Ok for starters, I am completley new to reloading, and own a AR-10a4 with a 20" barrel.
I just picked up the Dillon 550 Basic press, Hornady dies, a brass tumbler, and a powder tube.

I would like some recommendations though.  I know I need a scale,  any better than others out there?  
Also how many of you use a Concentricity Gauge?  

Basically, im happy the press will save some money on ammo costs but I am more interested in seeing if I can tighten up my groups and get some better accuracy or consistency out of my rifle with hand loads, Though because I average 1moa or less now with Hornady 168grn BTHP match and have been happy with its results. I am also not looking to go broke by over buying or buying accessories that I wouldnt need though.

I also have the Hornady reloading manual, and expect that Loads for the M1A / service rifle would be what I would be looking at to get started as they are both not bolt action.

Any suggestions,  preferred loads, do's/ donts, ect would be fantastic.  Thanks in advance


Edit;  I also wanted to point out that I know there is a reloading forum, but I was looking for some advice tailored to the AR10 platform

I just recently bought a concentricity guage, and although i haven't shot any i have fixed yet, i can't believe how out of round factory stuff is, including match ammo!!
I found the best price here:
http://store.superioroutdoorsman.com/catalog/product.asp?ret_id=1085919&pid=66552

Good choice on the press, I have a 550B and love it!  Service rifle loads are to protect the op rod on M1A's.  I run bolt rifle loads through my AR10C4 without issue.  Hodgdon's loading data seems conservative as I've run up to their max loads and not seen pressure signs.  Each rifle is unique though and a max must be worked up to.   I develop for group size but have found my best groups are near max with the powders I've tried so far.  My rifle seems to like IMR4895, RL-15 and IMR 8208XBR for accuracy.  BL(c)-2 was miserable and H335 only slightly better.  A lot of loaders use Varget with excellent results, I just haven't gotten around to trying it yet.  My rifle seems to group 168 Amax's tighter than any 155 gr. bullet I've tried.  A chronograph is a great tool for load development.  I use an RCBS 5-10 scale I've had for 36 yrs., also have an MTM electronic but find the balance scale more consistent.  Set your size die for .002 to .003 shoulder bump.  I've had to reduce my expander diameters to get a .003 neck grip to avoid bullet set back during feeding.  You could also crimp and if you do, the Lee FCD is the way to go.  I've come to prefer the higher neck tension though.  Have fun!

Good info  Thanks

Buy a digital scale.

I use IMR 4895 powder with those Hornady 168gr BTHP's.
Winchester standard large rifle primers.

I get unbelievable accuracy from my Armalite AR10A4, 20 inch barrel.
with that load combination.

Just work up what powder charge you like best.

Also get a good set of digital calipers to measure your brass case lengths
and your cartridge overall length (COL).  These two measurements are critical.

I like the Kobalt calipers from Lowes Hardware.