Is this pitting or Carbon deposits?

I had a conversation about borescopes with my gunsmith. He said a borescope was often a curse lol. Some of his best guns had barrels that looked like "shxx" when examined with a borescope. Some pitting and machine marks are actually common, if you look in the barrels with a borescope. Borescopes make imperfections look a few hundred times bigger. Maybe very expensive aftermarket barrels have little of those imperfections, but quite common with mass produced factory barrels. My 70 year old Brno shoots sub MOA, but the barrel had machine marks all over the place.
 
Borrescopes are an advantage in that they let you know how well your cleaning process works. Competitive shooters, esp in RF, will clean after a card - 30-ish shots with foul & sighting. A scope gives you a baseline, then you can compare 'appearance' with 'performance' and make adjustments to your cleaning process.
It doesn't necessarily indicate the accuracy of your rifle. My SKS looks like the 'face of the Moon' but shoots 4-MOA, which is v-good for a '51 Tula. My Ruger Ranch x39 has significant 'chatter damage' in a couple spots but still does 1-MOA with Chi-Mil-Surp. And my Sav B22 had RR-tracks when I bought it, that have smoothed out after ca 2K rounds and gets .3-600" @ 50. Every rifle is an individual.
SKS Everywhere
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RANCH x39 - one of 3 spots
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SAV B22 @ Muzzle !
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PS - When I saw the Ruger x39 bore I contacted Gravel Agcy re Warranty, before I shot it at all. If I sent it in at my cost they would 'look at it' and let me know. Likely 3-6-months, so I passed on that and was pleasantly surprised to get MOA accuracy with just a cheap 3-9x40 'package scope' I had. Now has a 6.5-20x50 Vortex and shooting a bit better, esp with Comm ammo. Wish I could afford reloading but equip would cost me way too much at my age.
 
IvoB said:
I use my borescope before and after I clean the barrel - also found it useful looking into fired cases to see the condition of the brass.
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On a similar vein, you can chamber a re-sized case (before you put a primer/powder/bullet into the case) and run the borescope in from the muzzle end, to inspect the case mouth area. Specifically this shows you how much gap between case mouth and chamber mouth, and how that gap compares to your carbon ring buildup in that gap. This can be useful for seeing how critical it is to trim your cases, and how much you can let it grow before it needs trimming.
 
Buck1950 said:
PS - When I saw the Ruger x39 bore I contacted Gravel Agcy re Warranty, before I shot it at all. If I sent it in at my cost they would 'look at it' and let me know.
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I bet the rifle distributors ARE LOVING the proliferation of cheap borescopes into the hands of people who don't understand what they are looking at.




adamg said:
On a similar vein, you can chamber a re-sized case (before you put a primer/powder/bullet into the case) and run the borescope in from the muzzle end, to inspect the case mouth area. Specifically this shows you how much gap between case mouth and chamber mouth, and how that gap compares to your carbon ring buildup in that gap. This can be useful for seeing how critical it is to trim your cases, and how much you can let it grow before it needs trimming.
Click to expand...

You know there is a $5 tool that measures the chamber length.

https://www.brownells.com/reloading/measuring-tools/case-length-gauges/sinclair-chamber-length-gage/
 
Update- I took the RPR out to the range today. I’m happy to report it’s back to shooting in the .4’s again. If not for the 15-20 mph wind today I may have done even better. I also tried a few other seating depths since I had lost 10 thousandths off the lands since the last time I checked- it still shoots best with the same CBTO as I was using before.

If nothing else this borescope has helped improve my cleaning practices.
 
I had a brand new Factory rem. 700 that as a barrel like that. Can be pitting, can be defect in the steel or it happens in the rifling process.
My rifle shot 1 moa still.
 
Pitting may or may not affect accuracy, the only way to tell is shooting. I have seen some really ugly looking rifling shoot amazing groups. The proof is in the target.
 
adamg said:
On a similar vein, you can chamber a re-sized case (before you put a primer/powder/bullet into the case) and run the borescope in from the muzzle end, to inspect the case mouth area. Specifically this shows you how much gap between case mouth and chamber mouth, and how that gap compares to your carbon ring buildup in that gap. This can be useful for seeing how critical it is to trim your cases, and how much you can let it grow before it needs trimming.
Click to expand...

I ran int this by accident when learning to load load paper patch bullets for my 40/65! I was told that you needed a very tight gap ( no more than .002 or so) or paper shearing would happen.
Turned out that almost ALL of my brass was okay for greasers but no good for my PP bullets because it was for lever guns!!
The scope helped me find the length I needed , then I checked the length on my brass after that .
A very wise man once said that bore scopes and chronographs are responsible for selling more barrels than World records! LOL
Cat
 
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