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Alastair
Guest
How would these tips affect a projectiles flight?
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Slight correction. At long range, those points *might* affect drop, resulting in a bit of vertical stringing. While the tips are distorted, if that distortion is about the same, they will also shoot to about the same height. We trim meplats because it is so terribly hard to visually evaluate what the distortion will cause.
To give a general answer to your question, the point of a bullet has a large impact on it's drag function. I've seen real-world tests where the BC of bullets like those varied by as much as .020 with a 10-shot group. IIRC, that's worth 4 inches of vertical at 1,000 yards, on top of whatever else is going on. Winning 10-shot groups are typically in the 5-inch region; that's just too much to give away.
To give a general answer to your question, the point of a bullet has a large impact on it's drag function. I've seen real-world tests where the BC of bullets like those varied by as much as .020 with a 10-shot group. IIRC, that's worth 4 inches of vertical at 1,000 yards, on top of whatever else is going on. Winning 10-shot groups are typically in the 5-inch region; that's just too much to give away.
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Alastair
Guest
Thank you Gents.
Unfortunately in the comp I shoot we are not allowed to meplat or point projectiles and I have noticed a differance of about 2 MOA in my 1000yrd elevation.
regards
Unfortunately in the comp I shoot we are not allowed to meplat or point projectiles and I have noticed a differance of about 2 MOA in my 1000yrd elevation.
regards
Alastair
The bullets you showed a picture of look like older Berger VLDs. (So having stuck my neck out, I imagine they're something completely different. It's just that I've seen plenty of the old Berger VLDs that looked like that.) I understand too that it is difficult to get bullets into Australia -- or really, the U.S. export laws make it hard to import from the States.
However, one thing you might try is to uniform the meplats, just for testing, to see if that is indeed part of your problem.
I do believe newer Berger VLDs are better on the meplat issue, and I'd go so far as to suggest skipping VLDs entirely, rather try a bullet with a high-number tangent ogive, or the new Berger hybrid designs.
VLDs are had to make consistently (manufacturing problem) and fussy to load. If you're anywhere near jamming them, you might try a .020+ jump, and see if the problem is minimized. My thinking here is that with some variance in the bullets, and some variance with your bullet seating technique and/or tools that are less than ideal, some of your rounds, in your rifle, might have a small jump, with others a small jam. That's about as bad as you can get with respect to varying pressure, hence velocity.
Even with this thinking, I find a 2 MOA spread hard to explain. If you don't mind, what is your sport, what sights are you using, how are you getting the powder charge (thrown or weighted), what caliber, etc. etc. And what is your group size, generally?
Even better would be to enlist the aid of an experienced shooter at your club.
The bullets you showed a picture of look like older Berger VLDs. (So having stuck my neck out, I imagine they're something completely different. It's just that I've seen plenty of the old Berger VLDs that looked like that.) I understand too that it is difficult to get bullets into Australia -- or really, the U.S. export laws make it hard to import from the States.
However, one thing you might try is to uniform the meplats, just for testing, to see if that is indeed part of your problem.
I do believe newer Berger VLDs are better on the meplat issue, and I'd go so far as to suggest skipping VLDs entirely, rather try a bullet with a high-number tangent ogive, or the new Berger hybrid designs.
VLDs are had to make consistently (manufacturing problem) and fussy to load. If you're anywhere near jamming them, you might try a .020+ jump, and see if the problem is minimized. My thinking here is that with some variance in the bullets, and some variance with your bullet seating technique and/or tools that are less than ideal, some of your rounds, in your rifle, might have a small jump, with others a small jam. That's about as bad as you can get with respect to varying pressure, hence velocity.
Even with this thinking, I find a 2 MOA spread hard to explain. If you don't mind, what is your sport, what sights are you using, how are you getting the powder charge (thrown or weighted), what caliber, etc. etc. And what is your group size, generally?
Even better would be to enlist the aid of an experienced shooter at your club.
A
Alastair
Guest
Thank you Charles for your response.
They are not Berger projectiles.
I have tried meplating the projectiles and that has improved the grouping but not the flyers. The thing is we are not allowed to meplat or point our projectiles in the competition I shoot.
Apart from the tips the base to ogive dimension and the bearing area dimension are very consistent (less than 0.002 difference). I seat long and then check with my comparitor prior to seating to my final ogive length. So I am confident I don't have one projectile jumping and the next jammed. Run out is typically less that 0.002".
I'm using aperture sites. I weigh my powder loads so that they are as spot on as I can make them with a digital scale that measures to 0.1 grn. I let my scale warm up, I don't use it near mobile phones, cordless phones, under fluro lights or in direct sunlight and make sure there is no drafts when I'm loading. I also calibrate before use and periodically re zero to take out scale drift. Cartridge is 308W. Cases are weighed and batched with the same number of firings. Flash holes have de deburred and primer pockets have been uniformed. Powder charge is determined from the best velocity SD that will still keep my projectiles supersonic at 1000yrds. I also have a barrel tuner of sorts. Grouping from other batches of projectiles is typically less than 1/2 MOA.
I'm sorry for not explaining more clearly, grouping of these projectiles is less than 2 MOA but there is close to a 2 moa difference in elevation between groups from this batch of projectiles (with the burrs) and my previous batch with much better points and a sharper boat tail.
They are not Berger projectiles.
I have tried meplating the projectiles and that has improved the grouping but not the flyers. The thing is we are not allowed to meplat or point our projectiles in the competition I shoot.
Apart from the tips the base to ogive dimension and the bearing area dimension are very consistent (less than 0.002 difference). I seat long and then check with my comparitor prior to seating to my final ogive length. So I am confident I don't have one projectile jumping and the next jammed. Run out is typically less that 0.002".
I'm using aperture sites. I weigh my powder loads so that they are as spot on as I can make them with a digital scale that measures to 0.1 grn. I let my scale warm up, I don't use it near mobile phones, cordless phones, under fluro lights or in direct sunlight and make sure there is no drafts when I'm loading. I also calibrate before use and periodically re zero to take out scale drift. Cartridge is 308W. Cases are weighed and batched with the same number of firings. Flash holes have de deburred and primer pockets have been uniformed. Powder charge is determined from the best velocity SD that will still keep my projectiles supersonic at 1000yrds. I also have a barrel tuner of sorts. Grouping from other batches of projectiles is typically less than 1/2 MOA.
I'm sorry for not explaining more clearly, grouping of these projectiles is less than 2 MOA but there is close to a 2 moa difference in elevation between groups from this batch of projectiles (with the burrs) and my previous batch with much better points and a sharper boat tail.
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I got confused with two things you've mentioned:
That's close to within bounds. Consider that a reputable stateside shooter found an 18-inch difference between bullets that had the points closed over ones that did not. This with side-by-side testing at 1,000 yards. Not typical, but it did happen. The point of this is to give evidence to the notion that yes, there can be that much difference from the point configuration alone.
If having a uniformed meplat does not rid you of the flyers, I'd say that is not the problem.
* * *
It sounds like you are making your own bullets. I don't do that, so am unaware -- at least practically -- of all the pitfalls one can encounter. Core slippage, voids, etc. etc. It might possibly be worth your time to post on the Competition Only forum to get the input of some experienced bullet makers, R.G. Robinett, Al Nyhus, etc. The question is, after all, a matter of competition bullets. This only if you are in fact making the bullets.
If they are commercial bullets, you can only count on the manufacturer for consistency -- more than one of us has been known to change suppliers for such inconsistencies. Finally, if you are for some reason stuck with these bullets, I don't know of any way to test for internal problems, all you can do is to sort for external variations. It also sounds like you know how to do that quite well.
Good luck,
That's close to within bounds. Consider that a reputable stateside shooter found an 18-inch difference between bullets that had the points closed over ones that did not. This with side-by-side testing at 1,000 yards. Not typical, but it did happen. The point of this is to give evidence to the notion that yes, there can be that much difference from the point configuration alone.
If having a uniformed meplat does not rid you of the flyers, I'd say that is not the problem.
* * *
It sounds like you are making your own bullets. I don't do that, so am unaware -- at least practically -- of all the pitfalls one can encounter. Core slippage, voids, etc. etc. It might possibly be worth your time to post on the Competition Only forum to get the input of some experienced bullet makers, R.G. Robinett, Al Nyhus, etc. The question is, after all, a matter of competition bullets. This only if you are in fact making the bullets.
If they are commercial bullets, you can only count on the manufacturer for consistency -- more than one of us has been known to change suppliers for such inconsistencies. Finally, if you are for some reason stuck with these bullets, I don't know of any way to test for internal problems, all you can do is to sort for external variations. It also sounds like you know how to do that quite well.
Good luck,
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Alastair
Guest
Thank you again Gentlemen.
No, I do not make my own projectiles and no we cannot use polymer tips.
As far as I understand it the organisation was trying to maintain a relatively level playing field by limiting the projectiles able to be used while still maintaining a large buying power so as to be able to bargain with manufacturers. Projectiles have been added to the permitted list over time but only under extenuating circumstances.
One of the local 1000yrd BR shooters has a Juenke machine which checks for internal defects and I'm about to contact him again to see if he will be able to check a few projectiles for me.
Thank you for your time
regards
Alastair
No, I do not make my own projectiles and no we cannot use polymer tips.
As far as I understand it the organisation was trying to maintain a relatively level playing field by limiting the projectiles able to be used while still maintaining a large buying power so as to be able to bargain with manufacturers. Projectiles have been added to the permitted list over time but only under extenuating circumstances.
One of the local 1000yrd BR shooters has a Juenke machine which checks for internal defects and I'm about to contact him again to see if he will be able to check a few projectiles for me.
Thank you for your time
regards
Alastair
D
dk hunt 14
Guest
I have seen bullets with the tips really crooked or jagged and they still shot 4 and 5 inch groups. I don't think the tips is the problem. Check your private messages. Matt
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Alastair
Guest
I'd rather not say at the moment, but I will say they are 30cal, 155grn boattails
You're getting too general for us. Brian Litz's book is very good.
http://www.appliedballisticsllc.com/Products.htm
http://www.appliedballisticsllc.com/Products.htm