Depending on what caliber you shoot, you may have a plethora of bullets to choose from. Just look at .308. You can choose from 110 up to 200+ grain bullets from multiple manufacturers and multiple types of bullets. E.g. Target, hunting, OTM, lead, brass, copper coated ect. So, how do you choose? We will talk about hunting bullets, but we're going to focus mainly on bullets for long range shooting. I want to be clear up front, I am not a hunter but, per the manufacturer, bullets intended for long range shooting are not good for hunting. As a hunter, you are responsible and owe the animal a quick and clean death. If you are hunting at medium or long ranges, you need to be very aware of your skill set and be 100% sure that you can make the hit.
Before looking at bullets, I look at the rifle first. More specifically, the barrel's twist rate. This will tell me what grain (more accurately length) of bullets to look at. This is a very good starting place.
So how do you know the twist rate of your rifle? Well, it should say on the side of the barrel. It will say 1 - 10 or 1 - 8. What this means is that for every 10 inches of your barrel, your bullet will twist one time (or every 8 inches the bullet will twist once). The lower the number, the faster the twist rate. This means you can stabilize heavier and longer bullets versus slower twist rate like 1 - 12 for lighter or shorter bullets. In my experience, a slightly heaver and longer bullet is almost always better, and where I start when looking for bullets. If the twist rate is not on the rifle, check the manufacturer website. If all else fails, you can use a cleaning rod with a brush or a patch that fits tight. Mark the top of your rod or use tape to mark it. Push the rod in slowly and, once it makes a full revolution, mark that spot. Then measure between your two marks, and that is your twist rate.
Now that I know my .308 has an 11.25 twist rate, what do I do? Well, I'll look at popular factory ammunition to get an idea of what to look for. For factory ammo, I like Federal Gold Medal Match. FGGM comes in 168 Sierra Match King and 175 Sierra Match king. Federal also makes Federal Gold Medal Berger 185. Hornady match comes in 168 ELD and 178 ELD. So, now that I have a good selection of bullets to check out, I'm going to do two things, find the maximum effective range (this can change due to environmental factors such as barometric pressure and altitude) and the bullet's gyroscopic stability factor. First, lets start with the maximum effective range. To keep everything as even and comparable as possible, I'll say my maximum effective range will be the distance that the bullet hits 1300 fps. This is just above transsonic or mach 1.2. I am going to use the data on the ammo box to give me a general idea of what I can expect from this round and enter it into a ballistic calculator. Next, I'll use a Miller Stability Factor calculator to determine the gyroscopic stability factor of each bullet. Ideally, you want your gyroscopic stability factor to be between 1.4 and 2. At 1.4 a faster twist rate or lighter bullet is recommended. At 2.0, a slower or heavier bullet is recommended. Closer to 1.4 is recommended for extreme long range shooting. Lets see how that looks. Keep in mind, this is for my rifle and in my environment.
168 SMK
Bullet Length - 1.125
B.C - .462 G1
FPS - 2650
Maximum Range - 825 yards
GSF - 2.34
175 SMK
Bullet Length - 1.24
B.C. - 505 G1
FPS - 2600
Maximum Range - 874 yards
GSF - 1.83
185 Berger
Bullet Length - 1.344
B.C. - .560 G1
Fps - 2600
Maximum Range - 970 yards
GSF - 1.55
168 Eld match
Bullet length - 1.273
FPS - 2700
B.C. .523 G1
Maximum Range - 962 yards
GSF - 1.65
178 Eld Match
Bullet Length - 2600
FPS - 2600
B.C. - .547 G1
Maximum Range - 948 yards
GSF - 1.55
Let's also add two more bullets that I tried. It didn't work out too well, so let's see why. These bullets are very similar. The biggest difference is bullet length. But look how the length increases the B.C. and drops the GSF well below 1.4.
208 A - Max Hornady
Bullet length - 1.488
FPS 2550
B.C. - .648 G1
Maximum Range - 1052 yards
GSF - 1.27
208 Eld match
Bullet Length - 1.535
FPS - 2500
B.C. - .670 G1
Maximum Range - 1088 yards
GSF - 1.16
Now that I have gathered this information, I can start to look at what I need/want in a bullet. I want as close to 1.4 as I can get when it comes to the G.S.F, but I also want the best maximum range and B.C. The 3 best look like the Berger 185, the Hornady 178 and the Hornady 208 A-Max. So, I would buy a box of each and test them out to see how they work. I would log all the data that I could. First and foremost, I am looking for accuracy, consistency and the smallest groups. Well, I did just that with every bullet listed here. And believe it or not, I went with 175 SMK. I picked the 175 for a few reasons.
Reputation: the SMK have a wonderful reputation and were recommend to me by a person directly responsible for teaching me long range shooting.
M24 Sniper Rifle: My M700 5R is loosely based off of an M24 sniper rifle. Both guns have an 11.25 twist rate and 5R rifling, and the military uses 175 bthp.
Ogive: The Ogive on the SMK are tangent. Tangent Ogives are not sensitive to seating depth when reloading, so that just gives me one less thing to worry about.
They just work. I bought a few boxes of Federal Gold Medal Match 175 SMK and my rifle shot them very well. On average, I was shooting .45 MOA at 100 yards. I can mimic factory ammo with my reloaded ammo, so I can have the same bullet drop. Also, this ammo is readily available, so if I don't have any reloaded ammo I can just pick up a few boxes of FGGM 175 and be good to go.
There is one bullet that seems promising on paper; however during testing, it was somewhat disappointing: The 208 A - Max by Hornady. Once we look at the G.S.F, the test results are understandable. This bullet doesn't come in factory loaded ammunition for .308; I had to reload for it. And reload I did. A LOT! Everything looked so good on paper. It hit harder, it was heaver and it reached out further. But look at the GSF: 1.27. I just couldn't get under 1 inch at 100 yards. I tried many different powders, primers, and seating depths. But thats ok, I have the 175 SMK and they work amazing.
Heavy vs. Light
As you can see in the data, the heavier bullets did better. And by better, I mean maximum distance. Even at 200 fps slower, the 208 A - Max has a much higher B.C. This helps the bullet to cut through the air and retain its energy much better, which allows it to reach out further than a faster, smaller bullet. I have seen so many people look for, and go after faster bullets thinking the faster the better. When in reality, a bigger and longer bullet almost always wins. But there is a tipping point where the bullet is too heavy, as we see with the 208 A-max in an 11.25 twist rate. Of course, there is a trade off. A slower bullet will have more drop, so you will have to dial up more. If I look at all the information that I collected, the 175 really is the least of what I'm looking for. But, because I reload my ammo, I know I can get better performance. I also don't know the environmental conditions or the rifles that they used to test the bullets. I am only using what's on the box as general information. And again, top priority was accuracy and consistency. It just so happens that the 175 FGGM and my reloaded ammo worked really well for me. And my local gun store always has FGGM 175 in stock. So, I always have access to this bullet and ammo.
Ballistic Coefficient
In ballistics, the ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration: a high number indicates a low negative acceleration the drag on the body is small in proportion to its mass. So we are looking for a bullet with a high ballistic coefficient. The B.C. should be written on the side of the box but, if not, you can check the manufacturer's website.
Speed vs accuracy
A lot of people think the faster the bullet the better. This is not entirely true. A faster bullet with a lower B.C. may not give us the results we are looking for. If in your research, you are not seeing the results you want, you might want to look at a different caliber altogether. Our number one goal is accuracy. Hitting a target at long range with one shot. This goal is reached through consistency or match grade ammo. Through load development, you will want to pick the most consistently accurate round, not the fastest. If you're lucky, they will be one in the same. Keep in mind your ammo vailability as well. It would be a huge let down if you go through the load development process and gather ballistic tables, then realize that you can no longer get that bullet or ammunition. Put in the work. Write everything down, but ultimately your rifle will tell you what bullet to pick.
Hunting Bullets
With hunting bullets, supreme accuracy may not be your number one goal; it may be reliable expansion. If the vital area on deer are roughly 10", then you don't necessarily need the utmost accuracy. I have been told by several people they haven't shot a deer past more than 200 yards. If the goal is to hit within 10 inches, then at 200 yards thats 5 MOA. That's more than enough room for error. I aim for .5 MOA when dialing in my load during load development. But, 1 MOA should suffice with a hunting bullet. This doesn't mean it's ok to load a sloppy round. I just mean, you don't need a hunting round capable of shooting half MOA at a 1000 yards if you are not shooting past 200 yards. While shot placement is everything, you are going to want a bullet specifically designed for hunting applications. You need to be 100% sure of your skill set and know what your maximum distance is to kill an animal with one shot. You also want to make sure your bullet will expand properly at that distance as well. Using myself as an example, when I get to the range, I start shooting at 500 yards. 99% of the time, I hit a 4-inch target with a first round hit. I am confident that I could easily make that shot and it be an ethical kill. While I'm pretty sure I can do the same at 600 or 700, I would not test this on a living, breathing animal. Hunting is not the time to test your limits or capabilities. Save that for the range.
The Overwatch
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