Stillwater Armory
Guns, Gear, & Training

A Guide to Caliber and Ammunition Selection for Concealed Carry

Caliber And Ammunition Selection

For true defense with a firearm, putting rifles and shotguns aside, you should carry the largest caliber handgun you can shoot well with as high a capacity as possible.  For comfort while carrying concealed, you would carry the smallest firearm you could possibly find.  Carrying concealed in the real world lies in a compromise between those two extremes.  This article does not concern itself with which firearm you should carry.  As long as you choose a well-proven model that you can shoot well and can reasonably be concealed and carried all day, every day with a degree of comfort, you will not make a bad choice.  Nor will we concern ourselves with tactics.  Shot placement and the ability to deliver devastating and overwhelming fire in your defense will be up to you to obtain through training and practice.  With that said, let’s look at what caliber you should consider and what type of ammunition you should carry.

First, it will be important to understand some common terms and vocabulary.   Ammunition is generally divided into several different categories, each with its own purpose.



“Ball” is a round-nosed, metal-jacketed bullet. Often referred to as full metal jacket, or FMJ, ball ammunition is rarely the best choice for a defensive round. FMJ ammo does not expand but will deform if it impacts an obstacle such as a wall or engine block. Ball ammo generally feeds and cycles very well in semi-auto and automatic firearms. It also is the king of penetration. The military used FMJ in all it’s handguns and rifles specifically for the reliability and penetration characteristics. The Geneva Convention governs the use of ball ammo by the world’s militaries. Fortunately, you are not limited by these standards and should choose other types of ammo for carry and relegate FMJ to the practice range. It is perfectly acceptable for training and practice and is generally lower in cost than other types of ammunition.


“Hollow Points” or HP or JHP (jacketed hollow point) have a hollow cavity in the nose and usually expand (and stop) in the body of the attacker. This transfers all the kinetic energy of the round into the target for maximum stopping power as opposed to FMJ, which can penetrate a target fully and exit the attacker, therefore transferring less energy. Hollow points are almost always the best defensive round as they offer the best chance for stopping the attack and the lowest chance of the bullet exiting the attacker and hitting an innocent bystander.


“Soft Points” or SP or JSP (jacketed soft points) are metal-jacketed bullets that leave an exposed tip of lead at the nose of the bullet. These do not make good defensive rounds in handguns as they offer limited expansion and the chance for over-penetration. 


“Wad Cutters” and “Semi Wad Cutters” are reserved for revolvers. These are generally conical shaped lead bullets with little or no jacketing. Unless fired from a high power revolver such as a .357 magnum, these are not very good defensive rounds.


"Round Nose Lead” or RNL is a rounded bullet with no jacketing. Also called lead, round nose. These are worthless as a defensive round. They are only acceptable for practice but be prepared to spend considerable time scrubbing the lead out of your barrel. In general, I would avoid this type of ammunition.

Other terms you are likely to hear in selecting your ammunition include:

+P           A round that is loaded to higher-pressure level therefore developing higher energy characteristics.  Basically a “turbo-charged” round.  Make sure your firearm is approved for +P ammunition or you could have a catastrophic and dangerous failure.

+P+         Loaded to even higher standards than the +P round.  Very few guns are rated for +P+ ammo.


A note about terminology.  One of the quickest ways to identify yourself as mis-informed is to call the magazine of an auto-loading pistol a “clip”.  While clip and magazine are often used interchangeably, they are different.

A clip is a device that holds ammunition together to facilitate loading a rifle such as the M1 Garand.  The ammunition is not completely encapsulated nor is the ammo fed towards the chamber via an integrated spring.

A magazine completely encapsulates the ammunition.  The ammo is presented for loading into the chamber via a spring located in the bottom section of the magazine.  Virtually all self-loading pistols use a magazine.


Easily, the most important characteristic for you self-defense ammunition is that it function properly in YOUR gun.  Hollow-point ammunition is generally the best choice but it is also the most expensive choice.  You must spend some time firing your hollow point ammo to confirm functionality, accuracy and performance.  I make it a habit of firing a magazine or two of my defensive ammo every month just to build confidence in the ammo but also to ensure I always am carrying “fresh” ammunition.

You should also only carry premium, factory ammo. Do not buy reloaded or hand-loaded ammunition if you intend to carry it in your defensive handgun. In many cases it is just not reliable enough to count on in a life and death situation. Carrying hand-loads can also bring liability issues. Over-zealous prosecutors have been known to make the use of “hand loaded killer rounds” a point of contention during self-defense shooting trials.

Buy a proven hollow-point design from a premium manufacture such as Federal, Corbon, Hornady, Remington, or Speer. Confirm it functions in your weapon and practice with your premium ammo on a regular basis. Now that you know you are going to be carrying hollow-points, let’s look at what caliber of firearm might serve you






The caliber of a firearm is simply the inside diameter of the barrel.  It is measured in inches or millimeters, depending on the origin of the design.  So, a 9mm pistol has an inside diameter of the barrel equal to approximately 9mm.  A .45 has a barrel I.D. of .45 inches.  Often, there are other terms applied to the simple caliber measurement.  For instance a .45 ACP is a bullet with a diameter of .45 inches and a designation of “Automatic Colt Pistol” referring back to the original design by John Browning for Colt firearms.  There is also a .45 GAP or “Glock Autoloading Pistol”.  Both cartridges use a .45-inch diameter bullet, but are not interchangeable.


In general, the larger the caliber of bullet, the more powerful the ammunition will be and more effective as a self-defense round.  It is better to carry a smaller gun and caliber and have it with you than to have a hand-cannon locked in the safe.  With that said, I recommend you carry either a .38 special with +P ammo, 9mm, 40 S&W, .357 magnum or .45 Auto as a primary defensive handgun.  There are other exotic calibers, such as the .357 SIG, 10mm, or 45 GAP that are fantastic rounds.  But, the ammunition is either difficult to obtain or very expensive.  If you carry a smaller caliber such as the .380 auto or regular pressure .38, please understand the limitations and lack of performance and be prepared to compensate with superior shot placement and volume of fire.


In order to understand the choices in caliber, you must look at each option individually.  Below is a series of photos and charts to help you understand the differences in many popular calibers.


 Left to right:  .22 LR, .25 ACP, .32 ACP, .380 Auto, 9mm, .357 SIG, .38 SPL, .357 Mag, .40 S&W, .45 ACP, and .223.


Kinetic energy is a measurement of the potential energy transferred into a target.  Many things can effect the kinetic energy such as distance to a target.  As the distance increases, the velocity at impact is lowered so the transferred energy is reduced.  If a bullet passes completely through the target as is often the case with FMJ ammo, not all of the energy is transferred as the bullet continues its flight.  Still, a comparison of typical kinetic energies is a good judge of the stopping power of a particular caliber.  As you can see by the inclusion of the .223, virtually all rifle rounds have more energy than even the most powerful handguns.






 .22 Long Rifle Rim Fire  Weapons can be small.  Ammo is plentiful and inexpensive.  May kill an attacker, but not before he kills you!  CCI mini-mag ammo is good for carrying as a back-up.
 .25 ACP  Weapons can be small.  Expensive and not even as powerful as a .22LR.  Please do not use this ammo in self-defense.  I have witnessed .25 ACP bullets bounce off glass bottles at 50' instead of breaking them.
 .32 ACP  Weapons are small.  Better than nothing.  Relatively expensive and not available everywhere.  Not a good attack stopper.  Must use FMJ ammo in order to get adequate penetration to reach anything vital.
 .380 ACP  Weapons are small.  Beginning to be more abundant and available.  A bare minimum for a primary weapon.  Marginal performance and still relatively expensive.  The use of FMJ ammo is advised to get adequate penetration.  Not a good attack stopper.
 9mm Parabellum (Luger)  Inexpensive and the most common caliber in the world.  Excellent primary weapon in 147 grain loads or 125 gr. +P.  High capacity magazines are an option.  Marginal performance with lighter loads at standard pressure.
 .357 Sig  Excellent as a primary weapon.  This round really sizzles @ 1450 feet per second velocities.  Best handgun round for penetrating hard objects.  High capacity magazines available.  Costs double 9mm ammo.  Recoil is generous and it is very loud.
 .38 Special  Widely available and cheap.  Adequate as primary weapon with 158 gr +P loads.  Compact weapon with a large variety of offerings.  Marginal attack stopping performance and limited capacity in revolvers.
 .357 Magnum  Excellent primary weapon.  Huge selection of ammunition.  Can practice with inexpensive .38 Special ammo.  Limited capacity in revolvers and generous recoil.
 .40 Smith & Wesson  Economical and widely available.  Excellent as primary weapon.  High capacity magazines available.  An ideal carry caliber.  Can have a perceived "snappy" recoil.
.45 ACP Great attack stopping ability.  Widely available.  Higher capacity magazines available outside the 1911 platform. Weapons are generally large and have limited capacity in the 1911 platform.  Generous recoil.



Bullet - a single projectile fired from a firearm.   Some mistakenly consider the entire round of ammunition to be the bullet, in actuality it is only the tip of the round.

Casing - usually made of brass and contains the powder charge, the primer and the bullet.   Before development of the metallic cartridge, the term was used to mean a roll or case of paper containing powder and shot.   Centerfire metallics include all pistol and rifle cartridges that have primers in the center of the base.

Gun powder - the general term for any chemical compound or mixture used in firearms that burns upon ignition.   The gases produced by this rapid combustion propel the bullet down the bore.   One major type is black powder, which is a mixture of charcoal, sulfur and saltpeter.   It's used in older cartridges. Another major type is smokeless powder, which is principally used in modern ammunition.   It's a granular nitrated chemical compound.

Primer - the collective term for the chemical primer compound, cup and anvil.   When the primer is struck, it ignites the powder charge.

Website Builder