Opinions on borescope video requested

[ndking1126]

I would also try a different make of ammo before I would go further. Hornady anything is not to be trusted in my opinion, but that is just my experience.

Problem is not many 260 loads for precision. It's mostly hunting ammo. Prior to these boxes, they have shot exceptionally well, especially when the ambient temp gets up above 75, 80 degrees.

 

[Bob Wright]

Looks pretty normal for boxed ammo. Your neck expansion is also good. There is some leakage/soot that could be improved by turning but, it's not something to worry about if your not reloading or just getting into it.
I guess I would try unfired loaded ammo marking up the bullet, neck and shoulder with a sharpie
and slip them into the chamber and closing the bolt. Extract it, and look for unusual patterns of ink removal. Like 360° rings at the shoulder/neck, the end of the neck if crimped or on the bullet if it's jamming into the lands.
If you have spent brass that won't feed, clean the necks, ink those up on end of neck, neck o.d. and shoulder, slow feed those in. Inspect.
Also a Smith could look at it if you're not seeing patterns develop.

 

[PddPdd]

Unfired outside diameter at top of neck was .2905-.2910 and fired it was .2960-.2965, so looks good on expansion being more than .004".

Necks were kind of all over the place. The one in the middle was the lowest I found, and it ended right where the neck and shoulders meat. All the rest looked something like the other two or like the cases in your picture. The carbon didn't go as low the shoulder on any but that one piece.

When looking at a close up of your picture of the 3 fired cases it appears that the tip of the neck might not have been outside chamfered or the brass was contacting the end of the chamber relief for the brass when loaded but the picture is kind of grainy. Is there a external lip at the end of the brass when checked with a fingernail?

Might want to check the case length against a SAAMI spec. for length too.

 

[Bob Wright]

Here are some brass numbers. Measure your brass length to the 2.036 value. Where are you at?

 

[LaHunter]

Is that not a carbon ring in the video at :05 ? It appears to be a defined black ring at the end of the neck area. Could just be the lighting / shadow, but it looks like a well defined carbon ring to me.

 

[ndking1126]

When looking at a close up of your picture of the 3 fired cases it appears that the tip of the neck might not have been outside chamfered or the brass was contacting the end of the chamber relief for the brass when loaded but the picture is kind of grainy. Is there a external lip at the end of the brass when checked with a fingernail?

Yes, there is a lip at the neck opening that my fingernail can get caught on. I checked fired and unfired and both have it. Well, they have it to different degrees and some are worse than others. Here's another pic that might be better. You can see the lip on some places but other places didn't have it.

I'll try to sharpie and measure tomorrow.. I just didn't get to it today.

 

[ndking1126]

Is that not a carbon ring in the video at :05 ? It appears to be a defined black ring at the end of the neck area. Could just be the lighting / shadow, but it looks like a well defined carbon ring to me.

I went back and looked at some of the other videos I took and I'm pretty confident that what you are seeing is a shadow.

 

[MNbogboy]

I see carbon in the "neck cut" portion of tje chamber, which is also showing as stains in your fired brass. The carbon often will be the cause of gas leaks resulting in poor chamber seal and will show up in es/sd.
Also your throat area shows built up burnt hard carbon at the beginning of the lands.
I use JB paste or iosso for removing throat carbon. Usually 100-200 strokes with a kroil wash will clean this up nicely.
These bore cameras have significantly changed my cleaning routine. They also have told me that in 60 years I really have never had a clean bore.

 

[ndking1126]

I see carbon in the "neck cut" portion of tje chamber, which is also showing as stains in your fired brass. The carbon often will be the cause of gas leaks resulting in poor chamber seal and will show up in es/sd.
Also your throat area shows built up burnt hard carbon at the beginning of the lands.
I use JB paste or iosso for removing throat carbon. Usually 100-200 strokes with a kroil wash will clean this up nicely.
These bore cameras have significantly changed my cleaning routine. They also have told me that in 60 years I really have never had a clean bore.

Thanks MNbogboy. The hard carbon, as you call it, is what I was wondering about the most. I guess I'll try to pick up one of those you've mentioned. Yeah, this is all very informative to me. Cleaning routines have been more opinion than anything since is was so hard to validate results. I'm glad I bought it.

 

[LaHunter]

I went back and looked at some of the other videos I took and I'm pretty confident that what you are seeing is a shadow.

I would look again. That black ring is exactly where a carbon ring would be, and if you watch closely in the video, there are a few very small specks on the edge of that black ring where the carbon appears to have come off. That should appear as steel, like the other surfaces in your chamber, not black. A carbon ring will absolutely cause difficult bolt closing on a live round, if it builds up enough. A carbon ring can be really tough to remove sometimes, so your previous cleaning attempts may not have done much to remove it

 

[Bob Wright]

Those burrs on the case mouth will provide a leak path to the neck. So did case wall variation I had. Easy to correlate the soot to the varying wall thickness.
If you're buying ammo, you just have to find the ammo that works best. Sloppy factory crimps and poor case chamfers is probably the reason you have those burrs.

 

[MNbogboy]

Thanks MNbogboy. The hard carbon, as you call it, is what I was wondering about the most. I guess I'll try to pick up one of those you've mentioned. Yeah, this is all very informative to me. Cleaning routines have been more opinion than anything since is was so hard to validate results. I'm glad I bought it.

Iosso paste seems to me more aggressive than JB.

 

[MNbogboy]

Here are some pictures of a tool I made for neck carbon. After lengthening a neck on an old 06 case, i cut some slits in the neck and bent then with needle nose pliers until I guessed they would grab/scrape solvent soaked carbon. A rolled up patch stuckintheneck serves to transfer the solvent to the desired area.
When the tool is pushedahead inthe chamber untilitstops the solvetoaked inthe patch is deposited in the target area. I have found thathousehold CLR IS The best solventforhard carbon. Care using CLR around blued parts. It willremove bluingwhichisa formofrust.
Dotask, i found out the hard way.
When i push this tool in I twist it by hand a couple of turns. The case is drilled & tapped through the primer poclet to 1/4-20. The main rod is a brass toilet float rod.

 

[ndking1126]

Thanks everyone for your inputs and ideas. I've got reserves this weekend, so I'm not sure if I'll get to spend much time on it. I'll let you know if I find anything.