Thread: Tight chamber and marks on projectile

Originally Posted by grandpamac

Greetings,
Looks as though the projectiles are seated too long. The marks are from the rifling. Either the adjustment on your die has moved or if you have just started a new box of projectiles then they are a different shape. This does happen from time to time and the seating depth needs to be adjusted to suit. If it is a compressed charge then your projectiles may have crept forward.
Regards Grandpamac.

grandpamac has identified the issue. The COAL is too long as pics 1 and 3 show rifling marks on the bullet. Looks like the bullets were pushed a fair way into the rifling when chambered. As gpm says when changing to a new pack of bullets, supposedly even the exact same profile and weight, there can be subtle changes that sometimes allows bullets contact the lands and you need to adjust the COAL to prevent jamming bullets. I have found this mostly happening with Hornady bullets. Other makes, not so much.
Another possibility ( recently discussed here on another thread ), but I don't think is the case here yet, is if you neck size only it eventually leads to case lengthening to the point that rounds become tight on chambering. You will then need to FL size the brass to return to easy chambering and a perfect chamber fit.
Finding bullet marking on only one side can be due to the extractor holding the bullet slightly off centre line as it's chambered, or due to a bolt face not perpendicular to the boreline causing the same thing. Or it may just be the chamber throat ( leade ) that is cut unevenly meaning one side of the bullet contact lands before the remaining surface. This is not uncommon in non custom rifles. But obviously your rifle shoots very nicely so no point in worrying about any of this. Get the COAL sorted as gpm says and you should be back to business as usual.