Barrel burnout is a condition in which the rifling inside of a barrel wears down to the point that it noticeably affects accuracy. The condition is also sometimes referred to as a barrel that has been “shot out.”
As a general rule of thumb, this is a topic that is reserved for those that shoot high-powered big-bore rifles. Large rifle cartridges burn a lot of powder and produce very high pressures that accelerate barrel wear.
You don’t hear this sort of thing spoken about in small-bore, pistol caliber circles – but it affects all rifled firearms to some degree or other.
Basically, what happens is, as you force round after round through a firearm’s barrel, the rifling’s lands physically wear down. Rifling wears most noticeable from the muzzle to the crown, making it difficult to diagnose as you can’t literally see the wear at the crown.
How long this takes will vary according to the specifics of the barrel as well as the cartridge in question. As stated, higher-powered, shouldered cartridges result in faster barrel burnout. Lower power cartridges, like handgun cartridges, produce lower pressures that correspond to much slower barrel wear.
Take, for instance, a straight-walled cartridge like a 9mm that produces fairly low pressures and velocities. A 9mm barrel should last anywhere from 20,000 to 30,000 rounds or longer before you can notice any signs. Some estimates rest higher, near 50,000.
But let’s say you’re one of the lucky few that has an MP5. If you’ve had it for years and years and it has its original barrel, you might be getting close to that point.
If so, and you suspect MP5 barrel burnout, here’s how you can check, and what you can do about it.
Symptoms of Barrel Burnout
The signs and symptoms of barrel burnout can hide behind plausible deniability. Natural variance in hand loads, human error, and other factors can also cause loose groupings that can mask barrel wear.
But, if you’re confident you can hold all the other factors steady, what you’ll start to notice with barrel wear is groups that are consistent – up to a point.
Errant shots, outliers, sometimes called fliers, which you can’t account for in any other way, are a big indicator of barrel wear. If you have shots that walk all over the target at extended ranges, even when you use the same ammo, when you disassemble the platform later for maintenance break out the borescope and take a look.
How to Check
Unfortunately, even with the MP5’s barrel removed, you won’t be able to diagnose barrel burnout just by looking through the chamber towards the muzzle. You’ll need a borescope and a practiced eye.
If the rifling seems faded towards the chamber but more pronounced towards the muzzle, that’s a big red flag.
If you’re not confident making this judgment call yourself, you can, of course, take your MP5 to a gunsmith and have the shop diagnose it for you. As we said, it’s exceptionally rare with firearms of this caliber – but it does happen.
Simple (Enough): Replace the MP5 Barrel
If you do come back with a positive diagnosis of barrel burnout, there is only one thing you can reasonably do – replace the barrel.
And, whether you own an actual MP5 or an American-made version like the ZF-5, there is an easy, affordable solution. Just get a compatible MP5 barrel.
Zenith Firearms (ZenithFirearms.com) sells MP5-compatible barrels that work with the ZF-5, SP5, and other full-size 9mm roller-delayed blowback firearms.
Their mil-spec barrel is made from cold-hammer forged 4150 CMV steel and features a ferric nitrocarburized (FNC) treatment to protect against wear and corrosion. It also features a threaded end with a 3-lug mount for attaching muzzle devices.
You might even like it better than a factory original, but at any rate, if your rifling is worn, you need to replace the barrel and this is one of the best options on the market.
You can learn more at their website via the link above or by contacting them at 434-202-7790.