This is Part 2 of this topic delves deeper into cartridge choice. If you haven't read Part 1, you can do so here There will also be a Part 3 which covers affordable rifle choices and a Part 1 which covers everything in less detail. This post goes deeper into the "why" of cartridge choice.
The goal for a new hunter who is a small person is to enable them to be capable. You want them to be able to build skills quickly and be comfortable and capable with a tool that will do an ethical job of taking an animal. We want to choose a cartridge that offers a safety buffer for terminal effectiveness and balance that against excessive recoil. If a small person feels physically assaulted by recoil they aren't going to be able to build marksmanship skills. On the flip side, if the cartridge selected isn't powerful enough to swiftly kill the hunted animal, you can end up with a wounded deer that needs to be tracked to be located, or perhaps is never found and dies hours or days later. Both of those can easily turn off a youth or new hunter from the idea of harvesting their own meat. So we want the experience to be pleasant and we want the cartridge to be effective.
One way to do that is to use lower recoil ammunition for practice and use more powerful ammunition for the hunt. Most people don't feel recoil in the moment of the hunt, so as long as the recoil is at a safe level for the hunter, it's going to be fine. In my cartridge selection below I list some commercially available reduced recoil loads where they are available. As well, if you reload (aka hand load) or know someone who does, Hodgdon offers a gun powder specifically meant for loading light loads, Trail Boss. These end up being about half power. They also offer information to load more powerful, but still lower recoiling, loads using H4895. The guide for loading reduced recoil loads can be found here. I've used both methods with great results.
First I want to discuss the basics of recoil. A 90lb person is going to experience twice the felt recoil of a 180lb person. Recoil is just a math equation. Halve the weight behind the rifle and the force doubles. Something that has very little felt recoil for me has very real felt recoil to a smaller person. But that is just one part of the problem. Being small often presents three primary issues. You weigh less, you have less strength and you have shorter arms.
Holding a rifle is an odd use of stregth and short arms compound it, because they only reach so far. Longer rifles put a lot more of the weight on your support hand, which is extended, instead of your grip hand which is closer in. This is exacerbated by having shorter arms. Somone 5'10" may find a 7 lb rifle with a 22" barrel and a 13.5" length of pull (the distance from the rear of the stock to the trigger) holds very nicely, as the center of balance which is also the center of weight, sits between your grip hand and your support hand. That same rifle held by someone 4'10" puts the center of balance closer to, or even at their support hand. That makes it lot harder to hold steady. They have to hold more of the weight with their outstretched arm and that can make their stance and aim quite wobbly.
Knowing this, the obvious choice is to choose a shorter barrel and a shorter stock, which moves the center of balance closer to the shooter's body. That comes with three caveats. First- if you cut 6" off a barrel and an inch or two off the stock and you reduce the weight a bit, which increases the recoil. Second- reducing barrel length decreases velocity for a given cartridge which can affect it's terminal effectiveness and trajectory. This can be managed by choosing an efficient cartridge for a barrel length. Lastly- a shorter barrel offers more muzzle blast than a longer barrel. This is because high powered rifle cartridges fired from a short barrel often don't have enough dwell time, barrel length or barrel volume to burn all the powder. When the bullet leaves the barrel the remaining powder combusts when it reaches oxygen and can create quite the fireball and noise. At dawn or dusk this is really visible and can be disconcerting. The Mosin Nagant carbines are known for this behavior, as they shoot a 30-06 power cartridge (7.62x54R) in a 20" barrel. So we have to balance the cartridge with the barrel length.
If we consider 243 Winchester against 308 Winchester, we can see that for each inch of barrel the 308 has 31% more volume. So for a given powder load, we would need a 31% longer barrel to achieve a full burn. A 44 magnum barrel has a volume that is 76% larger than 243. (44 magnum actually uses a bullet that is .429" in diameter) Now, these numbers aren't exact, as different powders have different burn rates and produce different volumes of gas, but you get a general picture. Figuring out the exact rates would take a lot more math than I am capable of doing in a post like this. The bigger the bullet diameter, the more space we have for gasses created by powder combustion.
We can now consider cartridge choice. If you have a small hunter and want to select a rifle that fits them well, you want to make sure you select a cartridge that suits the barrel length. This gets into the concept of "overbore" cartridges, which I won't get into much here, but you can get the gist of it in this article. Consider the ratio of powder to the volume of the barrel. The barrel volume is a simple math equation- bore (bullet diameter) times length. There has to be enough space inside the barrel for the powder to burn or it will create a blast outside of the barrel. The more overbore a cartridge is, the longer barrel it needs to be in it's efficiency range.
For instance, a 22 long rifle cartridges burns up all it's powder in 12 - 14" of barrel. A 9mm does so in about 14" as well. A 357 or 44 magnum takes 16" to 18" of barrel to fully burn the powder. A high power rifle round could require a longer barrel than is practical to burn all the powder, so some muzzle blast is innevitable. An intermediate power rifle round, like 7.62x39, may approach the velocity of higher powered rounds in short barrels, simply because the 7.62x39 is turning all it's available powder into acceleration while a 308 may only be using 75%. So in short barrels intermediate power rounds are likely a better choice than high power rounds. A high power round will offer more recoil and more blast for very little extra performance. Let me state that again, since it is the crux of the discussion.
A high power round in a short barrel will offer more recoil and more blast for little extra performance.
For a cartridge like 308, you can estimate you will lose 25 fps per inch of barrel from 26" down to 18". This is backed up by lots of tests by people, including my own. I have 2 Steyr rifles chambered in 308, one has a 24" barrel and one a 20". I have chronographed several different loads from each and the average velocity difference between the two is right at 100 fps average. However, the heavier bullets that move slower are less affected than lighter bullets moving faster. Heavier bullets take up space inside the case, space that can't then be used for extra powder. My average for 150gr bullets is only 84 fps loss. My results for a 130gr bullet is 130 fps lost in the shorter barrel. That's a fair bit of difference.
Reduce the bullet diameter and/or weight and the shorter barrels have a greater effect. I tested 3 6.5 Creedmoor rounds in two Ruger rifles- one with a 26" barrel and one with a 20". The average velocity over 15 shots with 3 different loads was more profound- that 6" barrel reduction lost 232 fps, or an average of 39 fps per inch of barrel. The 6.5 Creedmoor has a bullet takes up 73% of the frontal area of a 308 but uses 84% of the powder charge, so it requires a longer barrel to get the most from that. Fat cases with a lot of capacity that shoot skinny bullets require longer barrels to be efficient.
We can look to 243 as an example of this- since it is based on the 308 case, has a smaller bullet and has more powder capacity than 6.5 Creedmoor. According to this test 243 is loosing 41 fps per barrel inch lost. That ads up a lot faster than 25 fps loss you get in the 308. For lighter (80gr) bullets it was pretty consistent over the range, but the heavier (100gr) bullets the velocity loss accellerated when the barrel dropped below 20".
I don't have a 16" barrel 308, but using rough estimates, my 130gr load would have a velocity of 2690 fps in a 16" barrel. Meanwhile, in a 7.62x39 rifle with a 16" barrel I get an average velocity of 2463 fps with a 125gr bullet. I get 91% of the velocity with only 63% of the powder and recoil in the 7.62x39 vs the 308 in that short 16" barrel. The less powerful cartridge is better suited to that barrel length. It is more efficient in a 16" barrel than a 308. A 7.62x39 can achieve the velocity listed on the ammuntion box in a 16" barrel, where a 308 fired from a 16" barrel is going to be 200 fps slower than the velocity advertised by the manufacturer, because they typically use 24" barrels for testing. So the performance advantage you get in a 308 over a 7.62x39 or 30-30, which use less powder, is greatly reduced as barrels get shorter.
So as mentioned, cartridges that have a larger case (i.e. powder capacity) in relation to the bullet weight and diameter need a longer barrel to be efficient. The cartridge type most likely to burn their entire charge in barrels as short as 16" are straight walled cartridges. The case diameter is the same size, or very similar to, the bullet diameter, so the powder charge to bullet wieght ratio is a lot lower than a bottlenecked case. In cartrdiges like this, longer barrels can actually reduce velocity. A 357 isn't going any faster in a 18" barrel than a 16" barrel for nearly all ammunition choices. A 9mm shot from a 20" barrel is likely to be slower than one shot from a 14" barrel. The poweder burned up at 14" and is no longer accelerating the bullet, so the only force acting on the bullet is the drag of the barrel.
So that's a lot of words and numbers to state the point, but I wanted to include it for those who may be interested. This link shows some data on a few cartridges, including 6.5 Creedmoor:
Knowing that, here are some velocity and energy numbers on some suitable cartridges. Energy isn't the only indicator of terminal effectiveness, of course, but can be considered as a data point. The diameter of the bullet certainly matters as well, as larger diamter bullets leave bigger holes. Energy combined with bullet weight can help compare recoil. Notice all the reduced recoil loads use lighter bullets than the traditional full power hunting loads.
Ammo examples are Hornady American Whitetail ammo when it was available. Lite recoil examples is Hornady Lite or Remington Managed Recoil ammo. I'm not endorsing either one neccessarily, they just have good data on many common calibers.
High Power Rifle Cartridges
308 Winchester - The commercial version of 7.62x51 NATO and very common
7mm-08 - 308 necked down to 7mm (28 caliber) from 7.62mm. Pretty common but falling out of favor with the rise of 6.5 Creedmoor.
6.5 Creedmoor - a 308 case with a shorter body and longer neck set to 26 caliber. It has less powder capacity than the other cartridges here as a tradeoff to allow for longer bullets and has become quite popular in recent years.
243 Winchester - a 308 case necked down to 24 caliber (6mm). Very common and a capable performer.
30-06 - a cartridge that has been around for a century and used by US forces in World War I and II. Not recommended for this purpose but listed for reference.
270 Winchester - a 30-06 case necked down to 27 caliber. A very popular and capable cartridge.
25-06 Remington - a 30-06 case necked down to 25 caliber. Not as common as 243 Winchester, but more powerful with reasonable recoil.
30-30 - a less powerful 30 caliber cartridge than others on this list that has taken more deer than any other in the US.
|Cartridge||Ammo Type||Bullet Weight||Velocity||Energy|
|308 Winchester||Full Power||150||2820||2648|
|308 Winchester||Light Load||125||2675||1986|
|6.5 Creedmoor||Full Power||129||2820||2278|
|243 WInchester||Full Power||100||2960||1945|
|243 Winchester||Light Load||87||2800||1514|
|270 Winchester||Full Power||130||3060||2703|
|270 Winchester||Light Load||120||2675||1906|
Next we can consider Intermediate Power Cartridges. In general there are not any commercially available light loads available for this class of cartridges, although a person can still make their own.
7.62x39 (30 caliber) - a 30 caliber Russian round that is exceptionally common and affordable
6.8 SPC (27 caliber) - a cartridge designed for the AR-15, uses a larger case and bullet than 223
6.5 Grendel (26 caliber) - another cartridge designed for the AR-15, uses a larger case and bullet than 223
|Cartridge||Ammo Type||Bullet Weight||Velocity||Energy|
|6.8 SPC||Full Power||110||2550||1588|
|6.5 Grendel||Full Power||123||2580||1818|
Lastly we look to Magnum Pistol Rounds - Notice these all have less velocity and energy, but make up for it with larger diameter bullets to achieve good terminal results.
|Ammo Type||Bullet Weight||Velocity||Energy|
|38 Special||Light Load||125||1210||406|
|357 Magnum||Full Power||158||1415||702|
|44 Special||Light Load||165||1330||648|
|44 Magnum||Full Power||225||1410||993|
|45 Colt||Light Load||255||1122||648|
|45 Colt||Full Power||225||1500||1124|
Here are some of the above graphed out to show approximated felt recoil. I calculated the magnum pistol rounds using a 5 lb rifle and the high power rifle rounds at 7lbs, fyi.
The above chart came from the Shooters Calculator Website.
You may notice I left off some popular cartridges, and there are a few I would avoid. 300 Blackout just doesn't match the power of other 30 caliber cartridges here so I left it off, it falls short of the 7.62x39. 350 Legend is the hot new deer cartrdige but I left it off because it's too new and nobody knows if it will be around in a few years. The history books are full of cartridges that were introduced and didn't catch on, leaving anyone who owns a rifle having to look hard to find ammo. While 223 / 5.56 has been used to take lots of deer, it just isn't ideally suited. It's primary wounding mechanism is by fragmentation, which just makes a mess of the meat. Since the primary point of deer hunting is to provide food, choosing a round that spreads tiny fragments of lead and brass throughout the muscle is a bad idea. You can get bonded and copper bullets for the 223, but the wound channel just ends up being smaller than the next smallest cartridge listed. It is going to make a smaller wound channel, so it descreses the chance of hitting vital organs. I shoot a lot of 223 myself, but there are many better choices for deer hunting, even if you want to use the AR-15 platform. 223 with non-fragmenting bullets just doesn't offer the extra terminal performance or wound channel to drop a deer cleaning with a shot that isn't perfect. Save it's use for people who are experienced marksmen.
There are lots of great choices here! Hopefully this will help you narrow down your choices. There are of course other options, but each have some downsides. 260 Remington and 257 Roberts are great choices, but both the rifles and the ammo are hard to find today. The same goes for 35 Remington, which is a 30-30 necked up to take 35 caliber bullets and a solid choice, but only one company today makes a rifle chambered for it, and the ammo is going to keep getting harder to find. If there is a cartridge you think I overlooked, please let me know in the comments and I will happily consider it.
Good luck out there!