Help borescope pic analysis

308BAR

308BAR

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Hey to the experienced, experts and gunsmiths if you could lend an ear and maybe provide some thoughts or comments to what is happening with this barrel. Excuse the average photo quality but this was done with a USB bore-scope and no 90* mirror. This is a friend's TRG in a 308Win the picture are of a before and after a cleaning with slip2000. Lots of copper and carbon before cleaning. The chamber cleaned out good and part of the barrel cleaned out did OK as well. After cleaning you can see some copper still but as you get near the last 1/4 toward the crown it's looking real bad. Don't understand why it would be like this near the end of the barrel?? Any ideas? Thoughts and opinion about the condition and life of the barrel.

The barrel has approximately 1600 rounds down the factory barrel threaded muzzle. Loads are moderate mostly shot with 168 and lately Berger 185s.

Thanks in advance.

Chamber before cleaning
before_zpsiloavhnv.jpg


Barrel before cleaning
before2_zpsydr5eqvw.jpg


Chamber After cleaning
image1_zpstkqw50ee.jpg


Barrel After Cleaning
image2_zpsdocnbslj.jpg


1/4 towards the muzzle after cleaning
image4_zpsdnbuwvjh.jpg
 
This is where the bullet is traveling at its fastest velocity before leaving the bore. At this point the jacket is likely getting pretty hot and leaving more material behind.

When this material isn't cleaned out properly, then there can be issues. The issue here is that slight surface flaking has started. After 1600 rounds that's normal.

There are all sorts of reactions between the jacket materia/carbon/chemicals/bbl steel. Allowing the barrels to get very hot can cause this as well when a proper cleaning regimen isn't followed.

Mostly though I would say you are looking at normal wear from burning gasses and friction.

That throat shows a bit of nitrating/erosion as well, also normal for that many rounds.
 
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Well first off you need a real borescope if you want to see anything but you kind of know that I think , barrels burn out in the throat area for a few inches just ahead of the chamber and a 308 with 1600 rounds should still be good for another 1600 or more depending on how competitive you want to be.

It's really hard to tell from the pics but built up copper will only come out with either IOSSO paste or JB bore paste by tight patching it over a nylon brush works good, I've had the opportunity to do a few over the last little while , the pic near the muzzle could be pitting if it's a CM barrel and if bad enough might not shoot well

Copper will build up more on factory barrels in general and once it starts if it isn't removed it just builds up more and gets harder to remove , I expect that barrel is still good and likely needs a good scrubing with the paste it's not likely a 308 barrel is shot out at 1600
 
Another cleaning option is to use Sweet's 7.62. It is an ammoniated cleaner that does an excellent job of removing metal fouling.
1600 rounds through a .308 and it should be nicely broken in - should be good for a lot more shots than that.
 
May one ask, what is the practical effect of copper on the bore?

Assuming there is an equilibrium point beyond which no further copper is deposited (i.e. Vickers barrel at 10000 rds) what is the effect it has on shooting? Presumably it introduces some kind of dispersion, but I'm struggling to envision how.

And how does the variability of a clean/dirty cycle every x rounds compare to that steady-state copper loading?

I can see good reasons for cleaning out the KCl, but the Cu?

Also, on an admittedly unrelated note, I wonder if Doubletap pays extra to have their link right next to the "New Posts" button where my fat thumbs mash it every third time I come here.
 
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Thanks to OP who posted this up for me and all the feedback. Just as a followup here are some better scope pics. This is a 26" factory barrel on a Sako TRG22 in 308 with about 1600 rds. Majority of the barrel appears to be in good shape with well defined lands other than some stubborn copper which I plan to get out with some JB bore paste. Visible heat cracking right at the throat and some signs of heat cracking at where the lands begin, is this normal? Last 4" of the barrel is what worries me as there appears to be signs of pitting and "squiggly" lines. Not sure what that is but guessing corrosion? Very obvious pitting right at the end of the muzzle. Don't know how to interpret the pics whether this is normal to see for this round count, abnormal, or if the barrel might be done. It shoots great at times doing 0.25 min groups, usually holds steady 0.5 min waterline during matches, but have also experienced recent frustration with wild shotgun patterns, fliers, etc but could be due to other variables/me. Any input greatly appreciated.

Throat and start of lands- heat cracking
IMG_0900_zpsuxihszge.jpg

IMG_0903_zpsqmb9d212.jpg


Majority of barrel looks like this
IMG_0898_zpss7c54bxx.jpg

IMG_0899_zpsove4qff9.jpg


Last 4" of barrel towards muzzle
IMG_0893_zpsyqkhcydl.jpg

IMG_0896_zpsu8arnv7e.jpg

IMG_0897_zpsmemdye5d.jpg


Muzzle end of barrel
IMG_0902_zpsxsgpkj81.jpg

IMG_0901_zpsp4plk67q.jpg
 
...and this thread is a good example why 99% of the bore scopes out there are just toys to play with ... money would be better spent on barrels, components, etc.
 
Who cares what it looks like as long as it shoots accurate, keep shooting it and worry once accuracy declines.
 
I am very surprised at the amount of wear given the rd count but, if any barrel is shot with long strings to high temps, damage will occur.

If willing to invest the money:

Chop and recrown that barrel. I would go 2" min. There is alot of damage on the crown and I assume you have not been leaving it soaking in a cup of water :)

What powder are you using?

What bullet?

Maybe be weary of any moisture after your shooting session or how you store your rifle.

The first two pics of the throat/lands are typical but, I would expect to see that level of cracking on a higher rd count barrel BUT hey, every barrel has its own story.

The 4th one down has me curious. The 3rd one down shows a very strong rifling- assume somewhere in the middle of the pipe. The 4th one is almost washed out. Where ever this was taken, go back and review ALL the rifling in this area. If you see a flattening of the lands vs sharp rifling a few inches on either side, measure from the front of the chamber and do tell me what powder/load you are using.

Very interesting stuff.

Jerry
 
One can only think of the utter dismay if one wuzz to pull a spark plug or two and have a gander
down a hole (s)........tee hee...........this could git nasty.
 
Is it OCD? Or does it really make a difference?

I see articles claiming it will hurt accuracy, but those are usually part of a plug for "BobCo Patented Copper Remover". I grow cynical in my old age, so I discount these.

I see statements along the lines of "Copper touching steel in the presence of an electrolyte causes galvanic corrosion." which I'll buy, but in this bone dry part of the world that isn't a big worry for me.

I see self-evidently true statements like "A consistent bore/chamber is one of the things necessary for low dispersion. So expect a freshly scoured barrel to center differently than one that has been shot a few times." But a fully coppered barrel is consistent (more so than a clean one, actually).

I don't see anything along the lines of "Copper in the bore causes dispersion because once there is enough of it the metal spalls off in chunks which stick to every 17th bullet fired and unbalance it." or "Copper in the bore causes an unpredictable friction because it oxidizes rapidly which can change muzzle velocity by up to 200ft/sec over a space of minutes." or some other plausible-sounding mechanism.

Is there some wise person out there who can weigh in on this?

Other than it hurting BobCo's sales, what is bad about leaving copper in the bore?
 
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Mystic Precision said:
I am very surprised at the amount of wear given the rd count but, if any barrel is shot with long strings to high temps, damage will occur.

If willing to invest the money:

Chop and recrown that barrel. I would go 2" min. There is alot of damage on the crown and I assume you have not been leaving it soaking in a cup of water :)

What powder are you using?

What bullet?

Maybe be weary of any moisture after your shooting session or how you store your rifle.

The first two pics of the throat/lands are typical but, I would expect to see that level of cracking on a higher rd count barrel BUT hey, every barrel has its own story.

The 4th one down has me curious. The 3rd one down shows a very strong rifling- assume somewhere in the middle of the pipe. The 4th one is almost washed out. Where ever this was taken, go back and review ALL the rifling in this area. If you see a flattening of the lands vs sharp rifling a few inches on either side, measure from the front of the chamber and do tell me what powder/load you are using.

Very interesting stuff.

Jerry
Click to expand...

The 4th picture down was a closeup of the lands. Shooting 185 juggs with 44.1-44.3 Varget, before 168SMK with IMR4895.
Aside from the scary pics can confirm the barrel won't shoot anymore so it's time to spin it. Talking with some other folks and smiths they weren't surprised even with this round count. The factory TRG barrel was a shooter and was great last season but longevity wasn't there for Fclass use. Things started going downhill fast near the end of the season last year. Perhaps the metallurgy of the barrel was bad but I'm pretty sure I didn't rest it in a cup of water. =p
 
Rayleigh_Scattering said:
what is bad about leaving copper in the bore?
Click to expand...

Assuming the rifle is accurate and the barrel is 'broken in' you need to know your rifle and monitor the accuracy... eventually copper build up will affect accuracy in a negative way.

Until that drop off in accuracy occurs, nothing is bad about leaving copper in the bore...
 
apexi said:
The 4th picture down was a closeup of the lands. Shooting 185 juggs with 44.1-44.3 Varget, before 168SMK with IMR4895.
Aside from the scary pics can confirm the barrel won't shoot anymore so it's time to spin it. Talking with some other folks and smiths they weren't surprised even with this round count. The factory TRG barrel was a shooter and was great last season but longevity wasn't there for Fclass use. Things started going downhill fast near the end of the season last year. Perhaps the metallurgy of the barrel was bad but I'm pretty sure I didn't rest it in a cup of water. =p
Click to expand...
I'm surprised the barrel was competitive for F-Class. Spin a custom one and carry on. :)
 
guntech said:
Assuming the rifle is accurate and the barrel is 'broken in' you need to know your rifle and monitor the accuracy... eventually copper build up will affect accuracy in a negative way.

Until that drop off in accuracy occurs, nothing is bad about leaving copper in the bore...
Click to expand...

There can also be an issue when copper "welds" itself to the bore. When it's left in place and an electrolytic reaction occurs you get the same results the OP has in his pics when it's removed, especially after a long time period. Often the copper itself will turn green which indicates oxidation.

I have seen the same "flaking" finish on barrels that have been overheated with long strings of rapid fire. Depends on the barrel though, some will breeze through such abuse without issues.

I had a Remington 700 in 6mm Rem that had a similar look. It shot well but it was definitely a fouler with the factory barrel. A new barrel corrected the issue. The previous owner of the rifle had used it in a gopher hunt in Montana and put over a thousand rounds through it in one day. He was quite excited when he mentioned how hot the barrel became. He claims to have cleaned it every 30-40 shots and maybe he did but he also mentioned accuracy would fall off quickly after 20 rounds.
 
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