty gun, a long string, a thin jacket bullet, a hot day, and a couple of strings shot back-to-back after a long rain delay. My 31 inch 1:9 managed to blow up a 180 JLK that day but that is the one and only time with that barrel. This tight 1:8.5 didn't need much if anything to push it over the edge with thin jacket bullets; however, I have not blown up any Sierra, Cauterucio or Berger Thick Jacket bullets including a couple of long strings at over 3100 fps with a 7mm BooBoo out of a 31 inch barrel loaded with over 70 grains of powder.
Re: How to determine if I have a bad Krieger 6mm bbl?
If its just a bad chamber, couldn't you just have it set back an inch and rechambered by someone competent? Doesn't seem like there has been much wear on the rest of the barrel and it seems like you have plenty of velocity.
Mike.Nomo4me said:
If its just a bad chamber, couldn't you just have it set back an inch and rechambered by someone competent? Doesn't seem like there has been much wear on the rest of the barrel and it seems like you have plenty of velocity.
Re: How to determine if I have a bad Krieger 6mm bbl?
Tony I'm at a 26" bbl now. Setting it back would take it down to 25". This one also has the extreme stink of bad memories. I want a 27" bbled gun with good memories of a good interaction with a good 'smith.
Plus it fouls like hell. I broke in a Brux 10 twist 6dasher today. Plenty of copper for the first 5 bullets then it started purring.
Tony I'm at a 26" bbl now. Setting it back would take it down to 25". This one also has the extreme stink of bad memories. I want a 27" bbled gun with good memories of a good interaction with a good 'smith.
Plus it fouls like hell. I broke in a Brux 10 twist 6dasher today. Plenty of copper for the first 5 bullets then it started purring.
Re: How to determine if I have a bad Krieger 6mm bbl?
Tony - that's some sound advice, and I'm not taking away from that...
Nomo4me - I understand that it's cash out of your pocket, but you never know... a 23". 24" or 25" barrel may get you to a sweet spot... setting it back might work? I can understand how frustrating it must be in your situation, so I'd seriously consider the advice provided by some of our "senior" (not aged, but experienced
) members who have A LOT of experience with such situations, and get a new barrel.
One of the first things I learned in long-range BR, is that your mental game has to be there... if you're questioning your equipment, you'll never "settle in," which means you'll never be content with your results. Even if you win a relay, or win a match, you'll have a that thought that you could have done better if your equipment was up to par. That's kind of how I see it anyway... I've applied that way of thinking to other disciplines of shooting, and it's been a great benefit. Trust your equipment, and you'll be happy with your results. If you don't trust it, get rid of it! That includes a NEW barrel, which is unfortunate, because of the costs involved. That's just part of the quest for accuracy!
TonyR said:
Tony - that's some sound advice, and I'm not taking away from that...
Nomo4me - I understand that it's cash out of your pocket, but you never know... a 23". 24" or 25" barrel may get you to a sweet spot... setting it back might work? I can understand how frustrating it must be in your situation, so I'd seriously consider the advice provided by some of our "senior" (not aged, but experienced
) members who have A LOT of experience with such situations, and get a new barrel.One of the first things I learned in long-range BR, is that your mental game has to be there... if you're questioning your equipment, you'll never "settle in," which means you'll never be content with your results. Even if you win a relay, or win a match, you'll have a that thought that you could have done better if your equipment was up to par. That's kind of how I see it anyway... I've applied that way of thinking to other disciplines of shooting, and it's been a great benefit. Trust your equipment, and you'll be happy with your results. If you don't trust it, get rid of it! That includes a NEW barrel, which is unfortunate, because of the costs involved. That's just part of the quest for accuracy!
Re: How to determine if I have a bad Krieger 6mm bbl?
Walt
Depth and type of rifling may also have some effect on bullets blowing up (or not) Somewhere on this site is an interview with John Whidden and how he shoots 105 thin jacket VLDs at 3400fps(??) with his 243 Win. His results indicate that he is not blowing up many if any bullets and I wish I could find the interview but can't. Anyway, the gist of it as I recall was shooting coated bullets through a barrel with shallow canted lands such as a Broughton 5C. He didn't address twist but I know that many top shooters have enough barrels that they can use the slowest twist that will stablize their bullets in the current conditions so there may be some of that as well but I don't believe that he mentioned that specifically.
queen_stick said:
Walt
Depth and type of rifling may also have some effect on bullets blowing up (or not) Somewhere on this site is an interview with John Whidden and how he shoots 105 thin jacket VLDs at 3400fps(??) with his 243 Win. His results indicate that he is not blowing up many if any bullets and I wish I could find the interview but can't. Anyway, the gist of it as I recall was shooting coated bullets through a barrel with shallow canted lands such as a Broughton 5C. He didn't address twist but I know that many top shooters have enough barrels that they can use the slowest twist that will stablize their bullets in the current conditions so there may be some of that as well but I don't believe that he mentioned that specifically.
Re: How to determine if I have a bad Krieger 6mm bbl?
As a follow up:
Jon Beanland rechambered the barrel on this 6x47L and it now shoots beautifully and shows no more copper than any other rifle I own. It likes 108gr Bergers at 3150 fps via H-4350 and put 3 5 round groups into the high .3's Saturday while I was fireforming brass.
Problem was a rough throat all along.
Kudos to Jon Beanland of Oklahoma for being a superb smith in terms of quality, timeliness and communication.
As a follow up:
Jon Beanland rechambered the barrel on this 6x47L and it now shoots beautifully and shows no more copper than any other rifle I own. It likes 108gr Bergers at 3150 fps via H-4350 and put 3 5 round groups into the high .3's Saturday while I was fireforming brass.
Problem was a rough throat all along.
Kudos to Jon Beanland of Oklahoma for being a superb smith in terms of quality, timeliness and communication.
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