Done Trimming Brass!

I'm SOL on my AI chambers! 🤣 I just got a 243 AI and noticed when I shot in 243AI mode, there was a lot more carbon built up in the throat!
My 243 AI was the same. The forming process caused necks to shorten and the cases never stretched enough to need trimming and a carbon ring was there. Ive only ever trimmed 1 AI case, a 257AI
 
I keep my comp rifle brass .005" off chamber end, all cases are run through the trimmer after a match and sized for the next match.
All of my chamber prints have it listed how much the chamber is longer than the max length of brass, most are .040-.050" longer, good to know on short neck cartridges like the 264WM & 300WM.
MY hunting rifles are kept at .020" from chamber end just because.

Cheers.
 
This is why I make a chamber length gauge for each of my rifles. It allows me to know what my trim length actually needs to be.
I do the same thing. Make them out of aluminum or brass so they don't scratch anything. My 300WM is about .020 longer than the spec'd trim length.
 
This is where trimming 10-20 on a setting, calculating Sd and then using 3 times Sd should get you the max length. Average length plus 3x Sd.
 
I swear you guys are going to cost me money, again. I didn't know I needed a bore scope until this thread. Now a chamber length gage too?

Not to derail the tread, but can a bore scope also see when a bullet is touching the lands?
 
Bore scope is very handy, more for actually, well inspecting the bore... I doubt you will be able to see if bullet is toughing the lands with one unless you cut off bullet ogive, but that's easy to measure other ways.

Chamber length guage is simple to make with a sacrificial piece of brass.

 
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