School us on bullet tipping.

[Rinso]

Trev & macca,

Yeah a great boat macca 5 metres 90 Suzuki goes real well and easy to get in and out on your own.

Trev mate would be great to catch up. Are you still punching above your weight or has Kerrie thrown you out ?

I reckon I will scratch that itch one day but just now we are coming into summer so Black Marlin, Lontail Tuna and other fun things will turn up around here like Giant & Golden Trevally add Coral Trout and Red Emperor to name a few add Mud Crabs and Prawns will be around so maybe a little bit yet.

I would probably look at a 1k match at Narromine because I don't think Dave Goodridge would ever forgive me if I didn't attend his shoot.

The question now is do I build another 260AI or go with something else and if so what?

[trevort]

still punching above my weight. Taking her to US in Nov and we have a date in an Elvis chapel to renew our vows after 10 years!

You could use my rifle in Narromine next year as long as we are on different details

[jacko-2]

ok ,my take on poimting, it takes out a lot of the verticial due to i think that you have sorted them into groups.
They print oprox 1moa higher on average,,best results when u point turn them and repoint,, the hoover iz best but so iz the whidden with a few mods,,vlds showed the least gain hight but the biggest verticial tightening,,go figure,,
i dont trim anymore, just sort and point,, and if you think they are better then you mite shoot better,,the other option iz to use hornady elds , end of pointing problem, cheers

[Tony Z]

Jacko i have 180 ELDs coming but only a 100 as i predict the usual. I have 162s from the 284 experiment where they measured good but shot like crap. Good for steel plate or pigs. Not since the Amax 162 #326 lot have i seen a Hornady worth owning.
I did meplat cut and insert tips a few years ago with zero gain in accuracy. A lot of effort for no result. The tipped SMKs are a joke for what we do so its no surprise that the rest of the line is yet to see a tipped version. Hornady reckons the tips melt. Others reckon the tips come loose during spin up. Either way no one uses them in competition and does well these days.

[Tony Z]

Jacko i will add that the smallest day agg at Townsville was shot with Hornady 162 Amaxes at 5.3xx". Woollie did it with the 7 Redneck but with an 11 twist Dennis did for me. I was convinced the 162s were spun way too fast and tips were coming loose so i got that barrel to suck it and see. I still maintain that is the issue and may be why you had ordinary results with the ELD Ms.
As for BC loss on the slow twist barrel. Well i watched every shot Woollie fired and saw each trail. In that wind on that day they went in the center. It reminds me of what dg said at Narromine. At some RPM ranges bullets become "stable" and that is where they shoot well.

[dg]

off topic admittedly, but as an analogy and for food for thought, has anyone ever thought about why well made and high quality free spinning tops or gyroscopic bodies behave as they do.

above a certain rpm, everything appears hunky dory with the object spinning and appearing to be very stable about it's axis.

BUT after a period of time in which the object's rate of spin decreases, it's rate of revolutions decrease to the point where it becomes unstable, gets an ever increasing wobble and then finally falls onto the surface on which it has been spinning before coming to rest.

obviously friction from the point of contact with the surface on which it spins and from the surrounding air are responsible for the decrease in angular velocity.

but why does it fall over and could this have any relationship to ballistic motion ?

cheers
dave

[jacko-2]

tony ,,ive had the most consistant groups ,,i mean groups , not one of,, with 9 twist using elds,, the elds r more consistant than the amax,, ive just got one barrel that loves amax,, but the berger 180 vld chew them u when the wind gets up,, im going 1-8 twist because i like what i see on the target in varing winds ,,want to talk records,,!
cheers tony,,

[dg]

off topic again

SORRY

According to accepted theory (and remember a theory is a yet to be proven or shown fact) for a regular shaped rotating body to achieve PERFECT balance it must share a common centre of mass and centroidal axis.

It also should possess homogeneous longitudinal and cross sectional material density distribution.

However despite the tremendous and ever improving standards in material preparation, manufacturing and measuring technology and techniques, I reckon it is fair to say that this level of required Balance Perfection does not exist.

To elaborate further, the last time I checked, every manufactured item is made to a tolerance.

These tolerances (however small) allow for the fact, that items cannot be made to a definite weight, length, width (or roundness) or straightness etc.

Well, what all this nonsense got to do with precision shooting and the ongoing efforts by many to shoot the smallest possible groups.

Despite the most modern barrel manufacturing techniques employed today, most agree and recognize that barrels are not straight which is easily seen and measured. (and, let’s not get into the effects of inconsistent steel production quality, heat treating and the like)

However to take this further, just how round are barrel interiors and are all lands and groves identical in width and height etc ?

Step back a procedure or so and apply the same size and shape standards to lathes, reamers, drills, grinders, deltronic pins etc etc all are made to extremely high standards but the tolerances still apply to allow for any variations in their physical dimensions.

Projectile wise, yep, some measure, weigh better and shoot more accurately than others, but when it comes to roundness?? and interior integrity??, we are at the mercy of the manufacturers and designers.

So after, some of us spend hours sorting projectiles, we then load and send them via an interference fit through a “round “barrel in which they are subject to mind blowing forces of linear and rotational acceleration, and not to forget that at the same time, the lands, grooves and slightly smaller barrel diameter have changed the physical dimensions of the projectiles and possibly the interior integrity.

At the same time, have these dimensional (and interior changes??) possibly also altered for better or worse ?? the BALANCE DYNAMICS of the projectile???

According to the experts,” a spinning top is stable because it is attempting to rotate about the singular principle axis” and it wobbles sometimes due to “procession” as the angular momentum changes.

And are not these tops subject to same size, shape, material, manufacturing variations, tolerances and out of balance factors mentioned previously?

If we accept that projectiles have even the slightest variation between the centroidal and centre of mass axis, then would it also be feasible to accept that they may behave like a spinning top (or similar gyroscopic body)?

Could it be, that as per a top, spinning tyre etc that the overall dynamic balance of a projectile could experience variations as the rate of spin is increased or decreased?

Nowadays, many refer to ladder tests and barrel vibration induced nodal points when tuning, as the velocities are increased or decreased.

Could it also be a consideration, that any change in the dynamic balance of projectiles has a significant effect or influence on projectile flight characteristics, stability and inherent accuracy as velocities are also changed ?

Are too many questions, not enough facts!!!!

cheers
dave

[Tony Z]

It has been a while but i have made a couple of die bodies, some sleeves and various tipping inserts and here is where I'm at.
These are junker 175 SMKs i am playing with and about the bluntest bullet i think i will ever fuck with. I intend to shoot modified tipped bullets at the next 600 match once again in the test dummy 308 HG to nut out any further bugs.
So here's what i have seen so far.
I looked at how the Hoover and Whidden units work and tried to come up with a better option for both alignment and tip profile. There is absolutely nothing on the web about the Pindell unit that is basically a small lathe that cuts the tip profile rather than swaging it. There is also a very interesting tri roller type pointing gadget that looks intesting. Either way I have great reservation that simple base to ogive measurement is the way to go here and i will explain why.
So what i did with my ogive gauge that i had built years ago was to simply invert the 30 caliber ogive sleeve so the bullet comes in from the bottom. The bullet then slips into the sleeve coming to a dead stop with point up, then the micrometer reads off the length variation on meplat position. In other words the distance from ogive data line to meplat is measured. There was absolutely no correlation to this measurement and base to ogive. When i thought about it it is exactly the way my meplat cutter measures and cuts where some bullets get heaps cut off and others barely touch. So it was a no brainer that this was the measurement that mattered because if the profile of any bullet swaging die is done with the same cherry, this profile is most likely the one to be more uniform. Especially if it is a custom maker with one point up die each bullet passes through. So a length variation here is a difference of diameter through the conical cross section up or down the die. A tipping die cannot ever rectify this error. Only batching can minimize it. The Whidden type die is exactly what i do not want then. But i made one anyway just to test the theory.

So by tipping from base to ogive measurement with my Hoover style die gave inconsistent meplat diameters. Smaller meplat as seen in the pic below, but very clearly inconsistent when compared to others.
By ogive to meplat measurement batching my second die gave near identical appearing meplat diameters that i was able to varify through use of a borrowed optical micrometer.
So to me so far it says a few things, yet to be tested but certainly feasable. If you randomly select and tip a bullet using either die they will no doubt increase that particular bullets BC somewhat. Again, yet to be confirmed. Select randomly and tip by Hoover style die will increase BC but not decrease BC SD. Again not tested but i can physically see and measure the variation. I cannot see by my bullet measurement how it could be possible except with the very best batch lots of perfect bullets. They do exist but are rare.
When i meplat cut bullets by base to ogive measurement as opposed to ogive to meplat measurement selection, once again the latter showed more meplat diameter uniformity when they were tipped with my other die.

This brings me to a test Henry Childs did when the Whidden( not stated by him but by reckoning it had to be) die first appeared. He shot a hundred each of 155 SMKs through his radar setup. A hundred tipped and a hundred meplat cut. Previous testing had shown 7 to 9 % BC variation on untouched bullets. Meplat cutting alone indeed decreased BC but most importantly reduced spread to 2 to 3%. Tipped bullets showed an increase in BC but maintained the same 7 to 9 % spread. Good but not good.


The Hoover style tipping die is simple and quick and fits any 7/8s press. The way i did it for ogive to meplat tipping was a bit more complicated and was best done in an inline type die and arbor press, at this time where i hopefully get one to the stage it needs no press at all. Importantly I can physically measure the difference which to me means a possible gain in BC and a reduction in BC spread. Hopefully
Below is a pic of two 175 SMKs where one is tipped in such a way that the tangent flow is unbroken. The other is an untouched bullet tip.
Both die types use shared sleeves and tipping inserts. Not a fanboi of the little cone i see on tipped bullets.
Another variation i wish to trial is the Montour style meplat cutting and hollow point reaming tools that can help to further reduce the meplat diameter after tipping. One custom bullet manufacturer is able to get meplats down to five thou diameter with similar tools. Probably not advisable but seems possible.