Page 3 of 3 FirstFirst 123
Results 31 to 41 of 41

Thread: Berger bullet failure test

  1. #31
    Join Date
    Jan 2004
    Location
    hou tx
    Posts
    31
    eric i have a large number of years in QA, don't want to tell how many cause i'm old. oh well you are going about this in a different manner than i would but you appear to be well on your way to getting to the answer. from all of the posts i believe that you are going in the right direction with the jacket thickness. if the jackets are failing then increasing there ability to hold together is a logical solution. it really matters not weather the temp or the type of rifling is the problem. if it doesn't work then you know one thing more than when you started and can try something else. i shoot your .224 75 gr vld from a kreiger cut barrel, i have had none of the problems listed in this post. i have found that shooting them at less than the ragged edge of the velocity envelope get me better groups. what you do with j-4 jackets is a marvel. i did find that i was getting more flyer's if i didn't lube the case necks when loading them but that was my problem and not the bullet. happy hunting you have an elusive pray in mind.

  2. #32
    Join Date
    Nov 2006
    Posts
    108

    Some perspective

    I've got no intention of 'mixing it up' on any of the technical issues discussed on this thread, but I would like to comment on the relevance, scope and implications of solving the bullet failure problem.

    Successful long range shooting is most easily achieved by pushing the highest BC bullet to the highest possible velocity while maintaining precision. Historically, bullet failure has been one of the key problems in achieving greater speeds with high BC bullets, especially in smaller calibers. Solving the failure problem raises the collective bar in long range shooting. However, bullet failure isn't the only problem. Other limiting factors are barrel life and more energetic (and safe) powder formulations. What I'm saying is:

    Advancing the technology of LR shooting is done by improving the entire system, one piece at a time.

    Dwelling on the details of why one explanation of bullet failure is or isn't precisely accurate doesn't interest me. It's been demonstrated by extensive and credible testing that thicker jackets solved the problem (or at least drastically increase the thresh-hold). OK, we've got it. What's the next problem?

    Eric indicated that the thicker jackets increased pressures, enough to blow primers. This could be the next problem to solve. Perhaps the thicker jackets will require a slower burning powder than what's typically used in the popular 6.5-284 cartridge. Maybe the slower burning powder, combined with more survivable bullets will result in a combination superior to (faster than) anything the 6.5-.284 could do before.

    Beyond the powder and bullet problem is the barrel wear gremlin. What options do we have for making longer lasting throats? Ceramics? Who knows.

    My point is that a long range rifle is a system. To improve a system, you have to strengthen the weakest link in the chain, and insure all the parts work together well. It used to be (in some cases) that bullet failure was the weakest link in the chain. Thanks to the testing that Eric reported on, this is no longer the case. We can now move on to the next problem, the next 'weakest link'.

    It's ironic from a historical point of view, that an improvement to bullet technology (more survivable jackets) may drive advancement in propellant technology. If I remember correctly, it was the advent of smokeless powder, and the high performance associated with it that caused bullets to require jackets in the first place. Will the chemists at Hogdens, Vita Vouri, or IMR even attempt to 'step up' and engage? The ball may be in their court now. If there is something that prevents them making better propellant, we should at least understand the limitations.

    I think Eric and Berger bullets is doing their part to advance the shooting sports by solving problems which will elevate the reliability of our projectiles at higher speeds. If further improvement of the 'shooting system' is to occur, it will have to be done by improving other parts of the system. I'm not saying that bullets are as good as they'll ever be, I'm just saying they're not the weakest link anymore.

    When Eric comes on these forums and shares results with us like he does, we should be supportive and grateful (as some of us are) that someone in the industry actually cares about making things better instead of arguing over the details. Of course it's acceptable, even encouraged to challenge ideas put forth on the forums. But when someone comes thru with a tested and proven solution, there's nothing to argue. As far as I'm concerned, we should simply say 'thank you', and go about attacking the next weakest link.

    -Bryan

  3. #33
    Join Date
    Feb 2003
    Location
    NE Louisiana
    Posts
    58
    Eric,

    I don't have it in for you. I have truly been trying to help.

    I came back into BRC through a link sent to me by Lynn Dragoman and that is the only reason I was aware of this discussion. It is good to see you are making progress on improving your bullets. Good luck.

    Henry

  4. #34
    Join Date
    May 2006
    Posts
    216
    Lynn,

    I appreciate your post. I do not have a bad opinion of Henry. We have disagreed before and likely will again down the road. I do not take these debates personally.

    I believe these exchanges help us all learn. Without Henry questioning the height of the lead in the nose we would not have considered it. Turns out it doesn't cause failure but what if it did? He shined a light on an area that was not previously considered.

    I have spent many years listening to everything. Just because I don't agree does not mean I do not take serious information seriously. I would be a fool not to. I look forward to more of Henry's thoughts along with the many others who engage these forums with a genuine desire to obtain and share knowledge.

    Regards,
    Eric

  5. #35
    Join Date
    Dec 2005
    Posts
    472

    Back woods perspective.

    I appreciate this thread and the contributers .
    I have been doing my own thing quietly on my own , with moly coating and bullet swaging for a very long time.
    Lot of fancy words spoken and technical stuff talked about here. Truth is it is giving me a headache .
    I learnt a long time ago that a rough barrel can blow up a light jacket.
    Cut rifle barrels can be very accurate but can also put too deep engraving on the bullet .
    Bullets do overheat and blow up and it is the jacket that explodes from getting too weak to contain the cetrifugal force from the rotation.
    However their is many different bullet designs , a jacket that is hollow at the base and exposing the core may act differently. A meplat may open a bit inducing a sudden increase in drag which will have a domino effect and explode the bullet just the same as hitting a hard target. The Ogive could bulge and fail causing a similar result.
    I believe that a quality coating of Moly Disulphide can help if the problem is marginal. If the problem is severe as in Bergers purposefull test conditions , then it will not stop it as far as I have observed .
    Because I coated some bullets for a friend that was having these same problems and it only improved it somewhat .
    In the end we lapped the barrel and dropped the velocity and with the coating it stopped the problem with those bullets anyway.
    I think that only indepth testing by a big organization like Berger , Sierra or Norma can really come up with exact reliable data in the long run.
    However I have never relied on the industry to tell me what is going on because sometimes they will keep it to themselves , its that competitive edge thing.
    Last edited by J. Valentine; 08-13-2008 at 07:39 PM.

  6. #36
    Join Date
    Aug 2008
    Posts
    1
    Fascinating post from one and all.
    Made me register with this forum.
    Sorry if I have missed this but two questions occur to me:-

    1. If the core weight was the same presumably the overall bullet weight of the thicker jacketed bullets was heavier? It would be interesting to reduce the core weight to give the same overall weight (probably what you have done in the production bullets) to see if the pressure effect is indeed jacket thickness related or simply bullet weight related.

    2. It would be interesting to know the distance the test was done at? Some of the blowups I have heard of have been well down range so testing at short range does not guarantee performance at long. Unless someone has data I would not rule out bullets warming due to air resistance. A back of envelope calc shows that if all the bullet's kinetic energy were turned to bullet heat the temperature rise would be a couple of thousand degrees. Fortunately for the bullet most of the energy will go to noise and warming the air but bullets do land very hot. At 1k I have seen a marker trying to pick up a ricochet which landed on the butt floor but dropped it saying "ouch" as it was still so hot. Even if the bullets do not gain heat outside the barrel the heat may still be spreading from jacket to core which will affect matters downrange.

    Mike

  7. #37
    Join Date
    May 2006
    Posts
    12
    Quote Originally Posted by mikebbh View Post
    Fascinating post from one and all.
    Made me register with this forum.
    Sorry if I have missed this but two questions occur to me:-

    1. If the core weight was the same presumably the overall bullet weight of the thicker jacketed bullets was heavier? It would be interesting to reduce the core weight to give the same overall weight (probably what you have done in the production bullets) to see if the pressure effect is indeed jacket thickness related or simply bullet weight related.

    2. It would be interesting to know the distance the test was done at? Some of the blowups I have heard of have been well down range so testing at short range does not guarantee performance at long. Unless someone has data I would not rule out bullets warming due to air resistance. A back of envelope calc shows that if all the bullet's kinetic energy were turned to bullet heat the temperature rise would be a couple of thousand degrees.
    Fortunately for the bullet most of the energy will go to noise and warming the air but bullets do land very hot. At 1k I have seen a marker trying to pick up a ricochet which landed on the butt floor but dropped it saying "ouch" as it was still so hot. Even if the bullets do not gain heat outside the barrel the heat may still be spreading from jacket to core which will affect matters downrange.

    Mike


    Mike has raised an interesting point....if the jacket is thicker it should mean less lead in the core. How is the bullet weight maintained? Is the bullet longer or is the ogive moved towards the tip.

    Also as a target shooter I now have regular Berger 6mm 108 BT and a couple of boxes of 6mm 108 THICK. I would assume that they should be no difference in accuracy between the two different jacket thicknesses?

  8. #38
    Join Date
    Dec 2005
    Posts
    472
    I am fairly certain that bullets get hot from air friction also so if the bullet is over heated in a rough barrel and subjected to deep engraving from a particular design rifling in combination with a thin jacket and quick firing that over heats the barrel , then a blow up can occur close or down range depending on many initial heating factors , bullet velocity and construction.
    I am fairly sure that the vapour trail that you can sometimes see in the air with the naked eye and especially in slow motion photography , is in part moisture being boiled by the bullet to air friction.
    As the jacket gets thicker there is less space inside for the core.
    There is few ways they could adjust the thicker jacket bullet to a specific weight. Use a longer jacket with the same ogive and get extra weight in the longer shank .
    If there is extra space inside the original meplat ( core depth ) then just add extra core weight and have the ogive fill out more ( less core depth )
    Use the same length jacket and core depth but use a blunter ogive that holds more weight . Reduce the angle of any boat tail so it holds more weight without increasing length .
    Last edited by J. Valentine; 08-21-2008 at 12:18 AM.

  9. #39
    Join Date
    May 2006
    Posts
    216
    Mikebbh,

    By making the jacket thicker we are moving the lead away from the greatest source of heat which is the rifling. The change in thickness is not great enough and in locations that would result in a considerable increase in the jacket weight. We do need slightly less lead since the jacket is heavier and we maintain end weight consistency (140 gr for example). However, lead being more dense means that proportionally we add more copper than the amount of lead we remove which results in a slight increase in the amount of lead in the nose. The difference is real but slight.

    We shot the bullets into the berm at Ben Avery Range in Phoenix from the 1,000 yard firing line. 2 and 3 folks with scopes observed each shot (besides the shooter). All of those who observed the shooting agree that the failures (blowups) occured at various distances. Some seemed to blow up immediately out of the barrel (accompanied by an unusual crack sound) while others produced vapor trails for a considerable distance but did not impact the berm.

    Bushpilotmexico,

    The weight of these bullets was 140 gr (with +/- weight variation consistent with a normal bullet run). The outside dimensions were exactly the same as our standard jacketed bullets as both these batches were run on exactly the same set up. No adjustments were made other than the use of a smaller seater punch.

    You are correct in your belief that the accuracy will be no different between the standard and thick 6mm 108 gr BT. The thicker jacket is meant only to ensure that you do not realize failures. Everything else is the same.

    There is one potential upside that might come from the thicker jacket. Our testing and focus has been on catostrophic bullet failures. These are bullets that do not make it to the target. We know that the lead melt and that once it does no jacket can take the pressure from a material as dense as lead spinning freely as a liquid at 250,000 RPMs. The key to our solution is to keep the core from melting in the first place. But what about the bullet that has only a slight softening of the core material.

    Could a core melt slightly enough that the bullet could hit the target but not where you thought it would? I believe the answer to this question is yes it can. The thicker jacket could both eliminate catostrophic failure and help reduce or eliminate some of the unexplained flyers especially those that occur when you were pouring the other shots one on top of the other. We'll have to wait and see.

    Regards,
    Eric

  10. #40
    Join Date
    May 2006
    Posts
    12
    Quote Originally Posted by Eric Stecker View Post
    Bushpilotmexico,

    The weight of these bullets was 140 gr (with +/- weight variation consistent with a normal bullet run). The outside dimensions were exactly the same as our standard jacketed bullets as both these batches were run on exactly the same set up. No adjustments were made other than the use of a smaller seater punch.

    You are correct in your belief that the accuracy will be no different between the standard and thick 6mm 108 gr BT. The thicker jacket is meant only to ensure that you do not realize failures. Everything else is the same.

    There is one potential upside that might come from the thicker jacket. Our testing and focus has been on catostrophic bullet failures. These are bullets that do not make it to the target. We know that the lead melt and that once it does no jacket can take the pressure from a material as dense as lead spinning freely as a liquid at 250,000 RPMs. The key to our solution is to keep the core from melting in the first place. But what about the bullet that has only a slight softening of the core material.

    Could a core melt slightly enough that the bullet could hit the target but not where you thought it would? I believe the answer to this question is yes it can. The thicker jacket could both eliminate catostrophic failure and help reduce or eliminate some of the unexplained flyers especially those that occur when you were pouring the other shots one on top of the other. We'll have to wait and see.

    Regards,
    Eric

    Hi Eric,

    You've perked my curiosity, I'm shooting a 6BR using your 108 BT bullets out of a 28" Krieger barrel 1 in 8 twist at a muzzle velocity of 2980 fps. From your experience what are the chances of the lead core actually melting at 100 yards out to 1000 yards at that velocity and twist?

    My friend was fortunate enough to get 2 boxes of your 108 THICK and at 100 yards in his Krieger 6BR is almost putting them in the same hole with no flyers at 300 yards he is getting less than 3/4" groups. Your theory about the molten core and the possible flyers is interesting but if the core was molten and the jacket holds together would accuracy suffer? Any flyer I have seen still seems to punch a clean hole.

  11. #41
    Join Date
    Dec 2005
    Posts
    472
    I just finished drawing down 2000 thick 6mm jackets from short 6.5 jackets to combat this very problem . Problem is that now the standard 6mm core will not fit the tapered jacket . So I will have to use a 22 cal core instead and hope I can get enough core inside the jacket to start the punch properly.
    Last edited by J. Valentine; 08-24-2008 at 10:04 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •