View Full Version : RIM Fire - well defined

18-01-2013, 01:03 PM
Hi Gunnerz,
this is an amazing article a must read for all ...

A rimfire is a type of firearm cartridge. It is called a rimfire because instead of the firing pin of a gun striking the primer cap at the center of the base of the cartridge to ignite it (as in a centerfire cartridge), the pin strikes the base's rim.

The rim of the rimfire cartridge is essentially an extended and widened percussion cap which contains the priming compound, while the cartridge case itself contains the propellant powder and the projectile (bullet).
Once the rim of the cartridge has been struck and the bullet discharged, the cartridge cannot be reloaded, because the head has been deformed by the firing pin impact.

While many other different cartridge priming methods have been tried since the 19th century, only rimfire technology and centerfire technology survive today in significant use.

http://upload.wikimedia.org/wikipedia/commons/thumb/4/44/Centerfire_%26_rimfire_ignition.gif/800px-Centerfire_%26_rimfire_ignition.gif (http://upload.wikimedia.org/wikipedia/commons/4/44/Centerfire_%26_rimfire_ignition.gif)

http://upload.wikimedia.org/wikipedia/commons/thumb/3/30/Fired_rimfire_and_centerfire_casings.jpg/220px-Fired_rimfire_and_centerfire_casings.jpg (http://en.wikipedia.org/wiki/File:Fired_rimfire_and_centerfire_casings.jpg)

Fired rimfire (left) and centerfirecartridges.

A rimfire firing pin produces a notch at the edge of the case; a centerfire pin produces a divot in the center of the primer.

A rimfire firing pin produces a notch at the edge of the case; a centerfire pin produces a divot in the center of the primer.

Rimfire cartridges are limited to low pressure calibers because they require a thin case so that the firing pin can crush the rim and ignite the primer. Although rimfire calibers up to .44 (11 mm) were once common, modern rimfires tend to be of caliber .22 (5.5 mm) or smaller. The low pressures mean that rimfire firearms can be very light and inexpensive, which has helped lead to the continuing popularity of small-caliber Rimfire Cartridges.

.22 Long rifle

http://upload.wikimedia.org/wikipedia/commons/thumb/6/61/.22_LR.jpg/300px-.22_LR.jpg (http://en.wikipedia.org/wiki/File:.22_LR.jpg)
.22 Long Rifle – Subsonic Hollow point (left). Standard Velocity (center), Hyper-Velocity "Stinger" Hollow point (right).

Rimfire cartridge

Place of origin
United States

Production history

J. Stevens Arm & Tool Company



Parent case
.22 Long

Case type
Rimmed, Straight

Bullet diameter
.222 in (5.6 mm)

Neck diameter
.226 in (5.7 mm)

Base diameter
.226 in (5.7 mm)

Rim diameter
.278 in (7.1 mm)

Rim thickness
.043 in (1.1 mm)

Ballistic performance

Bullet weight/type

40 gr (3 g) Solid
1,080 ft/s (330 m/s)
104 ft·lbf (141 J)

38 gr (2 g) Copper-plated HP
1,260 ft/s (380 m/s)
134 ft·lbf (182 J)

31 gr (2 g) Copper-plated HP
1,430 ft/s (440 m/s)
141 ft·lbf (191 J)

30 gr (2 g) Copper-Plated RN
1,750 ft/s (530 m/s)
204 ft·lbf (277 J)

32 gr (2 g) Copper-Plated HP
1,640 ft/s (500 m/s)
191 ft·lbf (259 J)


Performance varies between barrel length and the type of action. For example, Bolt action rifles may perform differently than semi-automatic rifles. .22 LR is effective to 150 yards (140 m), though practical range tends to be less. After 150 yards the ballistics of the round are such that it will be difficult to compensate for the large "drop". The relatively short effective range, low report, and light recoil has made it a favorite for use as a target practice cartridge. The accuracy of the cartridge is good, but not exceptional; various cartridges are capable of the same or better accuracy. A contributing factor in rifles is the transition of even a high-velocity cartridge projectile from supersonic to subsonic within 100 yards (91 m). As the bullet slows, the shock wave caused by supersonic travel overtakes the bullet and can disrupt its flight path, causing minor but measurable inaccuracy.
When zeroed for 100 yards (91 m), the arc-trajectory of the standard high-velocity .22 LR with a 40-grain (2.6 g) bullet has a 2.7-inch (69 mm) rise at 50 yards (46 m), and 10.8 inches (270 mm) drop at 150 yards (140 m). A .22 LR rifle needs to be zeroed for 75 yards (69 m) to avoid over-shooting small animals like squirrels at intermediate distances.

As a hunting cartridge, rimfire are mainly used to kill small game. It is highly effective on squirrels and rabbits at distances closer than 150 yards (140 m) and on ground hogs, marmots, and foxes closer than 80 yards (73 m). It has been successfully used on large creatures such as coyotes, but range should be limited to no farther than 65 yards (59 m); head and chest shots are mandatory with the most powerful .22 cartridge the hunter can use accurately.

Because a .22 LR bullet is less powerful than larger cartridges, its danger to humans is often underestimated. In fact, a .22 LR bullet is capable of inflicting very serious injuries (e.g. the four people wounded during the Reagan assassination attempt) or death e.g. the Kauhajoki school shooting (11 killed and 1 wounded), the Jokela school shooting (9 killed and 12 wounded), or victims of Brenda Ann Spencer (2 killed and 9 wounded) as well as the assassination of Robert F. Kennedy. Numerous other shooting incidents have demonstrated that .22 LR bullets can easily kill or seriously injure humans. Even after flying 400 yards (370 m), a .22 bullet is still traveling at approximately 500 ft/s (150 m/s). A standard rimfire cartridge can have a ballistic range of up to 1.5 miles (2,400 m). Ricochets are more common in .22 LR projectiles than for more powerful cartridges as the combination of unjacketed lead and moderate velocities allows the projectile to deflect – not penetrate or disintegrate – when hitting hard objects at a glancing angle. A .22LR can ricochet off the surface of water at a low angle of aim. Severe injury may result to a person or object in the line of fire on the opposite shore, several hundred yards away.

Rimfire bullets are generally either plain lead (for standard velocity loads) or plated with copper or gilding metal (for high velocity or hyper velocity loads). The thin copper layer on the bullet functions as a high velocity lubricant reducing friction between the bullet and the barrel, thus reducing barrel wear. It also prevents oxidation of the lead bullet. Lead tends to oxidize if stored for long periods. Oxide on the bullet's surface could increase its diameter enough to either prevent insertion of the cartridge into the chamber, or – with hyper velocity rounds – cause dangerously high pressures in the barrel, potentially rupturing the cartridge case and injuring the shooter. Standard and subsonic cartridges use a wax lubricant on lead bullets for the same purpose at lower velocities.

18-01-2013, 01:30 PM
very informative, thanks for sharing

18-01-2013, 01:30 PM
nice info !

keep it up

18-01-2013, 08:52 PM
thanks for sharing. very informative...

18-01-2013, 10:41 PM
Very informative share bro. Thanks for sharing.....

18-01-2013, 11:37 PM
Very nice information bro.

19-01-2013, 10:42 AM
Thank you for sharing.

Cool Hunter
19-01-2013, 11:01 AM
nice info
thank you brother

19-01-2013, 12:41 PM
thankyou so much for this article... very informative.. for me atleast :)

19-01-2013, 06:27 PM
nice share

20-01-2013, 04:34 PM
very informative...thanks for sharing.

21-01-2013, 10:18 PM
Thanks mate !

21-01-2013, 10:29 PM
very nice share thanks

Riz Khan
22-01-2013, 04:57 AM
May Allah SWT give you a lot of Ajjar for this info share mbkhan saab - i was meaning to ask this question :) thank you sir


22-01-2013, 09:40 AM
Very nice information bro.. thanks for the share.

29-01-2013, 10:22 AM
Salam All,
Very Very well explained, also if I may... this is why one should make it a habit of avoiding to dry fire rimfire firearms.

29-01-2013, 02:14 PM
Well Defined and Well Projected Post .. Thanks mbkhan Bro :)

29-01-2013, 03:13 PM
Thanks everyone!!

05-02-2013, 09:08 AM
a perfect example.