View Full Version : Ever wear out a barrel?
I know that .mil and hard training LEO's can wear out barrels. I believe that the service life is between four and ten thousand rnds? But they use them hard. I was wondering if any here not .mil/leo has worn one out doing classes and training?
Also, would you expect some one who is not .mil/leo but does classes and trains regularly to wear out a carbine barrel significantly quicker than a mid-length barrel?
I know it would take a lot of rnds...kinda wondering how many.
I'm just curious...how do you truly know when it's worn out?
The most reliable way is to check the throat erosion. That and the headspacing will be the two major issues that will make the weapon unsafe as the round count gets up there.
The most reliable way is to check the throat erosion. That and the headspacing will be the two major issues that will make the weapon unsafe as the round count gets up there.
cool thanks. But hey, u care to elaborate on throat erosion and headspacing? I have a general idea of what headspace is, kind of.
This gauge (http://www.brownells.com/.aspx/pid=8761/Product/THROAT_EROSION_GAUGE) will help you see the throat erosion. Basically, when you fire a round, hot gases escape around the bullet as it leaves the casing and that effectively makes a larger chamber in which the round will sit. With that gauge, the farther it goes into the barrel when compared to new, the more erosion is present and the more worn the barrel is. Head spacing deals with how far the round will chamber. As the barrel and bolt wear, the round will seat deeper and there will be more room for it to move or expand as it is fired. This also is not desirable as the casing becomes less supported.
eightmillimeter
10-08-09, 17:56
The throat is the are of the barrel immediately ahead of the chamber that experiences the greatest heat and friction. This area will wear out first, and accuracy will suffer. The bore itself sees little to no wear, and the crown can be worn out or damaged by improper cleaning techniques and high volumes of fire.
A carbine barrel will not wear out faster or slower than a midlength, the throats are getting the same amount of punishment no matter where the gas port is.
Headspace is simply a precise measurement of the length of the chamber, from the bolt face to a specific point on the case shoulder area (when talking about 223). As the barrel and bolt age, the chamber will get longer (excessive headspace) eventually causing popped primer, case head separations, poor accuracy, and even the occasional catastrophic failure (KaBoom).
If you want a barrel to last longer don't let it overheat, use quality cleaning products and don't over clean.
This gauge (http://www.brownells.com/.aspx/pid=8761/Product/THROAT_EROSION_GAUGE) will help you see the throat erosion. Basically, when you fire a round, hot gases escape around the bullet as it leaves the casing and that effectively makes a larger chamber in which the round will sit. With that gauge, the farther it goes into the barrel when compared to new, the more erosion is present and the more worn the barrel is. Head spacing deals with how far the round will chamber. As the barrel and bolt wear, the round will seat deeper and there will be more room for it to move or expand as it is fired. This also is not desirable as the casing becomes less supported.
Damn! Did u copy and paste that lol?!?!?!
Very well put sir ;)
I understood that very easily.
Thank you for that.
Even SS barrels can last over 10-15k rounds and still be very accurate.
The throat is the are of the barrel immediately ahead of the chamber that experiences the greatest heat and friction. This area will wear out first, and accuracy will suffer. The bore itself sees little to no wear, and the crown can be worn out or damaged by improper cleaning techniques and high volumes of fire.
A carbine barrel will not wear out faster or slower than a midlength, the throats are getting the same amount of punishment no matter where the gas port is.
Headspace is simply a precise measurement of the length of the chamber, from the bolt face to a specific point on the case shoulder area (when talking about 223). As the barrel and bolt age, the chamber will get longer (excessive headspace) eventually causing popped primer, case head separations, poor accuracy, and even the occasional catastrophic failure (KaBoom).
If you want a barrel to last longer don't let it overheat, use quality cleaning products and don't over clean.
Thanks also!
I didn't know u could over clean. I am anal retentive when it comes weapons cleaning lol...maybe I should just chill and shoot more/clean less eh?
Outlander Systems
10-08-09, 18:55
Thanks also!
I didn't know u could over clean. I am anal retentive when it comes weapons cleaning lol...maybe I should just chill and lube more/clean less eh?
Fixed that for ya.
HD1911:
Your accuracy will begin to suffer upon the barrel reaching the end of its service life.
Just an FYI. The military gage differs significantly in design from that gage. I don't know how much I would trust that specific gage to get an accurate reading.
This gauge (http://www.brownells.com/.aspx/pid=8761/Product/THROAT_EROSION_GAUGE) will help you see the throat erosion. Basically, when you fire a round, hot gases escape around the bullet as it leaves the casing and that effectively makes a larger chamber in which the round will sit. With that gauge, the farther it goes into the barrel when compared to new, the more erosion is present and the more worn the barrel is. Head spacing deals with how far the round will chamber. As the barrel and bolt wear, the round will seat deeper and there will be more room for it to move or expand as it is fired. This also is not desirable as the casing becomes less supported.
Ok, two cents on this:
Over the years I have seen 100 or more bbls wear out on .mil guns.
In my experience the throat erosion gauge is not a very accurate tool. Throat erosion in the M4 usually occurs 1-3 inches past the case mouth. The tool does not go deep enough.
In you average M4, you will detect bore wear long before you detect throat erosion. Even though the throat may be ruined and you accuracy is crap.
IMO, the best way to detect a worn bbl is to reconfirm your zero from time to time. When you see your shot group open up and you know you are doing your part, it is a good indication that your bbl is getting shot out. Depending on your duty cycle this will happen around 10-20k rounds.
Won’t the rifling be worn out? What’s the barrel life for semi autos?
Robb Jensen
10-08-09, 21:28
The throat erodes much faster than the headspace.
I usually replace a barrel when it will no longer group well at 100yds even after a good copper cleaning and crown cleaning. This means while freefloated and to me well means less than 5MOA (if using a red dot sight, chrome lined barrels) or 2MOA if using magnified optics (usually stainless or non-chrome lined match grade barrels). These always still headspace just fine.
Ok, two cents on this:
Over the years I have seen 100 or more bbls wear out on .mil guns.
In my experience the throat erosion gauge is not a very accurate tool. Throat erosion in the M4 usually occurs 1-3 inches past the case mouth. The tool does not go deep enough.
In you average M4, you will detect bore wear long before you detect throat erosion. Even though the throat may be ruined and you accuracy is crap.
IMO, the best way to detect a worn bbl is to reconfirm your zero from time to time. When you see your shot group open up and you know you are doing your part, it is a good indication that your bbl is getting shot out. Depending on your duty cycle this will happen around 10-20k rounds.
I happened to escort the Small Arm Lead at the DCD from the Infantry center into my old arms room a few years ago. We had been talking about many issues with weapons systems and one that we happend to be discussing was service life of the M-4. At the time our Infantry BN's had been running around 9,000 rounds a year through their carbines in training. We had been doing so for at least 5 years, this was in 2005 or so. We grabbed three random rifles off the racks and looked them over. What stood out right away was that the rifling was only faintly visable in the barrels. This from a arms room of 100+ rifles.
We called the TACOM LAR down after. He gaged the whole rack for each of the rifles that we spot checked with the trusty throat erosion gauge. All the weapons passed:( so they had to be good to go. Lands and Grooves are not a inspection requirement.
It's a measure, but I'm not so sure it's a good one. There are other ways you can get a barrel to be coded out, but very few Infantry units are resoursed to do it time wise. I'm not sure how this is being addressed now when the SARET Teams TI weapons during Re-Set.
My guess is that it isn't being addressed. This also came up during the Colt course that I just attended and the instructor was in the opinion that when your groups start opening up, then it's time to change the barrel out.
Maybe a better question to ask is; How much accuracy do you need? If you say that you need to be able to hit a man size target at 300M and your groups were tight and now they have opened up to 5" or 6" inches can you live with that? I think I could. To others that may be unacceptable.
I happened to escort the Small Arm Lead at the DCD from the Infantry center into my old arms room a few years ago. We had been talking about many issues with weapons systems and one that we happend to be discussing was service life of the M-4. At the time our Infantry BN's had been running around 9,000 rounds a year through their carbines in training. We had been doing so for at least 5 years, this was in 2005 or so. We grabbed three random rifles off the racks and looked them over. What stood out right away was that the rifling was only faintly visable in the barrels. This from a arms room of 100+ rifles.
We called the TACOM LAR down after. He gaged the whole rack for each of the rifles that we spot checked with the trusty throat erosion gauge. All the weapons passed:( so they had to be good to go. Lands and Grooves are not a inspection requirement.
It's a measure, but I'm not so sure it's a good one. There are other ways you can get a barrel to be coded out, but very few Infantry units are resoursed to do it time wise. I'm not sure how this is being addressed now when the SARET Teams TI weapons during Re-Set.
I should have been clearer. In most units the only grouping a soldier ever see's are those fired at 25 meters zeroing or doing alt C qualification. Spotting a group opening up at that range is just about impossible. Adding to theissue it is not uncommon for soldiers to change weapons, in garrasion, often. This means it is hard to see changes in a weapons performance over time(and most soldiers would not notice the differance anyhow).
One way you can get a barrel coded out is if the rounds are keyholing. At 25 meters this can be quite a feat to spot in all but the worst barrels. On the Army qual ranges you only have to hit the target round placement does not count. You don't go down range to see if your rounds are keyholing. Even if you did the targets are so full of holes you could never say if one was yours.
Even for the odd unit thatpulls targets on a KD range keyholing will often be overlooked. It is not something taught as a symptom to look for. For that matter there are a host of issues you could go into about lack knowledge at the small unit leaders level on weapons and marksmanship training.
I've had M4 barrels that needed to be replaced, as identified during semi-annual weapons gauging. I believe an M4 barrel is rated for about 7,000 rounds-as we all know a lot depends on how fast those rounds were fired.
But, in the case above, the Colt M4's were issued brand new in the box, and during the semi-annual gauging a number of them needed to be replaced about 6 months later. I did not dig into the amount of throat erosion due to time concerns, but 7,000-10,000 or more rounds sounds about right.
Belmont31R
10-10-09, 00:36
Military guns are going to be run harder than your average civilian gun.
The most important issue from what I have gathered is how the barrel is shot. An easy 200rds over 10 months is going to show far less wear than a barrel shot 2k rounds in a single day.
Military standard issue cleaning rod is non-coated steel.
M855 is hotter ammunition than your average 223 load.
Ive seen M249's get a few thousand rounds put through them in under an hour, and barrels at night bright red hot.
I also have one stainless barreled gun that has about 6k rounds through it in a couple of years, and it still shoots sub-moa quite easily with good ammo. I used to have another one with about 4k rounds that was shot a lot harder, and went from sub-moa to 1.5-2moa pretty quick.
This past weekend I also managed to turn my Triple Tap brake colors because I got it so hot...wanted to put it through its paces....haha
Key-holing and loss of accuracy are the two biggest indicators to look for, however.
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