[B]LAST UPDATE[/B] 16X Mk4 & borescope pics <800 rounds sudden loss of precision

[Wake27]

Yeah if you haven’t tried multiple magnified optics, I would look there first. I’ve had two similar issues, once turned out to be defective chrome lining but I remember the bore scope photos looking very different than yours. The other, I was convinced was a barrel issue but it actually turned out to be a broken optic. I could group sometimes so when I tried to isolate the optic as the issue, it did well enough to pass in my mind. Definitely helped make the case for having more than one magnified optic because diagnosing accuracy issues with an RDS doesn’t go very far.


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[mRad]

Am I seeing this right? A chunk out of the one land? That’s enough to ruin accuracy. If the barrel was made by a reputable company, send them that photo and the barrel back. That’s a no-go barrel.


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[Stickman]

Am I seeing this right? A chunk out of the one land? That’s enough to ruin accuracy. If the barrel was made by a reputable company, send them that photo and the barrel back. That’s a no-go barrel.


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The problem is that it DID shoot good, it actually shot exceptionally well. The larger question is what happened to make it stop firing well, and I would guess getting a chip like that didn't help at all. Especially if its towards the end of the barrel.

[mRad]

The problem is that it DID shoot good, it actually shot exceptionally well. The larger question is what happened to make it stop firing well, and I would guess getting a chip like that didn't help at all. Especially if its towards the end of the barrel.

It would be interesting if we had a picture prior to the inaccuracy problems. There were lots of changes which could have provided an explanation but that type of barrel flaw just can’t be ignored.


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[308sako]

Am I seeing this right? A chunk out of the one land? That’s enough to ruin accuracy. If the barrel was made by a reputable company, send them that photo and the barrel back. That’s a no-go barrel.


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Yes I was rather surprised myself to see that, It is located about 4 inches from the muzzle and can be seen with the naked eye now that the barrel is "clean."

I hope to shoot it tomorrow with a known BIG optic, at least that should rule out that line of inquiry. Also hope to this this level of precision return.



Once again Gentleman I appreciate the feedback.

[Stickman]

It would be interesting if we had a picture prior to the inaccuracy problems. There were lots of changes which could have provided an explanation but that type of barrel flaw just can’t be ignored.

I agree 100%, but it would be a hard stretch to say the gouge (impression) was present during the great accuracy. Which brings us to a barrel which is damaged, not flawed. It may be semantics at this point, but I think of flaw as an issue when the barrel was new, and damaged being sometimes after. This doesn't help the OP either way, I'm just trying to explain my thoughts.

[Stickman]

Yes I was rather surprised myself to see that, It is located about 4 inches from the muzzle and can be seen with the naked eye now that the barrel is "clean."

I hope to shoot it tomorrow with a known BIG optic, at least that should rule out that line of inquiry. Also hope to this this level of precision return.



Once again Gentleman I appreciate the feedback.

Yes please, let us know how it shoots with a clean barrel and known good optic (good magnification). I wish NC would read this one and post his thoughts. Ned knows barrels better than I know cameras.

[sinister]

Interesting occlusion, so other than the lands starting at irregular intervals, and the GP showing normal erosion, the crown passable, the little occlusion in that land... what could happen. Still leaning to trying a better optic and the remaining ammunition previously proven.

Absolutely NOTHING good can come from having that gouge / chunk-hole in your land.

I have no idea how that could have got there. It looks like it has some serious depth. A stray steel pin from wet tumbling, or an old primer anvil or cup would have put in a long, skidding groove vice a pot-hole.

[308sako]

sinister said: "Absolutely NOTHING good can come from having that gouge / chunk-hole in your land."

I have no idea how that could have got there. It looks like it has some serious depth. A stray steel pin from wet tumbling, or an old primer anvil or cup would have put in a long, skidding groove vice a pot-hole.[/QUOTE]

I couldn't agree more. No wet tumbling and as we all can see no skid marks in my undies as yet.

I had a long talk with a dear friend of mine who operates down in Bryan, TX. Bill Wiseman you may know him. The topic was barrel steels and the simple fact is this type of an occlusion could happen simply due to how steel is made. Generally a rare occurrence fortunately, just not rare enough to save me.

Appreciate all the responses and am going to shoot it once more in better conditions when possible.

[sinister]

I had a long talk with a dear friend of mine who operates down in Bryan, TX. Bill Wiseman you may know him. The topic was barrel steels and the simple fact is this type of an occlusion could happen simply due to how steel is made. Generally a rare occurrence fortunately, just not rare enough to save me.

I met Bill when he first moved down here in 1979. Former Olympic Team Armorer and Marine Precision Weapons Shop gunsmith-machinist. He did one of my .45s over 40 years ago, and it's still going strong. His shop's down the road maybe ten minutes.

As a barrel-maker he knows this kind of thing happens occasionally in alloying bar stock before it's even drilled to become a rifle barrel.