Gun Safety Tips: Bore Obstructions

by
posted on October 12, 2020
mentor-gun-cleaning-screen-shot.jpg
A gun's bore is defined as "the interior of a barrel forward of the chamber." Any object in the bore that impedes the progress of the bullet toward the muzzle has the potential of raising pressures to a hazardous level. There are many types of objects that can serve as bore obstructions: cleaning patches, snow, mud, dirt or other material that may be collected from the environment; even bullets from a squib load or portions of a bullet jacket. The results of a bore obstruction vary, depending upon the thickness of the barrel walls, strength and type of action, the pressure of the cartridge, the weight of the obstruction and where the obstruction is located. 

An obstruction in or just forward of the chamber has the effect of augmenting the weight of the bullet or shot charge, and therefore increases chamber pressure. The potential for damage to the firearm depends upon the amount of this pressure increase, the construction of the action and breech, and the strength of the case. If the increase in pressure is only moderate, little or no damage may result.

An obstruction in the middle or forward part of the barrel may cause a ring bulge or, in some cases, bursting of the barrel at that point. This damage results from the impact of the projectile(s) with the obstruction. The weight of the obstruction , speed of the bullet or shot charge, and thickness of the barrel wall determines the extent of the damage. Cases have been seen in which a separated bullet jacket in the bore caused a small ring bulge and was ironed into the bore at that point, allowing the passage of subsequent bullets without other signs noticeable by the shooter.

Occasionally, a burst shotgun barrel is produced when a too-small shell is inadvertently dropped into a shotgun chamber and becomes lodged in the bore, and is impacted by the shot charge or slug of a subsequent shell. This can happen with a 20-gauge shell mistakenly inserted into a 12-gauge chamber: The undersized shell is lodged forward of the chamber and the shooter, seeing an empty chamber, loads a 12-gauge shell into that barrel and fires it. In this scenario, the 20-gauge shell not only acts as a bore obstruction, but itself often fires when hit by the 12-gauge load.

Barrel damage from defects in the structure or material of the steel (such as the bursting of a Damascus barrel fired with high-pressure smokeless powder loads) presents a different appearance than damage resulting from an obstruction. Also, while a heavy obstruction in the chamber end of the barrel may indeed damage an action, those in the middle or forward part of the barrel (such as occur when mud or snow get in the muzzle) may damage only the barrel and not the action.

Fortunately, it is fairly easy to avoid the hazards of bore obstructions. After cleaning the bore, visually inspect it from the breech end for patches or other objects. In the field, keep the gun's muzzle away from snow, water and mud. At all times, if a squib load is suspected, unload the firearm, open the action and ensure the bore is clear, either by visual inspection (from the breech end!) or by running a cleaning rod the length of the bore.

Latest

Staccato Xl Lede
Staccato Xl Lede

Video Review: Staccato XL Double-Stack Pistol

This hammer-fired, competition-ready handgun is the epitome of "Go Big Or Go Home."

Fun Friday: Life at 68 Below Zero

Chinook winds, overturned boats, bear charges...and so many wonderful tales to tell!

Grandparent's Guide to Teaching Gun Safety

Grandparents make great mentors thanks to their patience and love. Here are six terrific tips to make it work for your family, too.

Throwback Thursday: Remington Cane Gun

No, it wasn't designed by 007's Q Branch...it's real.

Reviewed: Kimber Mako R7 Semi-Auto Pistol

The best seat at a poker table is the one that’s last to act ... and Kimber's Mako R7 is the winner in your hand.

Trigger Pull Weight: Is Lighter Always Better?

Short answer: It all depends on the shooter, the gun and its intended purpose. Complete answer: See below!

Interests



Get the best of NRA Family delivered to your inbox.