Weird 300 WSM ISSUE

[INTJ]

Every throater i ever saw is turned by hand. The barrel is not removed and you set a depth on it. A pilot runs on a bushing in the barrel and they 're turned by hand. Only takes a few minutes and they really cut easy. In fact you need to be measuring because it is real easy to way overcut the freebore length. I bet there are videos on you tube showing it being done. I believe you are not understanding what hand throating a freebore consists of. Matt

Matt,

The last barrel I chambered was my 300 WSM HG barrel. The reamer has a short throat, so after I cut the chamber I lengthened the throat with my 30 cal throating reamer. This reamer is designed to be used in a lathe and works very well. I think it might allow a better throat because the barrel is still dialed in from the chamber job. I also throated my 300 WSM LG barrel this way.

All that said. I agree that throating, either by hand or in a lathe, wouldn't cause what is described in the original post.

 

[243winxb]

With everything exactly the same, except freebore.

The bullet is still seated deep in the case, longer bullet jump.

Light neck tension/bullet hold, may allow the bullet to move to soon? This may cause a secondary pressure spike?

Add in a std primer, slooow powder and funny things can happen.
https://forum.accurateshooter.com/threads/strange-dent-in-fired-case.4016999/

 

[Steve Blair]

Were temperatures significantly warmer than the first test?