hard/grinding when closing bolt

[Schnyd112]

Not a huge problem. I have a .220 swift that I shoot quite often. I was shooting in a silhouette competition this weekend and felt something I have never felt before. After my final 10 shot string (3 min time limit)I had a shoot off. The gun did not have but 10 minutes to cool. When I tried to close the bolt it was pretty hard, took a good amount of force and I could feel grinding. opening was a little sticky, but felt different than just a sticky bolt, like a bolt lug was grinding. When I ejected the case, the case head looked smeared (extractor marks?) The primer was still intact, and cratered correctly, not showing signs of extreme pressure. Closing the bolt without a case I could really feel the grinding. When I got home I took the bolt out and noticed some extra wear on the right lug. I cleaned the chamber and bolt, oiled it up as usual, and it seems the problem is gone. I can chamber rounds just fine.

This is the same load I have been shooting since February, I chrono it pretty regularly to be sure I am still in the same spot and have never had this issue.

Was the chamber too hot and maybe expanded some? I am at a loss here. I load fairly high pressure as it shoots better the faster it goes but have bot run into pressure signs for another .5 grains above my current load. I am at work right now but will take some pictures when I get home.

 

[WildRose]

If it had been a headspace problem created by the heat you'd have probably seen pressure signs on the brass.

There's no way to tell for sure but the most likely answer is that you had some sand/grit or maybe a little piece of brass interfering and removed it with the cleaning.

If the problem pops up again though You may well want to have a gunsmith look at it.

 

[learning]

Sounds like galling to me. A very small amount of copper coat on the lugs is a way to help keep it running smoother. If it continues to gall you will have a head space issue if for no other reason then it will usually wear so much you have to reface your lugs and or lug abutments.

 

[royinidaho]

Either galling or fine dirt.

Similar occurrences happen when, for some reason, kernels of powder get into the lug area.

Stick powders flat lock things up.

Ball powders get ground.

Always slightly lub the rear of the recoil lug. Not the action just the lug. And lightly.

 

[Schnyd112]

Thanks for the replies. I'm not sure what it was, but I have shot it 200+ times since then with no issues. I think it was partially due to necks that were out of spec, partially to some sort of fouling on the bolt. When I took everything apart, cleaned, and lived the problem seemed to disappear. I culled about half of my brass due to inconsistent necks, I will have to turn some of them and see if that helps. It's a factory chamber so I never really thought much about necks, but I have some that measure .016, most are .013. Some of my brass has been shot 8 times.