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desert deuce
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Re: bullet tip

Post by desert deuce »

Interesting, interesting...

Questions Dave, speaking of weight distribution and diameter of ogive???

Is it true that a bullet in flight travels nose up rather than in line with the trajectory post trans sonic and after reaching apex?

Is there an ideal balance point central to the length of the bullet that may be beneficial, say 51-54% of weight in front half?

Also, the diameter of the ogive forward of that balance point, should it be bore diameter or slightly less, if less how much?

Your consideration appreciated.
Sometimes you get the chicken, and sometimes you get the feathers!
SchuetzenDave
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Re: bullet tip

Post by SchuetzenDave »

You first must have gyroscopic stability to have accuracy even at short distances.
This is dependent primarily on matching the appropriate length of your bullet to your barrel's twist.

For longer distance shooting dynamic stability becomes more important - i.e. where the center of balance of weight is along the length of the bullet.

The yaw is stabilized even with the weight further back on spitzer bullets and they are successful for shooting out to 300 yards but the angle of yaw is too much to shoot the bullets out to a 1,000 yards.

For long range shooting the weight distribution needs to be more balanced and this is done by having a heavier nose such as a Creedmoor, Postell, or
Elliptical nose.

Paul Jones also center balanced his bullets by cutting deeper and wider grease grooves to compensate in materials lost in forming the nose at the front.

Bullets with poorer center of balance yaw more and become more susceptible to crosswinds.
Tomklinger
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Re: bullet tip

Post by Tomklinger »

Gentlemen,
This is also why I shoot cup base elliptical p.p. bullets on my original Ballard Long Range 44/100. It has 1 in 20 twist. It needs weight forward and 1300 fps to stabilize at long ranges….
Tom k
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Don McDowell
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Re: bullet tip

Post by Don McDowell »

Tom bring the length of the bullet down to 1.3 in. long and you'll see the preformance of the bullet go way up at all distances , and it won't matter cup base or flat base.
Figured that out one day trying to figure out what was giving so much fits trying to get my 44-77 to do well at ranges beyond 800. Sitting at the desk staring at bullets, and suddenly it hit me. That original bullet pulled down from a 44 creedmoor bullet was pretty short compared to some of the modern renditions available. Grabbed the calipers and well what do you know,,, 1.3 inches...
AKA Donny Ray Rockslinger :?
Tomklinger
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Re: bullet tip

Post by Tomklinger »

Thanks Don,
I’ll try 1.3. I’m shooting a 530gr bullet at present, it’s 1.4 in length. The reason I went that long is that I wanted to keep the velocity down around 1300 to 1350. I don’t see any stability issues, but that doesn’t mean there aren’t any. Rifle has VERY good accuracy. When I shot a 500gr, the velocity went up to 1420 and my group opened up a bit. I think you get higher velocity in slower twist barrels….my practice range is 750yds…
Tom
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Don McDowell
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Re: bullet tip

Post by Don McDowell »

Tom a cross wind something above 5 mph will tell the tale especially when the distance gets past 800
AKA Donny Ray Rockslinger :?
Tomklinger
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Re: bullet tip

Post by Tomklinger »

I’ll mold up some 1.3’s and see what they do at my practice range, thanks for your input!
Tom
ian45662
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Re: bullet tip

Post by ian45662 »

I have a 38 caliber 1.47” long elliptical bullet that I will be shooting in a long range match next weekend. 12 twist barrel. Some people tell me that they are plenty stable and some say they arnt. I am curious so I am going to possible throw a match away just to see for myself. Camp Attubery usually has some pretty bad winds so it should be a great test. They do seem to hit the 200 yard target straight but I know that doesn’t mean much for 900 and 1000 yards. Depending on how this goes might just dictate which rifle I will use at raton.
gunlaker
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Re: bullet tip

Post by gunlaker »

Ian you've probably seen this, but just in case you haven't you might find it interesting. Some of Dan's old results with fast twist .38's.

https://bpcr.net/site_docs-results_sche ... bility.htm

Of course nothing works better than shooting it and seeing the holes for yourself.

Chris.
ian45662
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Re: bullet tip

Post by ian45662 »

gunlaker wrote: Fri Jun 03, 2022 8:00 am Ian you've probably seen this, but just in case you haven't you might find it interesting. Some of Dan's old results with fast twist .38's.

https://bpcr.net/site_docs-results_sche ... bility.htm

Of course nothing works better than shooting it and seeing the holes for yourself.

Chris.
Actually no I have not….. very interesting. I will have my pit crew take pictures of the holes in the paper. Maybe we will be able to tell if they have wobble or not
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desert deuce
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Re: bullet tip

Post by desert deuce »

I recall bullet imprints on target faces that were a figure 8 at 800-900 & 1,000 yards, same day same rifle, etc. Apparently due to yaw.

Presuming that the base of the bullet passed through the target last and the fact that the base of the figure 8 seemed slightly larger and varied as to location on the bullet imprint (and the presumption that even in downward trajectory the bullet travels nose up) on the face of the target.

All were grease groove bullets and I don't recall whether Dan was using a 45-90 or a 45-100 or twist, etc.

With that said Ian, maybe take photographs at all distances with the idea for the pit crew to be alert for figure 8 marks on the target face.
Sometimes you get the chicken, and sometimes you get the feathers!
ian45662
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Re: bullet tip

Post by ian45662 »

We will get pictures at each distance and see what is going on. I will be really curious to see how much more dope I will have to give in order keep these things on paper…. If they will fly true that is.
gunlaker
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Re: bullet tip

Post by gunlaker »

I thought I'd add this neat picture to this thread. It's a recent practice target shot with my Shiloh #3 in .40-65 with the same midrange and silhouette load I've been using for a few years. The bullet is a 40940M5 which is 1.4" long. Dan T. mentioned that this bullet is sufficiently stable for midrange in a .40-65, but not by a huge margin. Theoretically it's less stable in my 1:16 twist .40-65 than my 458535M1 when shot in a 1:18 twist .45-70. I'm comfortable with it as It has always shot well in the wind. It managed the second highest target at 600 at Byers on a very windy day a few years back for example.

On this ram there are 21 hits out of 22 shots taken, wind was variable with the L->R component going up to 10-12 mph with random tail wind thrown in. The target was shot holding off zero, 3 or 6 minutes using the mil dots on my 23" MVA scope depending on what the flags showed. What I find kind of neat is that the bullet splatters mostly point to the left indicating that the bullet was nosing into the wind. The most extreme "left" splatter is the shot on the nose where the wind picked up and nearly blew me off. The splatters that point down are likely when the wind let up.

If you see oval holes in paper I don't think it necessarily indicates instability if the nose is always offset about the same, and into the prevailing wind. If they are totally randomly oriented I'd be switching bullets :-).

Chris.

http://www.bcsingleshot.com/Photos/Ram-40-65.jpg
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Distant Thunder
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Re: bullet tip

Post by Distant Thunder »

Chris,

I have been thinking much the same thing since the spring match at Lodi this year. A lot of people noted tipping as the bullets passed through the target. I noticed that some of Brent's bullets were tipped and he shot very well, winng the match. He was shooting a prolate that is 1.457" long in his 16-twist 1877 Sharps. That bullet would have been spinning plenty fast enough to remain stable.

I think some of the tipping was the bullets running with their points into the wind gusts. Or they may just not have had time to settle back down after being hit with a really strong gust just before the target. Either way being tipped as they hit the target does not mean they were wobbling the entire distance!

Matt expressed concern about his bullets being tipped and perhaps being too long, but everything I know says his bullets should be stable in his 18-twist.

It's my understanding that bullets will track on the trajectory, but with their noses SLIGHTLY high and into the direction of spin, as long as they are not over spun. That is one of the problems with spinning a bullet too fast, it will fly with its nose increasingly high in relation to the trajectory as they descend through the downward part of the arc because they don't track. That would reduce the BC of the bullet by exposing more of the side of the bullet to air resistance. If a bullet does not track on the trajectory it is generally considered a bad thing for long range shooting.
Jim Kluskens
aka Distant Thunder
kwilliams
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Re: bullet tip

Post by kwilliams »

I have always wondered if you fire a shot at say 45 degrees elevation, does the bullet axial centerline follow the trajectory curve or does the thing land on its base tipped at 45 deg's? Years ago I read something discussing this as it pertained to artillery shells, questioning the idea that the shell nose tipped over at its peaked travel elevation height? Mortar shells have fins to keep the nose axial with its decent.
kw
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