Bryan Litz has new video series out

[Cgrutt]

First of new video series. New videos should be out weekly. If you're interested in ballistics check out his books at http://appliedballisticsllc.com/

[Pissed Off Patriot]

I've never heard of this guy, not that I'm involved in anything where I would have, but it raises an interesting question about bullets.

What kind of theory goes into the surface of the bullet?

For instance, my dad used to race sailboats and the surface of the hull was very important when it came to reducing the drag of the hull against the water. A very smooth glossy surface created more resistance in the water than a surface you would get from a wet-sanded paint because the water molecules could adhere to the rougher surface. Water molecules against water created less resistance than the hull surface did against water.

A similar concept is the dimples in a golf ball help the ball to travel further due to decreased drag.

Should I be wet sanding my bullets? lol

[Cgrutt]

I've got a few of his books he's been around a while. Believe retired military instructor but not certain.

[Cgrutt]

Part II out today Terminal Performance

[Meketrefe]

I've never heard of this guy, not that I'm involved in anything where I would have, but it raises an interesting question about bullets.

What kind of theory goes into the surface of the bullet?

For instance, my dad used to race sailboats and the surface of the hull was very important when it came to reducing the drag of the hull against the water. A very smooth glossy surface created more resistance in the water than a surface you would get from a wet-sanded paint because the water molecules could adhere to the rougher surface. Water molecules against water created less resistance than the hull surface did against water.

A similar concept is the dimples in a golf ball help the ball to travel further due to decreased drag.

Should I be wet sanding my bullets? lol

Finally something about firearms!! yeah!!!!

This guy is actually one of the innovators behind the hybrid profiles in long range bullets. Let me explain and perhaps answer your questions..

The bullet becomes more efficient in very slender shapes and with a boat tail in the end. Pretty much like the profile of sail boat actually. They even call it boat tail!!
So the overall shape resembles many things like plane surface sections, boat hulls and even animal profiles found in nature like a tuna that are great swimmers and
shapes that have to cut through water or air efficiently.

The surfaces of high end bullets are very clean copper jackets normally polished but specially they have to be very uniform in weight distribution and consistent.
Also one can get into what type of shape is in the slender tip before you get to the flat part or bearing surface. It is what is also called the Ogive that defines what kind
of shape more pointy and long or shorter and less pointy. Even round nose bullets have a shape. In long range bullets also called VLDs for Very Low Drag they
always talk about two profiles for that tip shape, one is a tangent o-give, the other is a secant ogive and now they have a hybrid that is a new thing the last 10 years.

The issue is how much of that tip is arched and were and how much is straight before the arch is defined again before the flat bearing surface. The tip is designed to cut
though the air, the bearing surface to engage the rifling and provide the rotation. There are mathematical models to define the efficiency and tip designs but also
one has to consider that the shape not only has to be efficient at cutting through the air (less resistance) but also at engaging a rifling in a bore.

Some of these VLDs with the secant design are good fliers but the flat shape in the tip is hard to engage with the riffing sometimes creating minor concentricity issues.
So these might be better to seat the bullets close the lands or even sticking to them to avoid these when the bullet jumps from the case into the rifling lands.
The tangent is more forgiving in self aligning and they can be great flyers too but they are not as good flying. So they came up with a new profile that makes
them a mix or both called hybrid. So these will have a bit of tangent after the bearing part and then enough secant to be very good fliers sometimes even better
than all secant ones. High end competitors try several options and then decide what type is best in terms of accuracy and performance.





The requirements to stabilize a bullet and therefore the rate of twist that is necessary is determined by a few important aspects.

- Length of the bullet
- Speed
- Design
- Weight distribution
- Type of rifling, etc...

A bullet weight might tell us something about the twist needed but we need to really pay attention to the length, shape, amount of bearing surface and initial speed
out of the barrel.

For example a solid copper bullet needs a faster twist for the same weight as a lead core bullet. It is a lot longer. It has to be, it is made of copper.
So better follow the initial bullets, ammo and firearms manufacturer recommendations.








Solid bullet section...





A solid copper bullet can make a bullet of the same weight be a lot more efficient w/o putting a lot more pressure/weight but
also bands are cut to reduce the amount of bearing surface.


This 200gr bullet can shoot flatter and further than the mighty 338 lapua magnum...




http://precisionrifleblog.com/2015/0...-line-bullets/

[WARFAB]

Are Hornady A-Max bullets second or hybrid?

[Meketrefe]

Are Hornady A-Max bullets second or hybrid?

"hybrid'ish" lol.

Initially jacketed hp with the polymer tip are also better and do not have the metplat issues.
sierra is also switching to the polymer tips thus increasing ballistic coeficients.
In fact if you look at where the popular 224 75gr and 308 155gr are today it was unthinkable
25 years ago.

[Meketrefe]

So tell me why the 7mm/08 will do better than the 260 reminton and even the 308 winchester parent itself for any role you want?

I want to see if you understand the essence and the value of the discussion here.

[Meketrefe]

Bump so I don't die. (The thread is saying that).

[Meketrefe]

Bullet porn...


I asked Barney Lawton, who makes Barrels and Rifles for the .375 Chey Tac of Lawton Rifle Barrels about Lost River Ballistics, apparently being off the Web why that is so. He answered, they had been bought and might pursue the Bullet business later again. He told me actually Warren Jensen promised him a Bullet for the .375 Chey Tac some Time ago, but did not deliver. Further he told me, Sierra should work on a jacketed Lead version too. I have not confirmed this with Sierra. Be my Guest to as to verify that by Yourself. I developed some comparable Bullets, see below:
Langstreckenflieger LM-101 | 8,5 mm MSG | LM-105 | 408-CT-MSG | 12,7 mm MSG



http://lutzmoeller.net/English/375-Chey-Tac.php

[Meketrefe]

I thought this was an interesting thread but nobody here seems interested.
This is the main problem from day one. For every 20 threads 1 is knowledge value content.

[Meketrefe]

....

[Cgrutt]

Good explanation of MOA and MIL...

[Meketrefe]

two different units of measure for the same thing. Mil is a lot easier. Military standard.

Anyway here is what I have in mind for the 30 caliber cat a tad shorter than the dakota and for regular mangum bolt head/face.
The rum will be a great donor for the cat. This will be an interesting wildcat. I want to see if I can make it close to 2000 yards supersonic..

[Jimbo_79]

Mek, your knowledge astounds me and your 30 cal design has me very interested! I read a bit in the Wildcat thread. I wanted to comment but it was all over my head.