Divots in my grooves

[fxdrider]

So I bought this new bore-scope...

And I found at least 2 of these little divots/pock-marks in the grooves of my Remington 700 .308. Just curious...anyone seen this before? Seems like it shouldn't be a 'normal' feature of a barrel.
Barrel has just under 1000 rounds through it. What would cause that? I don't know if they affect accuracy much, but they sure don't do much for confidence.

 

[DownhillFromHere]

In my experience with (probably) the same borescope, there is a correlation between barrel price tier/purpose and flaws / machining marks in the bore such as what you see.

I've seen zero such marks in my Bartlein and Vudoo/Ace barrels.

Conversely, I put the scope in the barrel of a well-respected AR manufacturer's SS barrel mounted on a $1500 rifle, which holds consistent sub-MOA groups with match ammo. I was astounded at the cuts, chatter marks, and gouges. The rifle is built and marketed as a high-quality 3-gun/CQB/patrol platform, not a match rifle. Yet, it shoots doggone near match-rifle groups, despite the comparatively chewed-looking bore.

So, I can comfortably say from experience - if your rifle is accurate, or isn't, that little divot has nothing to do with it.

 

[Steel head]

So I bought this new bore-scope...

And I found at least 2 of these little divots/pock-marks in the grooves of my Remington 700 .308. Just curious...anyone seen this before? Seems like it shouldn't be a 'normal' feature of a barrel.
Barrel has just under 1000 rounds through it. What would cause that? I don't know if they affect accuracy much, but they sure don't do much for confidence.

View attachment 7721138

Go take a look in a good shooting Remington or savage barrel

 

[nn8734]

So I bought this new bore-scope...

Why?
How does the rifle shoot?

 

[celltech]

Obviously this cheap 700 barrel ain't a Bartlein. If it shoots to your expectations then just keep firing away.

 

[Mike Casselton]

What was your confidence level before owning the bore scope?

If it shot well before peeking at it, it'll still shoot the same.

If it shot like shit before, it'll still shoot like shit.

If it suddenly starts shooting like shit after viewing it through the bore scope, then you might need to seek the treatment of a counselor because your mind is weak.

 

[fxdrider]

So, I can comfortably say from experience - if your rifle is accurate, or isn't, that little divot has nothing to do with it.

That's kinda what I figured.

Obviously this cheap 700 barrel ain't a Bartlein. If it shoots to your expectations then just keep firing away.

Yeah, it shoots fine. I was just surprised - had never seen anything like that. The bore-scope shows all...

 

[6.5SH]

I have a Vanguard (Howa) that looks like it was rifled with a rototiller, it still more than met their accuracy guarantee of under 1 MOA.
You'd be surprised how bad stuff can look and still perform.

 

[Shoots 700's]

Thats why i don’t look

 

[ormandj]

If you’re having issues a borescope can help diagnose them. Evaluating your cleaning routine, your borescope can help determine if you’re doing the right thing.

Judging a gunsmith’s attention to detail and machining skills, the borescope will help (mass produced barrels may have chatter due to worn tooling or running at too high a rate for the fixturing or machine, but custom barrels like this are just sloppy work. They may shoot fine, but that doesn’t excuse poor worksmanship).

Looking at a barrel that shoots great and seeing a flaw but not reasoning through potential impact isn’t good, though. A little chip missing out of a land somewhere in the middle of the barrel is unlikely to do a thing. Think about how the bullet is imprinting in the bore, and reason through what that little chip missing might do/not so.

The throat matters, as does the muzzle/crown, but most of what you see in the middle, as long as it’s not a protrusion deforming the bullet, won’t cause any major problems. Tons of copper fouling or major defects can obviously cause an issue, but a little chip is unlikely to be causing any issues.

PS - maybe I’m not seeing properly, but that looks to be a divot in the land, not groove. I also see a little deformation of the edge of the land. What do you use when cleaning? It’s more likely to be a manufacturing defect, but a steel cleaning rod or cleaning tool can do a number. It looks like something skipped there, or there was debris in the tool path.

 

[The_engineer]

If you look close enough you can find an imperfection in every item you own.

 

[Ridge_Walker]

So I bought this new bore-scope...

And I found at least 2 of these little divots/pock-marks in the grooves of my Remington 700 .308. Just curious...anyone seen this before? Seems like it shouldn't be a 'normal' feature of a barrel.
Barrel has just under 1000 rounds through it. What would cause that? I don't know if they affect accuracy much, but they sure don't do much for confidence.

View attachment 7721138

Yep seen em before. Seen worse in rifles that shoot pretty good. The worst barrel we have with that damage is a Winchester M100 308. It has been rode hard and used wet apparently.

I was told the damage is caused by shooting the rifle with heavy condensation, or rain in the barrel. The theory goes that water is incomressible and the bullet sometimes doesn't displace the water but traps it where it 'explodes' against the steel and can blow a divot in it. I have heard the same re oil in the barrel too.

Read something about this somewhere long ago too. The source I don't recall, but in an article I think. Anyways at the time I thought it was reputable and believable.

I don't know if some steels would be more susceptible, or that this is even true. If so, H2O seems more likely than oil to do it.

Regardless, wether it was made that way (seems unlikely) or not, the M100 shoots pretty good still, even after 59 yrs and many such divots. At least it's still minute of Deer (1.5 MOA) with the right combo, and what I use in the woods. I am keeping an eye out for a better one. Not to use in the woods, just to have. This one is still doing fine for what its used for.

Maybe somebody here knows the truth regarding the theory. I would be interested in knowing the cause for sure. Even though they don't seem to be barrel life ending, not getting them would to be better if possible.

 

[Changed]

Do you reload? Do you timber with SS pins?

 

[srt-4_uk]

I was told the damage is caused by shooting the rifle with heavy condensation, or rain in the barrel. The theory goes that water is incomressible and the bullet sometimes doesn't displace the water but traps it where it 'explodes' against the steel and can blow a divot in it. I have heard the same re oil in the barrel too.

Seems to me that the softer lead/copper bullet would deform before the steel barrel would.

 

[Steel head]

What was your confidence level before owning the bore scope?

If it shot well before peeking at it, it'll still shoot the same.

If it shot like shit before, it'll still shoot like shit.

If it suddenly starts shooting like shit after viewing it through the bore scope, then you might need to seek the treatment of a counselor because your mind is weak.

 

[Ridge_Walker]

Seems to me that the softer lead/copper bullet would deform before the steel barrel would.

It would, you would think. It may, and also damage the steel. I would just like to know for sure. More out of interest in how they get there I guess. My experience is that other defects affect accuracy more than a few pits. Copper, carbon throat erosion etc.

 

[ormandj]

It would, you would think. It may, and also damage the steel. I would just like to know for sure. More out of interest in how they get there I guess. My experience is that other defects affect accuracy more than a few pits. Copper, carbon throat erosion etc.

A small pit in the lands/grooves mid-barrel will have negligible impact on the performance of the barrel. It's not going to deform or disturb the bullet as it travels down the barrel. If there were a raised burr, that would be a different story.

 

[NBPRP]

Bagger Vance here chiming in for Bobby Jones and Walter Hagen.

Me thinks we need more information: Was this your tee shot or were you in the fairway?

If it was the latter then change your grip and choke up on the club shaft a bit.

If it was the former then tee up the ball a little higher.

Also would suggest to keep your head down and follow through like you are 'sweeping the ball' not striking it.

From the looks of it you are using about a 6 or 7 iron if in the fairway and most likely a TaylorMade or Callaway product.





Well.... you threw the bait out there and had to know someone would jump at it.


At any rate, all kidding aside, on a more serious note, none of the previous posts are without merit. They all address poignant aspects regarding what we perceive as 'accuracy' when we shoot at a target be it paper, metallic silhouette, tin cans, milk jugs, etc.

Ridge Walker made a comment that echoes what I heard/read some time ago also, something like the trapped moisture acts almost like a miniature plasma cutter. On a similiar line, but on a much larger scale, prop makers (boats) have to design their product in such a way that they are resistant to the effects of cavitation. The bubbles created by the spinning prop apparently 'explode' in close proximity to the spinning prop and create 'pits' in it. Not the same but food for thought.

Several years ago at a match I was on the periphery of a conversation between Barrett Obermeyer, Mike Rock and John 'Jack' Krieger, who were on the ready line. Earl and Ken Liebetrau were on the firing line, Rudy Wadekamper and Norm Brux were in the pits and I was getting ready to score for Randy Gregory. The conversation between the three drifted in the direction of barrel finish and specifically smoothness of the bore.

Both 'Boots' and 'Jack' acknowledged the importance of minimal tool marks in the drilling and reaming of the hole as well as the rifling, but some degree of imperfections were inevitable. To what degree remains open to debate depending if you are the consumer or the manufacturer.

They did agree on throat erosion being more of a concern as well as some type of defect regarding the muzzle crown. Even went so far as to mention one shooter (no-one I was acquainted with) actually had his 26" barrel rechambered and had it 'set back' a bit to get rid of the throat erosion. This apparently worked to some extent as that shooter went on to shoot respectfully at Camp Perry that year

Mike said something like 'the bullet shouldn't have to travel the distance of the Verrazano-Narrows bridge to engage the lands' to which elicited a belly laugh from both 'Boots' and 'Jack'.

Well on to the back nine.

 

[Ridge_Walker]

A small pit in the lands/grooves mid-barrel will have negligible impact on the performance of the barrel. It's not going to deform or disturb the bullet as it travels down the barrel. If there were a raised burr, that would be a different story.

Yep we all agree with that. I am wanting to 'know' why the pits appear over time. The root and or stacked cause(s).

 

[Ridge_Walker]

Bagger Vance here chiming in for Bobby Jones and Walter Hagen.

Me thinks we need more information: Was this your tee shot or were you in the fairway?

If it was the latter then change your grip and choke up on the club shaft a bit.

If it was the former then tee up the ball a little higher.

Also would suggest to keep your head down and follow through like you are 'sweeping the ball' not striking it.

From the looks of it you are using about a 6 or 7 iron if in the fairway and most likely a TaylorMade or Callaway product.





Well.... you threw the bait out there and had to know someone would jump at it.


At any rate, all kidding aside, on a more serious note, none of the previous posts are without merit. They all address poignant aspects regarding what we perceive as 'accuracy' when we shoot at a target be it paper, metallic silhouette, tin cans, milk jugs, etc.

Ridge Walker made a comment that echoes what I heard/read some time ago also, something like the trapped moisture acts almost like a miniature plasma cutter. On a similiar line, but on a much larger scale, prop makers (boats) have to design their product in such a way that they are resistant to the effects of cavitation. The bubbles created by the spinning prop apparently 'explode' in close proximity to the spinning prop and create 'pits' in it. Not the same but food for thought.

Several years ago at a match I was on the periphery of a conversation between Barrett Obermeyer, Mike Rock and John 'Jack' Krieger, who were on the ready line. Earl and Ken Liebetrau were on the firing line, Rudy Wadekamper and Norm Brux were in the pits and I was getting ready to score for Randy Gregory. The conversation between the three drifted in the direction of barrel finish and specifically smoothness of the bore.

Both 'Boots' and 'Jack' acknowledged the importance of minimal tool marks in the drilling and reaming of the hole as well as the rifling, but some degree of imperfections were inevitable. To what degree remains open to debate depending if you are the consumer or the manufacturer.

They did agree on throat erosion being more of a concern as well as some type of defect regarding the muzzle crown. Even went so far as to mention one shooter (no-one I was acquainted with) actually had his 26" barrel rechambered and had it 'set back' a bit to get rid of the throat erosion. This apparently worked to some extent as that shooter went on to shoot respectfully at Camp Perry that year

Mike said something like 'the bullet shouldn't have to travel the distance of the Verrazano-Narrows bridge to engage the lands' to which elicited a belly laugh from both 'Boots' and 'Jack'.

Well on to the back nine.

Good point about propeller cavitation. Tends to reinforce the theory. If this was a huge problem I think we all would know the answer.

Re the bullet getting damaged too; ever have bullet disappear, never hit the target? Or you even know it came apart, or just disintegrated and wonder WTF?

 

[NBPRP]

Ridge_Walker,

I, myself have not experienced a bullet that didn't hit the target or disappear during a match, though I did miss the target, low and in the dirt at Camp Perry shooting The Wimbledon. It was my first sighter and the second sighter caught paper but low, scoring only a 7.

I do remember a match at Faribault/Northfield MN in which a shooter a couple of firing points to my right was shooting a .223 which I think was a bolt gun not an AR-15. Every couple of rounds he would fire then wait a while and call for 'a mark' and have his target pulled. Low and behold there would be a bullet hole high up in the target between the 11 and 1 o'clock position. On those shots I would see through my spotting scope what looked like a smoke trail along the path of the bullet and didn't think much of it.

The people in the pit were perplexed so kept the target and after the match removed the pasters over the holes and showed the guy. Each of the holes had a grey smudge that fanned out and dissipated maybe about 1/2 " long and they looked like miniature comet tails in the way they arced.

Several shooters spoke with the person and found out he was a hand loader and prior to the match ran out of his usual bullet so picked up some type of 'varmint or 'blitz' bullet. Not having the time to work up a load he just stuffed a bunch or powder in the case and scrunched a bullet on top.

After some rudimentary 'G2ing' it was though the load was too hot for the thin jacket of the bullet and either heated it up or it was smeared in the lands which compromised the jacket. The hot lead core was then free to escape the jacket creating a 'smoke trail' and painting a comet signature on the target.

 

[Ledzep]

Most likely from a cleaning rod caused the single ding. The black stuff is either carbon or pitting from (very light) corrosion.

Your lands are presumably .003-.004" tall. That divot is well less than .001" deep. The effect on the bullet will be an extra subtle scratch mark down the bearing surface of a bullet... And whatever you stir up in your head.

 

[308pirate]

So I bought this new bore-scope...

Good now throw it away.

 

[TheGerman]

Anti Coriolis pockets.

 

[Ridge_Walker]

Ridge_Walker,

I, myself have not experienced a bullet that didn't hit the target or disappear during a match, though I did miss the target, low and in the dirt at Camp Perry shooting The Wimbledon. It was my first sighter and the second sighter caught paper but low, scoring only a 7.

I do remember a match at Faribault/Northfield MN in which a shooter a couple of firing points to my right was shooting a .223 which I think was a bolt gun not an AR-15. Every couple of rounds he would fire then wait a while and call for 'a mark' and have his target pulled. Low and behold there would be a bullet hole high up in the target between the 11 and 1 o'clock position. On those shots I would see through my spotting scope what looked like a smoke trail along the path of the bullet and didn't think much of it.

The people in the pit were perplexed so kept the target and after the match removed the pasters over the holes and showed the guy. Each of the holes had a grey smudge that fanned out and dissipated maybe about 1/2 long and they looked like miniature comet tails in the way they arced.

Several shooters spoke with the person and found out he was a hand loader and prior to the match ran out of his usual bullet so picked up some type of 'varmint or 'blitz' bullet. Not having the time to work up a load he just stuffed a bunch or powder in the case and scrunched a bullet on top.

After some rudimentary 'G2ing' it was though the load was too hot for the thin jacket of the bullet and either heated it up or it was smeared in the lands which compromised the jacket. The hot lead core was then free to escape the jacket creating a 'smoke trail' and painting a comet signature on the target.

I haven't had one vanish. If I don't have a hit I am sure I've missed, not experienced a 'vanishing' bullet. I have heard of it and remain skeptical. I have had two that have come apart. Targets told the story both times, and both times it was multiple targets that reicieved the shrapnel.

 

[Ridge_Walker]

Most likely from a cleaning rod caused the single ding. The black stuff is either carbon or pitting from (very light) corrosion.

Your lands are presumably .003-.004" tall. That divot is well less than .001" deep. The effect on the bullet will be an extra subtle scratch mark down the bearing surface of a bullet... And whatever you stir up in your head.

Cleaning Rod? That is one tough cleaning!

 

[Ledzep]

Yeah you'd be surprised. Something as simple as un-sticking a stuck patch can easily ding the bore.

 

[Ridge_Walker]

Yeah you'd be surprised. Something as simple as un-sticking a stuck patch can easily ding the bore.

I'll take your word on it, but I don't put steel in my barrels. Others may use steel cleaning equipment, and it maybe the cause of some damage in barrels. Not sure that it would look like that though, but maybe so.

Pretty sure very few folks are using steel cleaning tools these days. I doubt that nylon, aluminum, brass, or carbon fiber are able to put a divot in rifle steel, but I'm willing to have it explained and admit I am wrong if it is possible. It seems unlikely, but hey I'm always willing to learn.

Once again I don't think that a few divots are an issue re accuracy, I was just honestly hoping to learn of their origin as I have seen them before too.

 

[pabrousseau]

Inclusions in the steel. Impurities that sometimes won't be seen in a new barrel but can burn out with shooting. Seen it in befor steel sako barrel and my rem 700 221.could not see it in the 700 until I'd shot it I don't know how many times.it still shoots in the. 3s.

 

[pabrousseau]

My bartlien, crieger hart and Broughton barrels don't seem to have any.

 

[AccuSol-ERN]

If factory Remmy barrels are still hammer forged I would say this divot was always present and you are just now seeing it. It's very easy to miss (or re-find) little spots with a borescope.

As for the forming of the divot.....in mass production I could totally see a shaving or trash get stuck in the bore or on the mandrel and then formed around.

Ern

 

[fxdrider]

Anti Coriolis pockets.

I like it!

 

[fxdrider]

... I would say this divot was always present and you are just now seeing it. It's very easy to miss (or re-find) little spots with a borescope.

I don't doubt it. They could very well have been there when the rifle was first unboxed back in 2013, and I'm just seeing them now. Looking down the bore with the naked eye, it looks perfect. But run that borescope through and it looks more like the surface of the moon (I exaggerate...a little)

 

[B4Maz]

If you look close enough you can find an imperfection in every item you own.

My wife will disagree

 

[Tokay444]

TLDR.
Ever use Redding dry neck lube with ceramic bead media?

 

[1moaoff]

That's how the barrel gets balanced internally!

 

[Baron23]

TLDR.
Ever use Redding dry neck lube with ceramic bead media?

You lost me here, brother....how is that related to the "divot" in his barrel?

 

[spife7980]

You lost me here, brother....how is that related to the "divot" in his barrel?

One of those beads gets stuck to the other lube (which is why I quit the beads myself) and then you end up with a ceramic ball getting sandwiched by a bullet somehow down the road.

Improbable but not impossible.

 

[Tokay444]

I divotted a barrel exactly this way. To add insult to injury, I probably could have caught when the round before hand hang fired by a fraction of a second. JUST enough to tell me something was different. That bead was in the flash hole, and behind the bullet. The NEXT bullet did the damage, and I should have stopped after the hang fire. Live and learn. Shot my best group out of that barrel AFTER that incident mind you, but it seemed unpredictable.

 

[BOLTRIPPER]

I once owned a Grendel rifle in .308 w/underfolder stock....was made for the police market in the late 70's I think, when i got my first bore scope I just about lost it because the barrel looked like a plowed potato field......BUT I could and did print an inch at 500 yard with handloads consistently.

 

[Greg Langelius *]

First time my Shooting Buddy and I were able to borrow a Hawkeye, we were astounded at what was lurking inside our bores.

A big part of it was that we were not shooting anything like premium barrels.

But the point was, some of the worst looking ones were shooting the best. I flatly could not comprehend how my beautiful Garand could have such ghastly cross cuts and gouges inside and still shoot like an N/M gun, using basic M-2 spec handloads. But it did, and does.

I think we were discounting the benefits of good load development, and also missing some very basic machining facts as they apply to barrel interiors.

Now I have my own inexpensive borescope and use it frequently, but I now accept that most barrel makers' QC is good enough. It may not look so hot, but what I'm seeing and cringing about is apparently not that much of a detriment to actual accuracy as I had once believed.

It renewed my admonition to look at my target, Stupid; and don't sweat the stuff I'd need to be a professional to understand in the first place.

I shoot well when I do my part, and critiquing barrel machining is not part of that job.

Greg

 

[JohnCarter17]

If you look close enough you can find an imperfection in every item you own.

And more in the mirror

 

[Greg Langelius *]

Got me there...

 

[moosemeat]

Moisture in barrel. Oil or water and bullet hydroformed it into the steel.

 

[Ridge_Walker]

Ok now there are a few possibilities on the table. Here they are in the order they appeared:

1. Inclusions, and a witness. This seems like a rational possibility. If this is the answer we have some really crappy steel being used for rifle barrels. Do the premium makers get divots in theirs? Wouldn't Magetic Particle Inspection testing find these?

Inclusions in the steel. Impurities that sometimes won't be seen in a new barrel but can burn out with shooting. Seen it in befor steel sako barrel and my rem 700 221.could not see it in the 700 until I'd shot it I don't know how many times.it still shoots in the. 3s.

2. We go from trash steel to 'Trash on the mandrel'. Again seems reasonable. But some barrels must have had some really filthy mandrels to get multiple divots.

As for the forming of the divot.....in mass production I could totally see a shaving or trash get stuck in the bore or on the mandrel and then formed around.

3. Next is the ceramic ball from cleaning media blown into the bore and pinched by the next bullet. Again we have a witness. Yet seems unlikely to be the cause of all of them. OP fxdrider hasn't said if he used ceramic beads.

and then you end up with a ceramic ball getting sandwiched by a bullet somehow down the road.

4. Now we have a name to give to the wet bore-incompressable liquid theory, 'Hydroforming'. Sounds good, but no references. Can't find much on it any where. Which of course is the reason I asked.

Moisture in barrel. Oil or water and bullet hydroformed it into the steel.

Not saying the 'hydroforming' is impossible, just highly unlikely. What actually would that process be I wonder. Water turning to steam is pretty powerful, and theoretically its crazy powerful, but powerful enough to melt metal?

 

[fxdrider]

OP fxdrider hasn't said if he used ceramic beads.

Nope. No ceramic beads. I use a vibratory cleaner(Dillon) with corncob media - BEFORE I deprime. Most foreign matter that could get caught in the flash-hole is likely poked out by the decapping pin.

 

[AccuSol-ERN]

I think "hydroforming" displaces metal......so it would go somewhere. Maybe a minor bump on the barrel exterior? Maybe cratering around the divot that gets eroded away with multiple firings".

Regardless of the cause....shoot it until it doesn't shoot, then rebarrel. If it happens on the new barrel......re-evaluate ALL your current methods

 

[...]

take your bore scope......and throw it in the fucking trash.

for 99.99% of shooters, they are fucking useless.

if you have a good shooting barrel, how the lands and grooves look doesnt matter.

if you dont have a good shooting barrel, nothing you can see with a bore scope is going to make it shoot any better.....that one bit of copper fouling isnt fucking up your groups.....that one bit of carbon isnt fucking up your groups...


people see a small imperfection in the bore and think that is the cause of all their issues......its not.

 

[moosemeat]

The hydroforming theory is just a theory. I would assume that a bullet hitting a small droplet of water would more than likely deform the projectile, but if it somehow didnt it would most likely make a tear drop shaped divot as the water moved forward of the bullet ever slow slightly. More than likely the water of fluid would be pushed out of the barrel ahead of the bullet by the pressure of the air infront of the bullet.
I'll agree with if it shoots, just shoot it.
I mostly just heard about it from a benchrest shooter. I have hydro formed parts in the past, and seen some accidentally when I build liquid storage tanks. Fill em to fast and they bulge, drain em to fast and the soda can...

 

[swamper2]

take your bore scope......and throw it in the fucking trash.

for 99.99% of shooters, they are fucking useless.

if you have a good shooting barrel, how the lands and grooves look doesnt matter.

if you dont have a good shooting barrel, nothing you can see with a bore scope is going to make it shoot any better.....that one bit of copper fouling isnt fucking up your groups.....that one bit of carbon isnt fucking up your groups...


people see a small imperfection in the bore and think that is the cause of all their issues......its not.

With my bore scope I found the reason that a 22-250 sporter barrel was not grouping for shit was that the last 1 1/4 inch of the muzzel end was burnt out. Zero lands and rough as hell. I cut off 1 1/2 and brought it back in. I like my bore scope