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What tool do you use to measure if your case neck is getting too long?

L

Lofty

Gunny Sergeant
Full Member
Minuteman
Jun 14, 2008
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Lenexa KS
I've got a bunch of 6.5 Creedmoor brass that's on its 3rd firing and most of the necks have grown about 10 thou over new brass lengths.

What's the best tool for measuring where I should trim the necks back for my specific chamber without going all the way back to factory lengths?
 
Deleted: Reading comprehension error :(
 
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Check your fired cases by inserting a bullet into the neck. I use a loaded round because the bullet has a handle attached. It should be completely free, no resistance. If the cases start to get to long there's a 45 degree angle at the end of the neck and it will start to crimp the neck. It won't happen in one firing and with experience you will start to see changes in clearance on a few cases as they get longer. Most reamers cut necks about .010" longer than SAAMI specs.
 
The book answer is that you should always trim you brass when it gets to, or is past the trim to length. Most of the time in bolt guns you just need to trim one time after the initial firing. I have a girud trimmer so I trim after each loading.
 
DAVETOOLEY said:
Check your fired cases by inserting a bullet into the neck. I use a loaded round because the bullet has a handle attached. It should be completely free, no resistance. If the cases start to get to long there's a 45 degree angle at the end of the neck and it will start to crimp the neck. It won't happen in one firing and with experience you will start to see changes in clearance on a few cases as they get longer. Most reamers cut necks about .010" longer than SAAMI specs.
Click to expand...

Great info....

Thanks guys.
 
If you get a custom barrel chambered the absolute best way is to get a chamber gage made with the finishing reamer. About a 1"long piece of barrel 5/8- 3/4" in diameter cut with the same reamer to shoulder depth and a narrow window machined to exposed the end of the neck. You can see the clearance between the end of the case and the end of the neck in the chamber, you can use it as a shoulder bump gage and you can use it as a seating depth gage without having to wrestle with your rifle in your loading room. Kind of handy to have around.
 
DAVETOOLEY said:
If you get a custom barrel chambered the absolute best way is to get a chamber gage made with the finishing reamer. About a 1"long piece of barrel 5/8- 3/4" in diameter cut with the same reamer to shoulder depth and a narrow window....... you can use it as a shoulder bump gage and you can use it as a seating depth gage.........
Click to expand...
Mr. Tooley, what a wonderful idea. If you have the time would you provide more detail as to the gauge-wise application. Even just visual confirmation (loupe enhanced) of these parameters would be nice. To the OP, sorry for the misdirect. To Mr. Tooley, as always, thanks for your insights.
Cheers, Pete
 
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