6ppc Lapua case issue

[bluechip]

My 6ppc (220 Russian) Lapua cases are measuring too short for some reason. I try to trim the length at 1.495 and after measuring the length some are as short as 1.478 with many in the low eighties range. These cases have all been shot a few times. What's up here?

 

[Lee Martin]

Did you trim at all before fire-forming? If so, that'll make it hard to keep final length above 1.490".

-Lee
www.singleactions.com

 

[bluechip]

Did you trim at all before fire-forming? If so, that'll make it hard to keep final length above 1.490".

-Lee
www.singleactions.com

I have never trimmed the cases that are showing up short. I've read the having cases that vary in length over .002-.003 will hurt accuracy, but the mixed length cases I have, up to .015 difference, don't seem to shoot any different. Possibly I may not be at the 'one small hole' grouping at 200 yds that would show the difference in case length irregularity. After five shots I can get one hole grouping, but the hole is about as big as it could be and still be considered one hole.

 

[Wilbur]

There's nothing magic about 1.495. Trim your cases to the shortest length and see if that helps. It probably won't but it might help you think it does. Be sure to keep that chamber neck area clean so when you finally get some cases that form longer the chamber will be still be long enough to accommodate.