trim to length question

D

deertaker

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So I have a question about the trim to length when you neck size and then what length do you want to trim them to? I have my 300 win and on the head space comparator a new brass measures 2.260 and a fire formed brass measures 2.273. do you take the nominal trim to length and then add 0.013?
Thanks for the help!
 
10 thou under nominal. So 2.62 - .010 = 2.610". That's the standard pat answer.

Here's another answer, since you like guages. Chamber necks are typically extremely over length as a safety feature, and you could likely get a dead cat out in front of the case before it steps down. Measure your chamber, and you can decide on whatever margin you want and get a jump on the other OCD sufferers. ;)
 
I make chamber casts occasionally. Never have I found one that was exactly maximum length. They vary from about .012" long to about .035" long in commercial rifles. [Military rifles tend to be VERY generous in length, lol.]
However, if you have a custom built rifle, that clearance can be as little as .005" over max.

That being said, I trim my brass to max length minus .010", mainly to keep the length equal.
So, as posted by Dogleg, the 300 Win Mag would get trimmed to 2.610", once it reached 2.620" A 30-06 would be trimmed to 2.484", etc, etc. D.
 
Thanks for the help guys, I was surprised to measure the overall length of the brass and it did not change too much from the nominal trim to length, even though the brass was fire formed. I just trimmed it to the recommended length in the manuals.
 
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