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Throat Erosion Question.

I have a 700 that I have shot since 2013 and has 2-3,000 rounds through it (about- I haven't been diligent about round counts). I haven't been able to get it to shoot well this year and was wondering if the barrel is done for. I'll get one or two sub 1/2moa shots, then a flier 1+moa.

Checking old load sheets and how I'm loading the same bullet today ( Lapua 167gr Scenar) there is a difference of .077" in bolt face to ogive. The ogive is, naturally, further out now.

My question is; is the .077" enough to say it's time to re-barrel, or is this normal? I have heard 308's have a long barrel life, but I could use some input from others.

Thanks in advance.
 
I have a 700 that I have shot since 2013 and has 2-3,000 rounds through it (about- I haven't been diligent about round counts). I haven't been able to get it to shoot well this year and was wondering if the barrel is done for. I'll get one or two sub 1/2moa shots, then a flier 1+moa.

Checking old load sheets and how I'm loading the same bullet today ( Lapua 167gr Scenar) there is a difference of .077" in bolt face to ogive. The ogive is, naturally, further out now.

My question is; is the .077" enough to say it's time to re-barrel, or is this normal? I have heard 308's have a long barrel life, but I could use some input from others.

Thanks in advance.
Not that your case mirrors mine but I have well over 5000 rounds on one of my 308 barrels. Amazingly it's a factory barrel and still shoots around .5-.75 moa. I ran it pretty hard at first pushing 185s over 2750 fps. After and since, it's been 168s at 2800 fps. Never measured throat wear as I don't chase the lands. I load for around 2.9 and leave that coal as is. I'd say clean that throat area thoroughly and use that Teslong borescope and see how it shoots. That borescope will be a very effective tool in your cleaning arsenal.
 
I saw some YouTube videos of the Teslong unit. Looks good - I like that it connects to computer so you can really see the images.

I think the first step will be to scrub the throat & barrel - make sure that's good. While I'm waiting on the Teslong...the cost of that will pay for itself pretty quick in ammo not wasted trying to figure out what's what.

Thanks for all the good input, guys. I do appreciate it.
 
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I saw some YouTube videos of the Teslong unit. Looks good - I like that it connects to computer so you can really see the images.

I think the first step will be to scrub the throat & barrel - make sure that's good. While I'm waiting on the Teslong...the cost of that will pay for itself pretty quick in ammo not wasted trying to figure out what's what.

Thanks for all the good input, guys. I do appreciate it.
I love mine. I connect to my cellular device( Android) so at the range when cleaning, I can see where I need to concentrate the most. Just a convenience really. I can use it with my tablet or computer also.
 
I saw some YouTube videos of the Teslong unit. Looks good - I like that it connects to computer so you can really see the images.

I think the first step will be to scrub the throat & barrel - make sure that's good. While I'm waiting on the Teslong...the cost of that will pay for itself pretty quick in ammo not wasted trying to figure out what's what.

Thanks for all the good input, guys. I do appreciate it.

Yep, the barrel looks shiny and clear to the eye but the scope will probably show the throat is erroded, cracked, and loaded with carbon. At this stage a lot of brushing will be required to clean it; afterwards reoptimize seating depth and powder. Then you will know.
 
What load have you been running with the 167s? The reason I ask is that 0.077" seems like a LOT of throat erosion. I typically see well under 0.010" erosion per 1000 rounds in my .308s, which are all wear Bartlein barrels, so I wouldn't expect to see anywhere close to 0.077" erosion after 3000 rounds. If you're running the factory barrel, that might account for some of the difference; different barrel, different steel. Nonetheless, I'll also ask how certain you are of the accuracy of that measurement? Any discrepancy in the distance to "touching" measurement could put your seating depth way off from what it was, or what the rifle actually wants.

The suggestion of purchasing one of the Teslong borescopes for about $50 is a good one, particularly in this circumstance. Carbon buildup, or some other issue that you can't visualize without a borescope might be affecting the measurement. Just be aware that purchasing a new borescope can sometimes result in what I like to call "Borescope Anxiety Disorder", or BAD. Those that haven't looked at their barrels routinely sometimes become distressed over every little fire-crack, pit, or other anomaly they might see when they start using their new borescope. If you decide to buy one, I would suggest starting with the "big" picture first. Is there a lot of fouling in the throat? Is there a sizable carbon ring, which typically looks pretty much exactly like the name indicates, either between the edge of the case mouth and the end of the chamber, or slightly into the rifling/bore just ahead of where the bullet ogive would be situated? Is there a substantial buildup of copper, especially in the last inch or two of bore near the muzzle? You will certainly see a lot of fire-cracking in a barrel with 3000 rounds; that is normal. Just don't get caught up initially in excessive concern over every tiny nick, scratch, or piece of lint you might see.

The good news is that if you have any serious carbon fouling, that can largely be removed. You can search here to find various methods by which people achieve that goal. Everyone has their favored approach to do this. Severe fire-cracking can also be remedied to some extent. KG-2 bore polish for about 80 strokes in the first few inches of barrel is one approach that can [temporarily] minimize the effect of the fire-cracking and possibly gain you another few hundred rounds before it re-appears. The process is not infinite, it can't simply be repeated every 500 rounds or so to gain an additional several thousand rounds from an old barrel. However, it can often allow a barrel to shoot much better for a finite number of rounds.

As has been suggested, it sounds like your barrel might benefit from some specialized (i.e. above and beyond your normal cleaning regimen) cleaning steps if any of these problems are evident. Frankly, you could probably just already assume those problems exist at that round count and undertake the proper cleaning steps even if you don't purchase a borescope. Then start back with fresh distance to touching measurements, and proceed with load development in an unbiased manner, essentially as though the rifle was new (i.e. don't base the new load development process after cleaning on the previous load parameters).
 
I've got the Teslong scope on order and headed this way.

As far as loads I've used they range from Varget at 40.5gr to H380 at 45.0 (one of the better ones). These aren't real hot loads - hot doesn't equal accuracy, in my experience. This is a bone stock 700 (varmint barrel) except for the Jewell trigger.

Barrel replacement looks to be the way to go. I've looking at some Remage conversions and think that might be good project.
 
I have a 700 that I have shot since 2013 and has 2-3,000 rounds through it (about- I haven't been diligent about round counts). I haven't been able to get it to shoot well this year and was wondering if the barrel is done for. I'll get one or two sub 1/2moa shots, then a flier 1+moa.

Checking old load sheets and how I'm loading the same bullet today ( Lapua 167gr Scenar) there is a difference of .077" in bolt face to ogive. The ogive is, naturally, further out now.

My question is; is the .077" enough to say it's time to re-barrel, or is this normal? I have heard 308's have a long barrel life, but I could use some input from others.

Thanks in advance.


Before you start making your self crazy, especially with a borescope and replacing barrels that may not necessarily require rebarreling, stop and take a breathe... First, I now several individuals who are approaching 8k on their 308 barrels and still going strong. Do a good cleaning but follow it with a polishing with which ever bore polishing compound floats y'ur bloat. Keep the same load data you've been using and readjust your seating depth with the 167's. Personally, I would start with a .020-.030" jump. I'm not totally familiar with the aspects of a Lapua 167 but if they are anything relative to Sierra 168's this might be a good start. You have to periodically reevaluate your throat erosion and adjust the seating depth accordingly. I don't think your powder charge or primer selection has anything to do with it. If it has been running strong up to this point, I lean toward seating depth change. If seating depth does not work, Then go to the borescope for the signs of remaining carbon rings but the polishing should have removed any traces. Clean it again. Don't let the ugliness of the interior force you to believe the barrel is shot.
There are many possibilities you need to evaluate before anyone who may have a vested interest in barrel mfg or sales suggests you need a new barrel. Then you can determine if your load data needs tweeking or not. One thing I am curious about...Has the static position of the rifle changed at all? Different rest, position, bipod, etc...
 
Lots of good advice here. @coldboreshot was probably spot on with slow down, take a breath, ...not my usual mode of doing things. I have been doing some serious cleaning with brushes, jags, Hoppe's 9, Sweets 7.62, and J B Bore paste. I got a little blue from the Sweets.

I've had it in two different stocks , H-S Precision and Magpul Hunter. Not a significant improvement in either.

I'll put all back together and start from scratch to see where I am now with.
 
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After 3000 rounds how is the glass bedding??? That could very well need redone. How about the trigger?? What is the tested pull weight?? They can change over time.
If it is throat erosion you could check it by seating the bullet out further and see if accuracy improves. If the barrel really shot fantastic at one time and it just has some throat erosion you might want to consider cutting the shoulder back and a re-chamber.
I definitely don't recommend "polishing" any rifle bore. JB Bore Cleaner is not and will not polish, JB Bore Bright is and will. I have never seen anything good or any kind of improvement come from polishing the inside of a bore. If you really want to see how badly it can copper foul just make it like a mirror inside.
I guess the point I am trying to make is that 3000 rounds is a lot, maybe not enough to wash out a 308 Win barrel, but it is enough that there also could be some other things going on that might need to at least be looked at.
 
Bedding on the H-S Precision is good; Magpul no bedding. The trigger is a new Jewell and set at about 1 1/2#. I've tried a RifleBasix trigger and it was gawd-awful creepy, the Jewell is a jewel.
 
When accuracy starts to bleed off, I use Iosso bore paste and it rejuvenates the barrel. I certainly would not do that on every cleaning but my method has worked wonders for me. It has been suggested in other forums that JB's is a bit aggressive. Don't know, don't care. My selected products work successfully for me. I have quite a few barrels with very high round counts in different calibers. I still fall back on my previous input. My money is on adjusting seating depth or another variation based on the new information regarding stocks and triggers.
 
I have a 700 that I have shot since 2013 and has 2-3,000 rounds through it (about- I haven't been diligent about round counts). I haven't been able to get it to shoot well this year and was wondering if the barrel is done for. I'll get one or two sub 1/2moa shots, then a flier 1+moa.

Checking old load sheets and how I'm loading the same bullet today ( Lapua 167gr Scenar) there is a difference of .077" in bolt face to ogive. The ogive is, naturally, further out now.

My question is; is the .077" enough to say it's time to re-barrel, or is this normal? I have heard 308's have a long barrel life, but I could use some input from others.

Thanks in advance.
Are you measuring erosion with the same lot of bullets??
 

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