Project Appleseed

I still don't crimp.
Greatest constancy will be if all brass is the same length. 1.750 is the number I use.

I'm no expert, but no crimp seems to be the norm for high power competitors.

Quote from: desert_diver on June 21, 2020, 07:29:49 PM
I'm getting into reloading and I'd like to get some advice from fellow Appleseeders. 

My immediate goal is to create a couple of long range rounds for my AR-platform rifle with a 20" 1:7 barrel using Sierra 77 gr bullets (#9377T).  The completed round should be able to load from the magazine

Questions:

• To crimp or not to crimp?  I've seen both recommendations in this thread, but it's been a while.  What is the current thinking?  If it matters, the die set I purchased from Redding includes a crimp die.
• Should brass which is less than 1.760" be trimmed?  Most of my brass is 1st firing (my rifle) Federal XM193.  After resizing, most cases are > 1.760".  This brass will definitely get trimmed to 1.750".  I have a limited amount of match-grade Hornady brass, also 1st firing in my rifle.  After resizing, I measured 10 cases; all but one was < 1.760" and that case measured 1.7605". 

Thanks in advance for the advice.

Jon.

I bought a Redding crimp die I'll mess with some day but the only reason to crimp (for me) is to prevent set back in TEOTWAKI ammo.  Since none of the pros crimp match ammo I'll follow their lead.

Consistent head space and keeping cases trimmed to 1.750 means all rounds have the same neck length which helps to keep neck tension/release the same.

If you have to measure brass to see if it needs trimmed you might as well spend that time putting it in the trimmer.  If it doesn't need trimmed it doesn't get touched but any long cases get trimmed.

Since the bullet loaded to magazine length is incredibly popular with high power shooters you'll be able to find a good load easily.

I like adding an inside neck sizing mandrel to my steps to set the neck ID identical on all the rounds for as consistent as possible neck tension.

On trim length since 1.760 is max case length you can be pushing an unsafe condition by leaving your cases just under that (assuming a long one could slip though) if your chamber has a short neck.  Better to follow standard practice and trim to 1.750.

Thanks for the advice!

I will definitely trim all my brass to 1.750". 

Jon