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Thread: Lt 32

  1. #16
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    Thumbs up Got others stashed

    Quote Originally Posted by adamsgt View Post
    Only one?
    Right... HA ..!

    Still got a GOOD Stash of "various" 8208's that I'm allllllllright with... The LT-32 is just to "play" with a bit...:-)

    Didn't pay $230 bucks Haz an Shipping for the 8208's back in the day... That's for SURE..!
    cale

  2. #17
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    Thumbs up Well said.

    Quote Originally Posted by mks View Post
    I think tuning for each yardage can make a difference. A different bullet or charge can be inconvenient, but a different front/rear rest location for each yardage can accomplish the same thing, depending on the dynamics of your system. Cheers,
    Keith

    Keith, thanks for reminding everyone that they must tune for the specific yardage. As I read this thread where more than one shooter suggested that a specific bullet would shoot good at say 100 yards but would not shoot at 200. Maybe it ain't the bullet: huh?

    So lets say that after winning the 100 yard agg in the morning, the shooter expects the same load to shoot at 200 only to find his group strings vertically showing the rifle completely out of tune even though ambient temperature is unchanged. So,,,, if temp and density altitude are the same, why would a change in tune be necessary? Nothing changed! Yes it did 'Bub' you changed yardages.

    Remember, you must tune for the specific yardage. This is another reason why using a tuner is so simple and convenient. No need to carry three different loads to the line. With a tuner you can often bring the rifle right in tune with a quarter turn in one direction or the other. The powder charge never needs to change. Only in recent years have I understood why one must tune to the specific yardage.

    Hope this helps someone.

    Later,

    Gene Beggs

  3. #18
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    Quote Originally Posted by Gene Beggs View Post
    Only in recent years have I understood why one must tune to the specific yardage.
    Perhaps I have missed some thread, but could you elaborate on why you now have arrived at this conclusion?

  4. #19
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    Quote Originally Posted by HopeToBe View Post
    Perhaps I have missed some thread, but could you elaborate on why you now have arrived at this conclusion?
    Its called WARPS. Space WARPS, time WARPS, barrel WARPS and then our mind WARPS.

    The first three shots go exactly through the same hole, the fourth shot goes out then the fifth shot goes exactly back through the original hole? Ever wonder about that? Think about it.

    What did the shooter do on shots one, two, three and five that they did not do on the fourth shot??

  5. #20
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    Fwiw

    Quote Originally Posted by Tim Singleton View Post
    What do you look for in a new barrel if you think it maybe junk? Haven't had a bore scope long I can definitely see the copper when I don't brush enough. Other than that I really don't know what to look for
    7 years ago I bought a LV 6mm barrel from a maker just ramping up its benchrest barrel production. I had it chambered and then shot it. For 100 rounds I literally couldn't get two bullets to touch one another. In the meantime I had acquired a borescope. I looked inside from both ends and the barrel finish was terrible with lots of tool marks, gouges, nicked lands and inclusions...looked like black pepper on white paper...they were everywhere. I contacted the maker and they replaced the barrel and gave me a second to compensate me for the cost of the chamber job on the bad one. Very up front and nice of them. The little voice in the back of my head has never stopped asking why such a poorly finished barrel ever made it into a benchrest shooters hands. All they had to do was look. I've bought from them subsequently with no issues, but regardless of who's barrel it is I look inside on getting it.

  6. #21
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    Quote Originally Posted by glp View Post
    7 years ago I bought a LV 6mm barrel from a maker just ramping up its benchrest barrel production. I had it chambered and then shot it. For 100 rounds I literally couldn't get two bullets to touch one another. In the meantime I had acquired a borescope. I looked inside from both ends and the barrel finish was terrible with lots of tool marks, gouges, nicked lands and inclusions...looked like black pepper on white paper...they were everywhere. I contacted the maker and they replaced the barrel and gave me a second to compensate me for the cost of the chamber job on the bad one. Very up front and nice of them. The little voice in the back of my head has never stopped asking why such a poorly finished barrel ever made it into a benchrest shooters hands. All they had to do was look. I've bought from them subsequently with no issues, but regardless of who's barrel it is I look inside on getting it.
    Thank you. That helps

  7. #22
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    Quote Originally Posted by HopeToBe View Post
    Perhaps I have missed some thread, but could you elaborate on why you now have arrived at this conclusion?


    It isn't easy to explain and it took me several years to understand it. It's a thing called positive compensation. I'm not very good at explaining things like this. I hope Keith Sharp (MKS) can help us out on this one.

    Gene Beggs

  8. #23
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    Quote Originally Posted by Tim Singleton View Post
    What do you look for in a new barrel if you think it maybe junk? Haven't had a bore scope long I can definitely see the copper when I don't brush enough. Other than that I really don't know what to look for
    This particular barrel looked real good, nice even finish. Very small tooling marks(might not be the correct term). The lands had very fine marks. Looked good. Cleaned up real good. At about 400 rounds. It would shoot 9-10 rounds and then you would get heavy bolt lift. Clean up good. Then heavy bolt lift. The group would also open up. A lot of 4 and 1 groups. Myself and several others checked equipment. Did this. Did that. At 500 rounds. I had had it. So being early spring. Let's get in there and get a good look. Looks good. Used patch out overnight. Looks good. Pulled out Iosso. Tried patches first. Cleaned up good. Looked good. Then I remembered seeing Jack N. using Iosso with a blue brush. So I did that. Scrubbed about 20X. A bunch of patches. Cleaned it out real good. Then took a real good look. nice and slow. same as always. I noticed 2 lands that the edges were not parallel. 2" in for about 8" the edges would get narrow. Just so ever slightly. The top and bottom.
    The other thing. Fire cracking at about 400 rounds. Ever so slight. Thought that was normal. But, I don't load hot.
    So the bore scope paid for itself.
    I did shoot that barrel one more time in a score match. Same thing. 8-10 rounds heavy bolt lift.
    Put the old barrel back on. Has over 3000 rounds. WE were back at it. Very happy at the last Score match. Last 2 Varmint shoots. 200-200. 192-200(But, 4 shoots were where I aimed sooo........). All good again.
    Time to find a tune on the new barrel.

  9. #24
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    Quote Originally Posted by Gene Beggs View Post
    It isn't easy to explain and it took me several years to understand it. It's a thing called positive compensation. I'm not very good at explaining things like this. I hope Keith Sharp (MKS) can help us out on this one.

    Gene Beggs
    Gene,
    I'll give it a "shot." If every cartridge in a group produced the same muzzle velocity and bullet exit time, compensation would not be required. But if we take as a given that there will be a range of velocities and bullet exit times within a group, we know from external ballistics alone that if the bullets are launched at the same angle, the slower bullets will hit the target lower. To get them to hit the target at the same elevation, we want to point the muzzle higher for the slower bullets. How do we know which bullets are slower? They are the ones that also travel through the barrel slower and have a later bullet exit time. How do we achieve compensation without knowing a priori which bullets are slower? We tune the system so that the muzzle angle is rising throughout the interval when all the bullets exit. For perfect compensation, the muzzle needs to be at just the right angle to offset the extra drop that occurs for the slower bullet at the distance we are shooting. At longer ranges, we need the muzzle angle to be higher for the slow bullet than at short range. Thus the muzzle angle must be increasing faster, because the delay time for the slow bullet is the same. VarmintAl shows a nice graph of this principle for a 22RF at 50 and 100 yards. I hope he doesn't mind me attaching it here.Click image for larger version. 

Name:	Trajectory 22LR 50&100.jpg 
Views:	255 
Size:	21.2 KB 
ID:	15314

    Geoffrey Kolbe wrote a nice article about compensation here: http://www.geoffrey-kolbe.com/articl...g_a_barrel.htm

    I think of tuners as fine-tuning the high frequency noise out of the muzzle angle path. Changing yardages requires a substantial change in the overall angular velocity of the muzzle. In principle, this could be done by moving the tuner (a lot), but I choose to make the big change some other way (e.g., moving the forend in the front rest) and keep the tuner for fine-tuning, so that I don't lose track of multiple turns.

    Hope this helps,
    Keith

  10. #25
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    Thanks Keith

    See what I mean guys; Keith can explain things perfectly while I'm thinking about it.

    Thanks again Keith.

    Later,

    Gene Beggs

  11. #26
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    Which direction do you move the forend? Further forward or move backward? What amount of movement ?

  12. #27
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    Quote Originally Posted by Tim Singleton View Post
    Which direction do you move the forend? Further forward or move backward? What amount of movement ?
    No guarantees, but usually backward. My 200 yard position was 2" back from the 100 yard position. You need to do ladder tests at multiple positions to figure out the best position for each yardage.

  13. #28
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    Dec 2009
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    Quote Originally Posted by mks View Post
    Gene,
    I'll give it a "shot." If every cartridge in a group produced the same muzzle velocity and bullet exit time, compensation would not be required. But if we take as a given that there will be a range of velocities and bullet exit times within a group, we know from external ballistics alone that if the bullets are launched at the same angle, the slower bullets will hit the target lower. To get them to hit the target at the same elevation, we want to point the muzzle higher for the slower bullets. How do we know which bullets are slower? They are the ones that also travel through the barrel slower and have a later bullet exit time. How do we achieve compensation without knowing a priori which bullets are slower? We tune the system so that the muzzle angle is rising throughout the interval when all the bullets exit. For perfect compensation, the muzzle needs to be at just the right angle to offset the extra drop that occurs for the slower bullet at the distance we are shooting. At longer ranges, we need the muzzle angle to be higher for the slow bullet than at short range. Thus the muzzle angle must be increasing faster, because the delay time for the slow bullet is the same. VarmintAl shows a nice graph of this principle for a 22RF at 50 and 100 yards. I hope he doesn't mind me attaching it here.Click image for larger version. 

Name:	Trajectory 22LR 50&100.jpg 
Views:	255 
Size:	21.2 KB 
ID:	15314

    Geoffrey Kolbe wrote a nice article about compensation here: http://www.geoffrey-kolbe.com/articl...g_a_barrel.htm

    I think of tuners as fine-tuning the high frequency noise out of the muzzle angle path. Changing yardages requires a substantial change in the overall angular velocity of the muzzle. In principle, this could be done by moving the tuner (a lot), but I choose to make the big change some other way (e.g., moving the forend in the front rest) and keep the tuner for fine-tuning, so that I don't lose track of multiple turns.

    Hope this helps,
    Keith

    This helps, although I might be missing the big picture. Gene was kind enough to explain this to me a few years ago and this makes perfect sense to me. But to put it in another way. If we tune at 200 there is no need to re-tune it to 100. But a 100 yard load might not perform well at 200?

    Or, of course, I might be a slow learner after all.

  14. #29
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    Quote Originally Posted by HopeToBe View Post
    If we tune at 200 there is no need to re-tune it to 100. But a 100 yard load might not perform well at 200?
    Compensation does tend to work this way, i.e., proper tuning is more critical as yardage increases. A rifle tuned for 200 won't be terrible at 100, but a 100 yard tune could be awful at 200. The take away message, though, is that each yardage needs its own individual tune.

  15. #30
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    "Compensation does tend to work this way, i.e., proper tuning is more critical as yardage increases. A rifle tuned for 200 won't be terrible at 100, but a 100 yard tune could be awful at 200. The take away message, though, is that each yardage needs its own individual tune."

    Since this thread has turned into a tuning thread - I assume it is ok to ask this question:
    One of my traveling partners and I always argue(discuss) about this; Are there separate tunes for windy vs calm days?

    I think yes - but could be completely wrong. I can also see compensation working for this. If one tunes for "windy" days = it will still be ok on calm days (but not as good as the one who tuned in the calm). If one tunes on calm days = that same tune could be terrible on windy days. Again, this is just what I think and have not done any tests. Just looking for others who may have tested to confirm or disprove this idea.

    The wrench in all of this is still how well our brain is picking up on the conditions. Which (maybe) compensation fits also??? Our brain has to be so much more focused at the longer distances and/or when the conditions worsen. A slight loss of focus (missed an angle change - missed a tail movement, etc) could result in a "bad" shot which may lead some to blame on tune. I think knowing when you missed conditions verses having a "bad" tune is a huge hurdle to cross to be able to get to that "next level" of shooting. A lot easier typed (said) than done.

    Very interesting thread - thanks to all those who are writing.
    Last edited by Apollo; 08-28-2014 at 05:40 PM.

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