The Reloading Press is an at-least-weekly feature here on Gaming Ballistic for 2016. Each week it looks at some interesting real-world cartridges and presents them with hopefully-useful information in GURPS Format.

.22 LR/5.6x15mmR

The .22 LR was designed just shy of 1890, as a modification – or at least inspired by – the Flobert BB cap and the .22 S&W of 1857. It was originally a black powder cartridge, and the various loadings and velocities reflect the range from “indoor target use against not-much-other-than-paper” to “wartime use in WW2 in suppressed pistols” to “varmint killin’,” with a lot of plinking and competitive shooting in between.

The fairly low cost and extremely versatile design make it one of the most popular, if not the most popular, chamberings for firearms in the world. The low recoil, high accuracy (remember: Olympics), and general ease of loading and shooting, plus the traditionally low cost (recent shortages in the USA are somewhat of an aberration) make it a great chambering to teach marksmanship, firearms handling, and discipline.

The basic inputs will be driven from the highest energy projectile that’s a standard load: the copper-plated 31gr (2 gram) round-nose bullet fired at 1750fps. This projectile is still less than half the energy of a 9mm.
Ballistic’s Calculator Inputs

Basic inputs for the calculator are as follows, selecting 458mm (18″) for the (test) barrel length.

Chamber Pressure 25000 psi
Barrel bore 5.6 mm
Case Length 15 mm
Chamber Bore 5.6 mm
Barrel length 458 mm
Bullet Mass 31 grains
Aspect Ratio 1.9 L/Bore
Burn length 10.04 mm
Projectile Caliber 5.6 mm
Total Accelerated Mass 31 grains
Expansion Ratio 1.6 expansion

Output Stats

The rated cartridge is on the higher-energy end of things, but shows behavior that more or less defines the round.

  • The velocity is at the muzzle. The velocity with the 18″ test barrel is tuned to match the 1750fps for a 31gr bullet. There are many other loads available, but my practice is to take the highest energy commonly listed.
  • The .22LR, even in hollow-point, do not expand enough to give any GURPS benefit for wounding – that is, even a JHP will not expand enough to eke out pi instead of pi-. So the damage is pi- from the muzzle to the limits of range.
The notable features of the .22LR includes the quickness with which the velocity plateaus: once you get to an 11″ barrel, you will not increase velocity enough to get to 2d+1 unless you get to a 31″ barrel . . . and even carefully tuned .22LR projectiles with slow-burning powder, in the real world, start to lose velocity out of a 26″ barrel as pressure starts to decrease faster than barrel friction is increasing. For most standard loads, the longest practical barrel is on the order of 18-19″ (460-480mm).

The literature lists the .22LR as a “150-yard” cartridge. This is due to the transition down to subsonic velocity, and the accuracy degrades measurably from that point. This coincides nicely with the 1/2D range calculated.

This is, was, and always will be an anemic cartridge that is going to depend greatly on shot placement. To the vitals out of a 5″ through 19″ barrel, you can get 6-36 points of damage – plenty enough to kill an unarmored average man. To the skull, you will get 0-40 points, with a fairly low but not unrealistic chance of the bullet deflecting off the skull. 

Anywhere else, you will need to hit a lot. 

Alternate Loads

If you go out and buy a brick of .22LR without some care for getting the maximum energy out of the load, you will likely bring home 40gr projectiles at about 1200fps out of an 18″ barrel. These carry a bit better (1/2D of around 210yds), but do even less damage (1d+2) out of an 18″ barrel. The transition to 2d-1 is at nearly 24″, making it (in reality) top out at the 1d+2 pi- level. It will drop below 1d+2 to 1d+1 at 40-100mm barrel length. So standard .22LR will be 1d+1 out of pocket pistols, and 1d+2 out of rifles.

Very subsonic .22LR exists firing a 60gr bullet at 950fps. This is a 340-yd 1/2D and is about right for 1d+2 pi- at the muzzle of a 18″ rifle. Unlike it’s lightweight cousins, it can expand in JHP format to do pi damage, but base damage drops to 1d+1. Out of a pistol with a 4″ barrel, it will do 1d (0.5) pi as a JHP round, or 1d pi- as a ball round (the copper-washed bullets do not usually qualify as having a metal ‘jacket’ to speak of).

There are snake-shot rounds firing shotshell as well. This is 30grains of #12 shot, each of which weighs about 0.2 grains (!). Wound channel modifier is on the order of 0.1, basically four size modifiers lower than even a pi- round. Penetration is notionally 2d, but this is an artifact of the 1.5mm diameter of the projectile in the model. Best to treat this as RoF 6, 2d (0.2) pi-, clustering groups of pellets together. 


There are a vast, vast number of .22LR guns out there. Some classics:

Ruger 10/22 semi-auto rifle. This 18.5″ barrel semi-auto rifle comes in a lot of styles, and is a good plinker for novice and experienced shooters alike. Comes with a 10-round rotary magazine that fits flush with the rifle, or a 25-round box.

In a pistol, the small form factor and low recoil of the round makes it fairly attractive for attaching accessories . . . such as a suppressor. This would include the Walther P22 pictured to the right. This shows a 3.4″ barreled pistol with a suppressor that is as long as the overall firearm itself. 

An unusual .22 LR pistol is the Calico M110, whose helical-fed magazine holds 100 rounds of .22LR. It’s a very unusual looking pistol (and also available in 50- and 100-round capacity as the M950/960 in 9mm) and if you need 100 rounds of .22LR on tap in an otherwise bulky gun, this is what you want. The rifle-length barreled versions are apparently fairly attractive conversions to full-auto, due to low recoil -effectively a precursor to the 4.6x30mm and 5.8x28mm PDW-style weapons with roughly the same projectile weight but using a bottlenecked round to get a lot more energy out of the package.

The concept of the suppressed .22LR has been around for a long time, and saw service as the Ruger High-Standard HDM in WW2. This modified Ruger Mark 1 (and later, Mark II and Mark III) is purpose-built for the role.

Without providing a picture, it should also be noted that conversion kits – often a magazine well insert, a new chamber/barrel, or (in the case of the already-.22″ caliber AR15) simply a new bolt assembly – for many firearms are available, allowing you to swap your usual caliber for the usually less expensive .22LR. This can be especially attractive given that  1,000 rounds of .22LR can be had for $150, while 1,000 rounds of 62-gr M855 style ammo will run about $350-400. 

6 thoughts on “Reloading Press: .22LR

  1. We have something of a mismatch between your figures and published GURPS stats for rifles in .22LR, all of which are 1d+2 pi-. Your example is for quite high-powered ammunition, but the damage boost is somewhat more than the +10% for +P ammunition on p165 of High-Tech. Any suggestions?

    1. First paragraph of Alternate Loads gives a load that's 1d+2 pi- out of an 18" barrel. The damage boost from 1d+2 to 2d is a bit higher. Two things: I will often see my damage values for *high* energy about 5-10% high. But also, differences are to be expected at some places. The legacy GURPS values were not necessarily rationalized from edition to edition.

      In short, I'm comfortable with the differences. To the extent my model is accurate as opposed to merely self-consistent, it probably produces good values.

      When the new Vehicles Design comes out one day/month/year, it will have a weapons design system that looks similar to, but produces slightly different values than, my own. When that comes out I may well revise my article and my spreadsheet accordingly.

    2. +P ammo for 1d+2 LR is 2d-1, but it hardly seems a huge stretch for optimal grain, powder and barrel to get up to 2d in rifles, to me.

      Doug, if I might ask, what would be a good ammo coming out to 2d in comparison to the basic 40gr stock stuff? Is that like a magnum round?

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