by GCA member Bob Garr

Pose the question,  which is the heart of a gun, more specifically a rifle, the receiver or the barrel? Well, if you tried to fire a cartridge with only a receiver I doubt that much would come of it. On the other hand, if all one had was a chambered barrel the argument could be made that a cartridge could be properly placed in the chamber and if you so wanted to, or were a Troglodyte or Neanderthal, pound on the cartridge case head with a rock or a stone hammer until it discharged. Why a thinking man would want to do so I couldn’t say. But, it would likely fire, and MAY even permit the bullet to travel and exit the barrel. Thus showing it to be the heart of a gun. Spectacular  logic!!! But in all seriousness, the barrel is a very critical component of a firearm.  I’m not going to dwell on shotgun and handgun barrels. But leave the main focus to rifles. I feel rifle barrels demonstrate a broader scope of characteristics than shotgun or handgun barrels do. To start, with the exception of SBR’s, the shortest length of barrel allowed by Federal law is 16″. And that holds true for centerfire and rimfire rifles. Barrel length is not arbitrary, under most circumstances it has been determined by the manufacturer to be a specific length in relation to the round it is chambered for. This is done to match the cartridges internal powder charge (a relation of bullet diameter and bullet weight) so as to maximize efficiency by having all powder burned by the time the bullet reaches the muzzle. In theory. This is the primary reason why you see longer barrels on magnum chambered rifles. Rifling twist in turns per inches is another main consideration of length. Generally 26″ for magnums. On the other hand you see barrels in the 22″and 24″ range for non magnum chamberings such as ,223 / 5.56 × 45,  .308 / 7.62 × 54, .30 – 06, . .270 win, .22 – 250 etc. In many cases this class of cartridge may even make sacrifices to velocity and muzzle energy to make a compact rifle. This can be seen in rifles such as the following . The Remington 742 / 7400 series and Remington 760 / 7600 series with their shorter than 24″ barrels on their “Carbine” versions of these rifles. Or the Marlin and Winchester carbine versions of  their lever actions, such as the 336, 1895 and the 1894 respectively . Other obvious examples of this are Springfield Armory’s M1-A and the M1-A SOCOM version, the FAL and the FAL Paratrooper model and the .30-40 Krag rifle and the lovely Krag Cavalry Carbine to name but a few. Rimfires are full of examples of models that have 22″, 24″ and 26″ barrels, and their carbine counterparts of 16″ – 20″. Some examples of these are the Winchester m-62 (and it’s clone, the well made Rossi m-62) and the m-62 in 16″ SAC / gallery gun versions, the Marlin m-39 and its counterpart the model 39 Mountie, the Marlin m-60 and the Papoose to name a few. Now, for something all barrels have, and yet for something with such commonality it can still be very different. As the saying goes “It’s the same, but different “.  And so goes a barrels rifling. Rifling can be what makes the difference between a firearm  being classified as a rifle / firearm or  “any other firearm or destructive device. Which can amount to lots of paperwork, questions and headaches to be sure . Especially if you live in an area that does not permit ownership of  smooth bore rifles, even though the ATFE says they are permitted as long as the correct form and tax stamp fee is rendered unto the ATFE / Treasury  Department.  Anyways, being what distinguishes rifles from shotguns, rifling has been used for quite  some time. Devised as a means to stabilize a projectile in flight, many different methods have been used over time to achieve this. The first lesson to learn after the establishment of the principal of spiraled groves to stabilise the bullet was determining whether a left hand or right hand  twist was beneficial and at what rate per inch it should be. I don’t want to get to far off track by discussing methods of actually rifling the barrel. But some methods used have been hammer forging  and  button rifling,  Types of rifling are the traditional land and groove common today. A variant of this is the so called polygonal rifling where the lands are not cut with 90° edges. But rather the lands edges are cut at an angle and do not exhibit  the traditional 90° edge. Another form of rifling that has been used in the past is the British Gain Twist Rifling. The idea here was that the rifling assumed the standard twist rate for the projectile used, but as the bullet traveled down the bore the twist rate increased, dramatically. Another British type is Metford rifling. This was introduced with the Lee Medford in time for the Boer War. It was a shallow 7 land and groove design invented by Henry, of Henry rifle fame. The pattern of the lands and grooves were not angled,  but rounded. It seems the British experimented with various types of rifling more so than others. And judging by their notable absence today they were not very beneficial. But remember, you can learn as much from failure as from success when testing in uncharted waters . A more recent example is the now popular 5R rifling . It uses only 5 lands, which have angled sides rather than the 90° conventional style. More notable is the placement of the lands. Having 5, they are positioned to always be opposite a groove. Conventional rifling has lands opposite another land. Who’s to say which is better? Most shooters could never obtain half the accuracy their rifles are capable of. PART  –  2 Let’s look at barrel thickness and profile. It has long been known that the larger a barrels diameter is the better it will shoot,  generally speaking. So why would that be? Well, there are a number of reasons. First off is rigidity.  The thicker a barrels OD is in relation to it’s bore, the less prone it is to vibration.  Here again barrel length plays a role. Barrel vibration and its harmonics are directly related to length and diameter. Altering one or all may find or loose the “sweet spot” of an individual barrel. Profile and thickness will play a role in heat build up and dissipation. Heat can directly affect point of impact. This is a noticeable and quantifiable phenomena  demonstrated by shooting from a cold bore compared to a warm bore and a hot bore. Inconsistency and stringing are byproducts of a hot barrel. Also a factor is chamber thickness and the area directly in front of it. Besides having to contain cartridge detonation and pressure, these are likely to be the areas of greatest heat generation and transference. As such, the way the chamber “sees” the cartridge can change proportionally with an increase in heat. The interrelationship between these factors can be readily seen in man’s solutions to the problems. As such, increased barrel diameter for rigidity. Fluteing for increased surface area. Barrel length for vibration, harmonics and efficiency of powder charge are all factors in barrel length, profile and thickness. As the last thing a bullet sees when leaving the barrel, the muzzle is very important. Any imperfections, deformations or fouling will negatively affect performance. Polishing and chamfering the muzzle to address these issues helps greatly. As does cleaning. Selecting the type of muzzle crown can greatly protect your muzzle. Possible options include the flat cut 90° muzzle. It works well but is prone to damage. The recessed target crown is my favorite. It offers the flat cut muzzle at 90° but with the protection of a stepped recess. Also available are the 45° and the 79° (11°) profiles. Which ever is used, make sure that you treat it well and never allow it to be abused.  That would include not using steel cleaning rods, stainless bore brushes, protecting the muzzle and not storing in a muzzle down manner. And NEVER clean from the muzzle! If your barrel has sights, fine. If you remove them use plug screws to fill the screw holes. If you decide you are going to play kitchen gunsmith for the day and drill and tap your barrel, be ABSOLUTELY sure of what the safe depth to drill is. Holes drilled to deep or mistake holes filled with plug screws can pose a serious injury hazard. The pressure in the barrel can blow thru these thinned areas, and if plug screws are used they can be blown out going right through your hand or worse. To aid in accuracy some manufacturers or barrel makers suggest that it may take 100 or so rounds to break their barrels in. Others  suggest lapping the bore, either by hand or by firing special projectiles coated with various grit lapping compounds. This will polish the bore. For bore protection, some barrels are chrome lined. This is frequently done to military rifles to protect from corrosive ammo . But not always, as I have a Browning BAR sporting rifle from the mid 1970’s that has a chrome lined bore. Not sure why, but I guess Browning had their reasons. I hope some of this was helpful to the novice just starting to learn the fundamentals of barrels. As the title says, “Basics “. To many people a barrel is just a tube, a piece of pipe that the bullet comes out of. Understanding the basics will show that it is so much more.