Opinions on borescope video requested

[ndking1126]

I've been having some issues with my rifle including poor accuracy, trouble closing the bolt, and most recently ejector marks on the brass. This is a Shilen prefit on a Savage action. With probably 700 or 800 down the tube this is the only time I've ever had problems. I'm shooting factory Hornady Superformance 129 gr SST 260 Rem.

Here's a video of my bore after a decent cleaning:


Reading on the internet leads me to believe I may have a "carbon ring". Any thoughts or advice?

Here's a video of the barrel before I cleaned it if it helps at all:

 

[ndking1126]

A little more detail I meant to add.

I've now tried 3 different lots of ammo and the problem is about the same for all of them.

After cleaning tonight I very easily chambered a round that I couldn't close the bolt on at all prior. The next round I tried wouldn't chamber prior to or after the cleaning.

Prior to cleaning and while at the range, I noticed that on some rounds that wouldn't chamber at all, I could spin the round about 90* with it sitting on my internal magazine and it would chamber normally. To the naked eye, the rounds seemed as round as any other.

 

[Bob Wright]

Yes, I see a bit of powder residue smashed down into the neck. They look like "islands" of powder. It would interest me in getting that material down to the steel in the neck portion of that chamber.
How does a new bullet slide into the neck of a fired pice of brass?

 

[ndking1126]

I don't have a loose bullet to try. Other than buying a puller, is there a way to get one out?

So more cleaning is your recommendation? I think what I found a little weird is how the barrel seems to be darker the closer to the chamber and lighter as it gets closer to the muzzle end. Is that normal? I just got the borescope, so not sure whats normal and what's not.

 

[Bob Wright]

I don't have a loose bullet to try. Other than buying a puller, is there a way to get one out?

So more cleaning is your recommendation? I think what I found a little weird is how the barrel seems to be darker the closer to the chamber and lighter as it gets closer to the muzzle end. Is that normal? I just got the borescope, so not sure whats normal and what's not.

Yes, as the further you go, less powder deposits will be evident, but copper will appear throughout.
So the first 2-3" will be pretty dirty. In your case, powder is accumulating ahead of the brass neck. This area will pile up powder and pinch the release of the neck on firing, driving pressures up randomly.
Pulling a bullet can be done with an RCBS hammer type puller (inertia puller) or a collet puller in a loading press of your choice.
It needs to be looked at to find or eliminate this from contention.
Sounds like you are shooting factory ammo?

 

[ndking1126]

Yes, it's factory ammo. I reloaded for a little while but sold everything when I realized I never have time for it.

OK, I'll see what I can do. May be a couple days, though.

 

[Bob Wright]

Yes, it's factory ammo. I roaded for a little while but sold everything when I realized I never have time for it.

OK, I'll see what I can do. May be a couple days, though.

You need about .004 clearance from a loaded neck to a fireformed neck on spent brass, as a minimum. Most factory rifles will be a bit more than that. Find calipers you can use, and start looking....

 

[Rick Richard]

I see nothing wrong with the condition of your barrel. In fact, it looks much better than some I have seen with the amount of rounds down the tube as you have indicated. Without anymore info, I would begin with case examination first. Pull a bullet, empty the case of powder and see if it will chamber. If not, you may have to resize the cases with the correct "bump back".

 

[ndking1126]

You need about .004 clearance from a loaded neck to a fireformed neck on spent brass, as a minimum. Most factory rifles will be a bit more than that. Find calipers you can use, and start looking....

You mean the neck of the shell needs to be at least .004" bigger after it is fired? I have calipers, so this is an easy one.

 

[ndking1126]

I see nothing wrong with the condition of your barrel. In fact, it looks much better than some I have seen with the amount of rounds down the tube as you have indicated. Without anymore info, I would begin with case examination first. Pull a bullet, empty the case of powder and see if it will chamber. If not, you may have to resize the cases with the correct "bump back".

Thanks Rick. I first suspected cartridge quality control issues on Hornady's part, but after 3 lots of having the same problem, I figured I had to give serious consideration to my barrel.

 

[Bob Wright]

You mean the neck of the shell needs to be at least .004" bigger after it is fired? I have calipers, so this is an easy one.

That's how I do it with custom chambered barrels. .004 is the minimum for good bullet release. Factory offerings may be anywhere.
So, some neck turning would be required if it's less than .004 difference of loaded vs fired brass (not yet resized in a die).
Remember that a new bullet should slip right thru the neck on fired brass, regardless of what you do going forward.

 

[Rick Richard]

Thanks Rick. I first suspected cartridge quality control issues on Hornady's part, but after 3 lots of having the same problem, I figured I had to give serious consideration to my barrel.

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.

 

[Bob Wright]

I looked at your video again. To clarify, it looks like powder buildup is happening not just at the end of the case but blowing back along the neck during shooting. It's not sealing well(?), but do you have dirty brass that you can take pictures of?
And what ammo mfr are you using?
If your brass is dirty all the way up the shoulder, that's the extreme, as that would be a factory brass issue. It should seal where the neck has a light smudge, but not black and certainly not up the shoulder.
Your cleaning regimen is very good.
Edit to add photo:
All these are sealing normally, especiallthe top one that has been annealed, neck turned and fired.

 

[ndking1126]

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 meet. 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.