First of all, define the need and you will most easily end up with the right product

The selection is large and the advertisements promise you everything, as long as you buy the right product. For me, it's about reading a lot about what I'm interested in and then making an assessment of which product I should try. Not infrequently, I then test shoot in wet newspaper to see if the bullet behaves as expected.
There are an incredible number of different types of bullet ammunition that are designed for different situations. There is seldom a universal sphere that does everything without the need should and must guide the choice. I start with a few different types of bullets, and what I use them for in my world.

Helmet

A pure training ball or a ball that is intended to either reach far into the game and preferably go through without expanding, ie not creating meat destruction. I use it on forest birds in situations where the strokes are short, then preferably a slightly blunt-nosed ball that releases a certain energy in the game but does not expand. I then think of my tree cellar caliber 22 horn as an example. A hole ball in a young bird does not have much left to eat if the ball hits from the "wrong angle", which is skewed from behind.

 
22 The horn with a ball suitable for tree cellar hunting. With its somewhat blunt shape, it releases some energy into the bird without destroying the meat. With this type of ball, it is suitable up to about 100 m.
  

Hole tip ball

A bullet that I use for forest birds when it starts to be top bird hunting. In my younger years, I used a standard silver torpedo, which is a pointed full-mantle bullet, I shot away a lot of birds that I did not find with that type of bullet. When I went over to Norma's diamondline or Lapua sceanar, both of which are hole points, the percentage of birds found definitely increased significantly. The bullets expand and trap the bird even after a not entirely perfect hit. My favorite top bird caliber is 6.5 * 55. It is a fairly flat-shooting and fairly wind-sensitive caliber with the right bullet (diamondline or scenes). Both when choosing a diamondline or the scenes ball, I have chosen the ammunition that is around 8 grams and 830 m / s. It is faster, but when hit by a bird at close range (20-40 m), the expansion can be a bit violent.
When choosing this bullet, I look at BC (ballistic coefficient) or briefly the bullet's flight and wind sensitivity. The higher the BC number, the less it is affected by air resistance and crosswinds. A ball with a high BC is often very streamlined and has a boattail (inward-angled rear part) which reduces the "suction" behind the ball. In order for it to emit energy in the bird, it is necessary that it is a hole tip, ie opens up and emits energy.

  

Lapua Scenar. 6.5 * 55. 8g v0 830 m / s. I have used both 7.8 g and 8 grams with good results on capercaillie and black grouse.

Blyspets, Obondad kula

When we come to what I am perhaps best known for (Bear hunting), my favorite is a bullet that opens quite quickly and leaves a lot of energy in the animal. Hence, I have opted out of bonded bullets. A brief summary of what a bonded ball is, the lead and the mantle are soldered together so that the ball when it expands holds the mantle and lead together. The result is a ball with very nice sponge and high residual weight. The problem with high residual weight for me is called breakthrough. If I have to shoot an attacking bear, I want the bullet to stay in the bear and not pass out behind it, because there is often one or more dogs. So my choice is an unbound bullet that does not have such a high residual weight but leaves off its power and possibly some lead fragments in the bear. The type of ball is often called a lead tip or vulcan, which in my world is about the same thing. The lead and the mantle do not sit together and sometimes split when hit inside the animal. The ball seldom looks as good as a bonded ditto but does the job well. On the other hand, there can be more meat destruction sometimes with this type of ball, especially if the direction is close and thereby the ball speed is high.
My experience is based on ammunition in the calibers 6.5 * 55. 9.3 * 62 and 8 * 57 JS.
Just 8 * 57 JS is a caliber I have used in recent years. The caliber is quite nice to shoot with, No fantastic ball track but is definitely useful up to 150 m without having to think too much about ball tracks. 6.5 * 55 is the caliber I started with as a bear hunter and would probably say that it is enough but is not optimal. A good hit is always a good hit, but when it comes to injured bears, sometimes a little more "stopping power" is needed.
9.3 * 62 is solid and good but gives quite a lot of beepblow (recoil) which can affect a quick second shot in the negative direction.
8 * 57 JS has for me become a good middle ground between shot effect and recoil. The bullet I used for a number of years and shot some bears with is Hornady's interlock. The bullet has done a good job of the bears I killed.

  

 

Hornady interlock, 8 * 57 JS. Test distance 80 m.
A bullet with an approximate residual weight of 65% after impact.

  

Lead tip, bonded bullet

A type of ball that I would use when hunting game. When the lead and the mantle are soldered together, the bullet emits very little of itself (high residual weight) in the animal's body. I tried farmed bullets during a season of bear hunting and was convinced that it was not for me. The bullet in most cases reached through the bears, which made me opt out of the type of ammunition, as I wrote earlier in the article, there is often one or more dogs behind the bear. And when it comes to bears, it is not always possible to choose your shooting opportunities.

Hornady interbond. 9.3 * 62. Test distance 80 m.
A typical image of a bonded bullet. Mantle and lead fit nicely together. The residual weight is usually about 90%.

  

Lead tip, Varmint (or slightly expanding bullets)

The type of ammunition is designed to usually have a high speed in order to expand quickly and release its energy in the animal when hit, and preferably not to have an impact. The ball type is rarely used on food game as the meat destruction can be substantial. On the other hand, in game where the meat is not used but the fur (for example fox or crow), the ammunition is well suited. Quite often, bullet calibers are used in 5.6 mm / caliber 22 or similar, but there are up to 308 w   in hornady's range of warm ammunition.

Lead-free bullets

In recent years, there have been lead-free alternatives. It's not something I've tried in real life. But the tests I did actually promise quite well. So the future will show if and when I switch to lead-free bullets. This is definitely something to consider now that the phasing out of lead in ammunition is imminent.

8 * 57 JS, Hornady GMX bullet. Test distance 80 m.

If you sum up a little, you can say that everyone is blessed in their faith. And faith can in some cases move mountains. But the laws of physics are not so easy to change.
As I tried to describe , it is a good idea to think about how the caliber and bullet should be used so you really get what you want from selected ammunition.
For example, if I were to use a very pointed full-mantle bullet in the 22nd horn for bird hunting, I would probably have judged the caliber to be quite useless, the frequency of birds that managed to get out of the shooting range had simply increased. If, on the other hand, I were to try long-range shooting with the mentioned caliber, my choice of blunt hunting bullet would result in a very low hit percentage due to the bullet's blunt shape (low BC), which makes it both wind-resistant and wind-sensitive. Although both of these parameters can be compensated and managed with very careful preparation as well as rangefinders and anemometers it's hardly easy to do alone.

  

So once again, define the need and act accordingly / Rasmus