full metal jacket
 

i have herd that FMJ rounds are hard on barrels and shorten barrel life, any truth to this ? a freind got some from cabelas and likes them. i know there is little expantion,but there cheap, kinda like coyote prices.

RE: full metal jacket
 

Absolutely no truth at all! Even armor-piercing bullets improve the accuracy of a barrel for the first 2,000 rounds or so! FMJ bullets are made of the same materials as are softpoint bullets. The only difference is the softpoint has the core inserted from the front of the jacket, and the FMJ's core is inserted from the rear!

Actually, what ruins barrels is the cutting-torch effect of the hot propellant gasses. These gasses act like a cutting torch, melting the barrel steel and carrying away an infinitesimal amount of steel each shot! The higher the velocity and gas pressure, the faster this happens, as well as shooting too much without letting the barrel cool between shots.

RE: full metal jacket
 

What eldeguello said.

If you ever get the opportunity to look at a worn out barrel, you'll notice that the wear starts from the throat at the chamber end and moves progressively forward. Since the bullet velocity, and therefore friction and force, are greatest at the muzzle, and yet the muzzle is the last part of a barrel to show wear, it obviously indicates that the bullet is not the culprit of barrel wear.

It's the very intense heat and pressure of the gasses at the throat that literally erodes the rifling away, much like water erodes rock over time. This is why it's important to keep your barrel cool when shooting. The hotter the barrel gets, the softer the steel, and the faster the gas can erode it away. Allowing the barrel to remain cooler by shooting only a few times (2-5 shots in a row depending on the cartridge, with higher capacity cases creating more heat and wear than their smaller bretheran) and then allowing the barrel to cool will greatly extend barrel life.

Mike

RE: full metal jacket
 

Does this happen with .22's as well? (I am assuming it does) Does it happen as quickly? I remember plinking with my old Walther .22 and shooting cartons of rounds untuil the barrel was very warm. Im hoping I didnt do too much damage to the barrel.

RE: full metal jacket
 

.22's I wouldn't worry about too much, its takes 100s of thousands of rounds to wear out a .22 barrel, though if you rapid fire it every time you shoot it for extended shooting sessions, I would imagine that you might become one of hte few people to ever wear one out.


There is some porportion to the the amount of powder you burn and how fast the barrel wears out. Small caliber large cased magnums tend to burn out barrels really fast, while mild middle of the road .308/30-06 barrels last a lot longer.