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Barrel whip?
- Thread starter Eddie 359
- Start date
How the hell should we know?!
Test more on either side in enough quantity and manner of variables so as to allow us to at least make an educated guess.
“Are these three shots enough to tell anyone squat?”
Test more on either side in enough quantity and manner of variables so as to allow us to at least make an educated guess.
“Are these three shots enough to tell anyone squat?”
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Hope I didn’t make you too mad. I guess the question is does this kind of vertical grouping typically indicate barrel whip? Or is this typically a velocity difference? Or means nothing at all.
No it doesn’t indicate barrel whip. A barrel moves every time you fire. You get barrel whip with good groups as well as with bad groups.
Dont mean squat, could be you could be anything.
Do it agan an see if it repeats.
Do it agan an see if it repeats.
Be sure to understand the difference between "Barrel Whip" and the harmonic vibration that's at the heart of finding a "node" that give you consistent accuracy.
Yup. That's how it works and nothing really works unless it can be repeated. . . over and over.
Like others have said, your small test really doesn't indicate much, other than "MAYBE" your rifle likes the load at .040 off the lands. To verify, load up some more exactly the same at .040 off and see if you can duplicate (or come close) to that .286 group.
It may be that it likes that particular seating depth rather than the jump. Rather than load at exactly the same jump, it'd be better to load to exactly the same seating depth to verify.
Thank you for your reply. I still think a vertical grouping has a specific cause, and will continue to try and figure that out. I have 10 rounds already loaded, but the wind has been gusting at 30kn.
If you believe the three shot group, vertical usually (but not always) means a powder adjustment is needed.
Seating depth can tighten up groups. Looks to me that at that depth your load doesn't like it. But as others have said test them again, and try more than three shots to confirm what you have. Take it out beyond 100 yards.
Seating depth can tighten up groups. Looks to me that at that depth your load doesn't like it. But as others have said test them again, and try more than three shots to confirm what you have. Take it out beyond 100 yards.
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Thank you for your response. I completely understand sample size. The same powder load was used in both the over 1 MOA vertical group as the .286 group. The variable used in this very small testing was seating depth. All four of the projectiles in the vertical group are touching. The difference at the muzzle between the top and bottom of that group is very small. I compile and analyze data for a living. I look for clues in the data that elicit response. I believe this vertical group is a clue. I’m thinking of moving closer to the landing .005 and maybe away .005. I did see a velocity increase between .010 and .020 that I did not expect.
You’re attempting to connect dots that aren’t there.
It could have just as easily been your breathing or rear bag use that resulted in the vertical stringing.
Also, your velocity isn’t going to jump 30 fps from .010 to .020 but then drop as you moved to .040. It’s not going to do that with that slight of change in capacity, but then turn and go completely the other way when you continue to decrease capacity.
If you analyze data for a living, you should absolutely know that you’re chasing your tail trying to find signal in all this noise.
I’d also suggest not starting out saying you’re new to all this, but then correcting people when the answers are not connecting the same dots. It’s a quick way to not getting much help.
Found a very interesting article on precision shooting today. Secrets of the Houston Warehouse. The article mentions an “interesting phenomenon” were “if the bullets were seated a little short and powder charge was a bit on the light side, the groups formed vertically “.
I could make a list of at least 10 reasons the Houston Warehouse is completely different than the shooting you did above.
More dots that don’t exist.
Ignore the chatterboxes, they're just trying to confuse you with facts...
Difference in bto between bullet lots affects seating depth at the same jump length.
True, but I don't believe that was part of this discussion. The OP got his best group at .040 off. He should continue to experiment at .040 off. Now if he changes bullet lots then he will need to make adjustments. I guess I made the assumption that most folks don't use bullets with wild variation in bto. However I shouldn't assume.
Anytime my wife or I say "cool whip", we always reference this scene and say it like stewy. lol
The difference is that the distance to the lands is not fixed and is constantly changing over time as opposed to a seating depth that you control and can keep constant. It's the consistent seating depth that will give you more consistent results on paper.
Also, referring to one's jump being used, doesn't really tell anyone anything about the load configuration since we all tend to have very different freebore measurement and use different calipers to make that measurement. We can get a better idea of what your load configuration if we know the COAL rather than jump.
It's just better to think in terms of seating depth than in terms of jump since it's the seating depth that will determine jump anyway. . . .especially for OP's issue.
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The top Benchrest shooters in the world follow the lands as they erode , most times for proper Jam . Your theory makes for a variable jump/jam , not what a shooter is looking for . I realize a person may have magazine restrictions, etc . that limit COAL .
So you propose adjusting your die with every seating to accommodate variation in bullet BTO measurements? Or do you sort bullets first so that they are all the same? Also if you don't know or measure distance to lands, how do you know how much to adjust seating depth or even where to start seating?
I agree with you that once seating depth is established (by determining best jump to lands), consistency is critical to consistent performance. But you have to find the sweet spot for jump and establish seating depth from that. As the lands wear and move forward, if accuracy falls off you can adjust seating depth to get back into the jump sweet spot.
So back to my original statement what's the difference? You have to establish the best jump during your load development and that establishes the seating depth. When reloading we don't continue to measure distance to lands we check bullet BTO and CBTO to verify the seating depth is the same as when we first developed the load.
Also load development is a singular thing. Its singular to your rifle, presuming that a load that works well in one rifle will also work well in another if we all know the CBTO is just silliness.
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Yes, that's true for those to are touching or jamming into their lands. When you're jumping to the lands. . . not so.
Yes, I sort bullets so that I get that uniformity when seating. . . especially when I'm using bullets that a lot of variation, like with the BTO measurements. In fact, I don't sort by BTO since there can be a lot of variation between the BTO measurement and the measurement between the base and the contact point of the seating stem. So I sort by the latter using a comparator insert that matches the contact point of my seating stem. This gives me really consistent seating depths, which is way more important than the variation the CBTO's make to distance to the lands.
I only measure distance to the lands using CBTO to find an initial starting point (like .010 off the lands) and thereafter to track the throat erosion. Once I've found the starting point, I focus on seating depths.
Yes, when accuracy falls off, that's when I'll adjust seating depth as needed. But how far the jump is at that point is irrelevant. Or maybe I may decide to look for a different accuracy node with a longer COAL, which would of course bring me closer to the lands. But I'd still not be focused on jump unless that longer COAL causes me to touch or jam the lands, which is not what I would want.
No, I don't establish the "best jump", I establish the best seating depth that doesn't touch or jam the lands.
Agree. In my case, in order to get a more accurate seating depth measurement, I measure using a comparator insert that matches my seating stem contact point for the sorted bullets used. Checking seating depth with standard CBTO measurements is ok, just won't result is as uniform seating depths. And for many shooters, that's good enough.
Agree!! That goes for jump as well and why it's best a reloader to state the COAL rather than CBTO or Jump, so that other reloaders can figure out just what the actual cartridge configuration might be as it relates to their own chamber.
Well we do agree on some things and disagree on others. You obviously have your method that must work for you. However, it seems backassward in some ways to the methods I use to develop my loads and I'm too many years into my method to change it.
So out of curiosity, if the OP posted his COAL, how would that assist you in giving him sound advice?
Who said the OP was using bullets with wild variance in bto? Do you not get that the base of the bullet exits the barrel last? The OP’s .040” off the lands is only relevant because it translates into seating depth. Another lot of bullets might be .020” longer in bto and setting jump length at .040” may or may not replicate the accuracy.
Wait! What?? The fat end of the bullet exits the barrel last?
Who knew??No one said the OP was using bullets of varying BTO, but it is a significant contributor to varying seating depth. However you keep bringing up different lots of bullets and varying length that effect seating depth. So, yes we agree, seating depth varies with varying BTO.
Exactly!!
Well if another lot of bullets is .020" longer and accuracy goes to shit, then he will have to start over with jump and re-establish a new seating depth. Hopefully, in his original development he found a jump sweet spot that is very forgiving to jump variation and that won't be necessary. But who knows with a single test of 3 shot groups? Maybe barrel whip is the problem here
You sure the fat end doesn't exit first??
Well, if it ain't broke, don't try to fix it.
OP has listed jumps from .010 to .040 and was asking about the vertical he got with .010 and if it had anything to do with barrel whip. Neither his COAL's or his jump is useful in advising him any about his question regard barrel whip. My response (in post #6 of this thread) was to encourage him to find out (do some research) what the difference is between "Barrel Whip" and the harmonics that we all try to tune out loads to; because they're not the same thing. And barrel whip is not what causing that vertical with that .010 off the lands as barrel whip occurs after the bullet has left the muzzle. It's the barrel time of the bullet that's not in time with the harmonics of his barrel. I don't know if the OP can understand this if he doesn't know the difference.
COAL could help answer other questions in terms seating depth as it relates to things like barrel time, pressure, powder charge, velocity, etc. And if someone is interested using OP's particular load specs, COAL will help determine seating depth and how that might fit into their particular chamber, where amount of jump does not.
Wait! What?? The fat end of the bullet exits the barrel last?
No one said the OP was using bullets of varying BTO, but it is a significant contributor to varying seating depth. However you keep bringing up different lots of bullets and varying length that effect seating depth. So, yes we agree, seating depth varies with varying BTO.
Exactly!!
Well if another lot of bullets is .020" longer and accuracy goes to shit, then he will have to start over with jump and re-establish a new seating depth. Hopefully, in his original development he found a jump sweet spot that is very forgiving to jump variation and that won't be necessary. But who knows with a single test of 3 shot groups? Maybe barrel whip is the problem here
You sure the fat end doesn't exit first??
You’re the one who brought up the wild variance.
Well, if it ain't broke, don't try to fix it.
OP has listed jumps from .010 to .040 and was asking about the vertical he got with .010 and if it had anything to do with barrel whip. Neither his COAL's or his jump is useful in advising him any about his question regard barrel whip. My response (in post #6 of this thread) was to encourage him to find out (do some research) what the difference is between "Barrel Whip" and the harmonics that we all try to tune out loads to; because they're not the same thing. And barrel whip is not what causing that vertical with that .010 off the lands as barrel whip occurs after the bullet has left the muzzle. It's the barrel time of the bullet that's not in time with the harmonics of his barrel. I don't know if the OP can understand this if he doesn't know the difference.
COAL could help answer other questions in terms seating depth as it relates to things like barrel time, pressure, powder charge, velocity, etc. And if someone is interested using OP's particular load specs, COAL will help determine seating depth and how that might fit into their particular chamber, where amount of jump does not.
Mtang is a fucking troll.
Wild variance. Not just typical variance. Wild variance. Now go away.
Confused on this comment - Jump/Seated depth??? what the dif?
Also, I am trying to work up loads for 6.5CM. I am having to UNLEARN! Well over 100 rounds in this new gun. ES, Accuracy, MOA, velocity, bullet type, seating depth, powder amount/type, burn rate as function of relative factors ( Superformance ). What seems to repeat is ES not falling on best MOA. Velocity increases with Superformance with greater jump. Ramshot Hunter is more predictable but at times I get better MOA with Superformance. All bullets are 140 grn, Berger, Nosler, and find little MOA benefit one over the other. What I feel is different, close to lands has been many shooter's best rounds on other calibers but it seems to be the opposite to some extent on 6.5CM. Also not unlearning but trying to better understand, Superformance burn rate versus all factors makes any load not follow typical load development because anything effecting the entire time of burn and the relative rate of burn at the moment and the relative position of the bullet and the push at that moment make a large difference in many of the accuracy variables. As a result, any single load factor I believe will change velocity, harmonic, and other factors on the target. Yet the powder performs stable temperature wise except one new comparison I have been following. Just where on my barrel is the highest temperature after say 20 rounds. If in the middle, or the end or chamber area is the hottest, what does that mean in relation to accuracy and where the burn rate is pushing the hardest?
We know that seating variations affect group size, and most probably there are multiple effects, such as barrel time and bullet alignment. But comparing two groups, whether 3 or 5 shots, really doesn't mean much. I would worry about trying to duplicate the 0.040" depth results.
BTO variance. If you have, say .007” which I have seen within one box of Hornady ELD-M, then seating to the same jump length will result in a .007” variance in seating depth. So if you want to be perfect, you can compensate for this by adjusting the bto for each round.
Seating Depth: The distance the base of the bullet is measured below the mouth of the case. The further out the bullet is seated the more case volume is available for the powder and the amount of volume per particular powder weight effects the pressure/velocity.
Jump: The distance from the bearing surface to the lands of the chamber as measured on the ogive. That distance will change as the throat erodes, and at some point, the throat erodes enough to effect the pressure curve and change the barrel timing.
Changing the seating depth with change the jump respectively. The jump with change without changing the seating depth. . . as the throat erodes.
Seating depth, where you're dealing with the case volume and powder performance, has a major factor in effecting the pressure curve and getting consistent accuracy. Bullet jump has very little to do with effecting the pressure curve unless one is touching or jamming the bullet into the lands.
There's a series of articles on jump at the Precision Rifle Bog that if you haven't already read them, you should do so and should help with answering questions about jump:
More Bullet Jump Research!
This is the 4th article in a series on some new research on bullet jumps. Here is a recap of the pr...
precisionrifleblog.com
The hottest temperature on your barrel is always at the front and cools down moving to the muzzle. It's that extreme heat the causes fire fracking and the throat erosion.
Though burn rate is often emphasized, it's not the only factor on how the pressure performs in the chamber. The heat index is also a key factor effecting the pressure curve.
Take a close look at the details in pic below from a load of mine as depicted by the QuickLoad app. The graph on the bottom left should give you a good idea how powder burn and pressure progresses down the barrel.
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