I got my FN Scar16s for a few months now. The barrel is brand new 14 inch pinned to 16. When I first got it the throat gauge read at 3.7ish area. After shooting what I would say around 1200-1500 rounds out of it, it moved to 4.1 ring. At the present rate, that means the barrel burn will be done at about 8k-10k rounds. Curious I decided to look at the bore camera and see these.... the throat area is washing away really quickly. Sort of disappointed a $1k barrel would wear out this fast.

What sort of life span you got out of your 16s barrel?

I mean it’s a $1k barrel cause it’s FN.  or because it’s magic

What’s m4 service life like 8k?

I shot an estimated 26K rounds on the first barrel without any degradation in accuracy or muzzle velocity. In 2018, I replaced the 16 inch barrel with a 14 inch barrel and B.E. Meyers 249F, and the only reason I replaced it was simply because I wanted a shorter barrel with stellar flash suppression, but not because the previous barrel was degrading. That said, there were no indicators that the 16 inch barrel was anywhere near close to the end of its service life when I replaced it.

Tons of variables related to service life. Excessive heat from long strings of continuous fire, or high volumes of rapid fire, will definitely cause a barrel to degrade prematurely, as will excessive fouling from suppressor use, fouling from corrosive ammunition, abnormally high pressure ammunition, etc.

Also, round-counts have variables attached to it. The results of 30K rounds shot over the span of 10 years is going to be much different than the results of 30K rounds shot over the span of 2 years.

Are you shooting Russian steel case ammo?

I'm at 1000 rds and still going strong......................

What gauge have you been using to measure the throat?

No, I'm shooting brass. The IMI M193, Federal M193, and the Hornady M193 type.



I'm not sure of the brand. I bought it off fulton-armory so I assume it is good to go. It works well on the AR.

I do believe the throat is uneven. I just tried the throat gauge again and 6/10 times I get 3.7. But sometimes the gauge can go in a little more and read at 4.1. I'm thinking the landing is cut unevenly on this particular barrel. I'm going to shoot it until it dies though.

You should send it to FN for replacement.

Wow, I would have FN inspect it

My first 16” barrel has over 15k rounds; only reason i got it off was the 10” fb barrel installed and that one had 17000 rounds and mostly supressed; just replaced it with another 10” fn barrel over the holidays last year but have not shot it much so far. This is since 2014 so 8 years of data. I shoot brass ammo. These things run clean with minimal stress on parts and even at high round counts maintain decent accuracy.

Damn has accuracy changed? I know when FN was making AUG barrels for Steyr US, some of their later batches had chrome flaking issues like this after 4k rounds. This made Steyr US switch to their own in house made ones.

Let us know what FN warranty service says

OP:

So you used this gauge:
https://www.fulton-armory.com/throat-erosion-gauge-ar-15.aspx
to gauge your SCAR?  Correct?  

How exactly did you use the gauge and what did you align it with when taking the measurements?

Yes I used that gauge. I take the upper and simply flip it upside down and put the gauge in to read it from the bottom. This way it is perfectly in line with the end of the barrel extension. Reading it 10 times, I get different readings.

I shot the SCAR16 more. I have a spare 14 barrel so I'm not too unhappy. Looking at my spare barrel, it looks much, I mean much better.

So tell FN

You are doing it wrong.  Your datum zero point is wrong.  It is an AR gage, designed for use in AR’s.  Most AR’s I gage with that are at zero, or less.  Heavy worn barrels are maybe like 4-6, etc.  Even “used” barrels gage really close to zero typically (most people don’t shoot that much).  And it depends on if there is chrome lining or not as well, for example Colt chromed vs Colt ban era un-chromed.    

I believe a rule of thumb (at best) is that 1000 rds or so gets you approx 1 measurement of movement in some match barrels.  Military rifles might be rejected when they read at 10 or higher.  Some shooters consider 5 to be worn out for competition needs.  

None of that means anything in a SCAR.  The gage, even in an AR is just for monitoring wear.  Most new Colt AR’s will be less than the zero line in my experience.  Basically at -1, so 10 units of wear would be at the 9th mark.    

So if you are reading 3.7 against whatever location you decided to read against when NEW, you need to figure that “worn out” is gonna be basically 13.7 or beyond- in other words, past the last line quite a ways.  If you use 5 units of measurement, worn out is at 8.7.  I get the feeling that you somehow think that when you read “5” your barrel will be worn out?  Totally wrong...  when you see 5 units of change, then it might be too worn for competition.  When you get 10 units of movement, then a military armorer might shit can the barrel even if it still shot OK.  

You have seen it go from 3.7 to 4.1 (also I call BS on reading 3.7, 4.1, etc- it is more like 3, 4.  Give me a break- there are no in between hash marks)

But if we assume you are correct: .4 of measurement per 1200 rds.  If we extrapolate that to say a nominal 10 units of measure (13.7 reading), that means you have a barrel life of 30,000 rds- assuming constant wear, and that a movement of 10 units means “worn out”.  Of course neither of those are likely true for barrel wear, but it is as close as we can get.  If we are using the 5 units of measure= worn out, then it is still 15,000 rds to get there.  

Quit using that gage wrong.  Monitor how it shoots, and how much movement you get with the gauge, but you can’t assume that because it it in a SCAR it now is a 3.7-10 gage vs a 0-10 gage.  3.7=0.  

Basically- the measurements don’t mean shit.  If 3.7 is new, see how it is doing at 4.7, 5.7, etc etc.  Let us know how it shoots when it is at 8.7, because that it the number you seem to think equals “worn out”.  The way you are doing math, you are calling a barrel with only 1.3 units of wear as worn out!  

Again- no way you can legit say 3.7 anyhow with that gauge!  If you were saying halves, or quarters, I could let it ride...but geez.  

Basically- seems like kind of normal wear.  Quit freaking out that your barrel is going to wear out based on that gage.

Not addressing the photos, just the gage usage.  

TLDR- that gage is designed to be read in an AR thru the bottom of the upper receiver, SCAR’s are not AR’s, so you need to understand that how it initially lines up is different!

Info from Fulton Armory on throat erosion gauges

^^^

I am here to measure the contamination here after he previouse poster dropped that nuke??