When to trim brass

L

Longboat

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Just wondering when guys usually trim their brass. Say 308 for example. Max length is 2.015 and trim length is 2.005.

I trimmed to 2.005 with new brass and after 3 or 4 firings it is getting between say 2.008-2.010 and the odd one hitting 2.012.

Is their any advantage to keeping them all the same length for bullet grip consistency?

Interested to hear what everyone has to say.

I will probobly sicken this reloading forum with questions over the next while. Look out lol....
 
Just get a Lee dead length trimmer for 308 Winchester and trim every third firing.
I usually toss my cases after the 6th firing whether they need it or not.
 
You must trim your brass to keep in between the trim to length and the max length. How often you trim your brass or to what length greatly depends on your goals and your rifle. Some benchrest precision guys will trim to say 2.010 and keep it there. when it grows to 2.011 they will trim. If its under 2.010 they will not use it for precision shooting until it reaches 2.010. all depends how anal you are and how precise you want things to be.

I don't shoot precision rifle per say, I shoot accurately. Personally I am more than happy shooting just at or under sub MOA. I don't have the care, want or time to spend on ensuring everything is absolutely perfect so my grouping is as small as possible. I personally trim all casing to trim length and re-trim every 3 firings. I have never noticed a change in grouping size. The only reason i trim every 3 firings is to ensure my crimp is consistent for semi auto firearms (i don't crimp for bolt action)
 
Get a Sinclair chamber length gauge. On the dozen or so different cartridges/rifles I have measured on, chamber length is around .030" longer than SAAMI max case length
 
I trim every firing.
As using the forster 3in1 (trim/chamfer/debur) i like how a bullet seats in freshly trimmed brass vs untrimmed (because of the deburr i would guess).

And really, with the forster mini lathe trimmer, a power drill, and 2 beers, you can trim big lots in no time.
 
I trim .308 and other rifle rounds to just be consistent for a particular batch, don't really care what it is, just that it's below max and the same.
 
I trim and chamfer after each firing because I wet tumble and the case mouths become slightly peened.

And case growth depends on how much the case expands when fired and how much the case is squeezed smaller during sizing. Example a fat chamber and a skinny die will make the case grow longer faster than a skinny chamber and a fat die. And a small base die will make the cases grow faster than a standard die.

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Below three types of Forster .308 dies and the effects of sizing and case growth.

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Usually after first firing of new brass, I'll set the trimmer at .005 under max and run them all thru, after that I check to see if any that were under have gone over the .005 under max mark and knock them back to .005 under. Unless I am crimping, which I do my level best to avoid, then I want them all +/- .001 at whatever the shortest length is, or at min length. For that I will cull the extra short ones that are under min length, which may occur in that batch.
 
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