Case Stretch

[Steveu]

All,

I have received my mould from Steve Brooks for my 40-65 and it shoots great, I will right up a post about it later. Right now I have been experiencing .005"-.007" of stretch per firing. I initially loaded some new cases that were formed from starline brass. I have been fireforming this lot of brass with my GG bullets and I get ZERO stretch. I loaded up 8 rounds for a quick test and noticed that all the cases grew .005-.007". I did some research and talked to Kenny Wassaburger and I trimmed the test cases back .002" in case the mouth was grabbing the bullet. More testing showed no improvement. But, on another forum there was a guy having the same issue I have. He used some rosin powder on the cases to see if that would help. I tried it and I found only a few cases stretched to .001". This led me to believe that my chamber is too slick after I had lapped it with some 400 grit and a fired case to alleviate the sticking case issue I had before the PP bullets. So I got some 320 wet/dry and a dowel and by hand I scuffed up the chamber by hand (I don't have a lathe). I loaded 2 cases that were trimmed to my chamber length, that were fired 3 times without annealing, 70 grains of Swiss 1.5fg and my 400 grain DDPP that light finger pressure will seat the bullet in the fired case. The necks were clean and I chamfered them before loading.

Any ideas on what to do?

Cheers,
Steve