Barrel Length and brass wear

[Cokie]

Does firing brass cased ammo preserve brass life if a longer barrel is used? Would a 20" barrel, as designed by Stoner, be more gentle on brass and easier to reload than on a 14.5" barrel?

[Auto-X Fil]

No. Brass life only has to do with peak pressure, which is based entirely on the load.

Now, an overgassed system can rip off case rims, but that's not really a "brass life" issue as the term is normally used!

[Coal Dragger]

As stated barrel length shouldn't have any direct affect on brass longevity. It's all about pressure, then chamber dimensions, and lastly how the brass is then treated after firing.

For example pressures being equal, a bolt action rifle with a tight match chamber with minimum headspace will not allow the brass to be worked as much as a semi-auto with a looser chamber. Plus the bolt action can be manipulated to allow very gentle extraction and ejection avoiding dings and dents. The bolt gun would also allow for neck sizing only, further increasing brass life.

Lots of factors but barrel length is largely irrelevant by itself. With the AR the only consideration is bolt carrier velocity due to the gas system. A properly gassed AR will be easier on brass than an over gassed AR, that has a lot to do with gas port size, it's possible to over gas a 20" barrel too.

[Cokie]

So far it makes sense.

I didn't quite get my thoughts into words on my question lol. What I meant was would the longer gas system have any effect as far as lowering pressure? I am assuming from the two answers that it won't, as the AR chamber is loose no matter short barrel/long barrel and that is going to be the most detrimental to brass.

[bigedp51]

Lake City brass and commercial contract 5.56 ammunition made for the military is the hardest of the .223/5.56 cases and will hold up longer. This came about during the Congressional hearings on the jamming problem of the M16 rifle and the brass hardness standards for military 5.56 ammunition was increased. You can't make the cases thicker because it would cut down too much on case capacity.

How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests
http://bulletin.accurateshooter.com/...ardness-tests/

The type gas system has a effect on port pressure and how much abuse the case rim will be forced to take. The over gassed AR15 will let the bolt start moving to the rear while pressure is still in the barrel. At the opposite end of the spectrum a M1 Garand has the gas port at the end of the barrel. And the bullet has left the barrel before the bolt begins to move.




Bottom line, if you do not load hot your brass should last a long time, no matter the barrel length.

[Sticky]

So far it makes sense.

I didn't quite get my thoughts into words on my question lol. What I meant was would the longer gas system have any effect as far as lowering pressure? I am assuming from the two answers that it won't, as the AR chamber is loose no matter short barrel/long barrel and that is going to be the most detrimental to brass.

The gas system length affects gas pressure to the bolt and related components in an AR, shorter barrel, higher gas pressure, longer barrel, lower, but... this really has no effect on the brass (chamber pressure) (unless severely overgassed), only the drivetrain components... lol

[markm]

Agreed. Barrel length can make the ejection smoother. But a hot load will loosen the primer pockets in either barrel.