6mm Creedmoor chambering issue

[houser52]

I shoot a Ruger American Predator in 6mm Creedmoor and ran into an issue that I haven’t had before. I shoot it regularly and have fired several hundred rounds through it and clean every 100 rounds or so.

I’m shooting Peterson srp brass that has been fired, sized and trimmed, using a less than max load of H4350 and a Hornady 105 bthp at .020” off the lands. My load has been 1/2 moa accurate out to 400 yards.

After swapping scopes and shooting several sight in shots last week, the bolt would not close on the next round. I tried several more rounds and the bolt still would not close. Something was not right so I checked the rest of the rounds for correct head space, case length and COAL, all were in spec.

Since the ammo checked out ok I ran a chamber brush through it and then ran a Bore Tech soaked patch through the bore followed by dry patches. Then tried it and everything chambered and bolt closed as normal.

While shooting it yesterday and after only 4-5 shots the bolt would not close, same problem. Ran the chamber brush through it and now it chambers and the bolt closes like normal.

Not sure what’s going on. The brass has been properly prepped, clean but not polished and bullet seating depth verified. After firing, the brass is not dirty or sooty. It seems to me that after firing, there is something getting into the chamber not allowing the round to fully chamber and running the brush through the chamber removes whatever is in there.

What are your opinions of what’s going on all of a sudden?

 

[ddowning]

It is possible you have a carbon ring. If you have a carbon ring and a chamber that's not clearanced well, it will cause this. I would recommend getting a cheap teslong borescope to assess the situation.

Many people think they are getting a barrel clean, when, in fact, they are not. It takes very aggressive cleaning to get rid of all of the carbon from most typical 6 creed loadings. With the bore scope you can see if you are actually making progress or not.

 

[houser52]

Thanks for the info, I’ll check into it.

 

[8nbait]

Do you shoot with a supressor?

 

[houser52]

No sir I do not shoot with a suppressor.

 

[8nbait]

Ok, thanks, a friend of mine had a similar issue.

 

[Dave Thomas]

Sounds like you have a carbon ring. Do like the other guy said and check it with a borescope.

 

[Jebel]

I agree it sounds like a carbon ring. Once confirmed, you’ll find guidance on how to tackle it by searching. Most recs will include scrubbing the throat and first few inches of the bore with an abrasive cleaner. Like JB bore paste (the bore cleaning compound with the black lid) in a patch wrapped around a jag. If your rifle is prone to this, you’d do well to make this a part of your process every 150 rounds or so.

 

[houser52]

Thanks for all the info.
I don’t have a bore scope yet but I went ahead researched how to remove the carbon ring. Since I already had JB bore paste and everything else to do the job I went ahead and went through the ring removal procedure.

I concentrated on the chamber area with the JB then finished with a thorough cleaning of the chamber and bore with Bore Tech followed by dry patches.

I can’t verify that the ring, if it was there, was completely removed but a lot of black carbon was removed during the chamber cleaning.

I’ll have to get a Teslong ordered in the meantime.

Thanks Again