So I started shooting a fun competition series at the local shooting range (think 3-gun without jerseys).   I have a bunch of mixed headstamps and figure if I'm shooting 0-50 yards for most of these stages that there has to be a rifle load equivalent to the pistol guys that shoot reduced loads for cost or recoil.  Besides going just above suggested minimum is there anything I should keep in consideration if I wanted to just put rounds downrange without sorting the brass before prep and loading?

What bullet?

If you're going with something inexpensive like the bulk 55's or the armscor 62's, I would say just keep it mid range.  There's greater danger of
a squib if you are trying to go so light that it just barely cycles the rifle.  

Put some on paper and at least make sure the accuracy is acceptable and have fun!

I load up all my mixed brass into blasting ammo. I worked up the load and checked for accuracy and function.

I ream ALL primer pockets and trim all brass to the same specs. Load with 55g fmjbt.

I would work up a load to just under the middle of the charge range.   Run off at four tenths or so increments to be fast working up.   You can of course fine tune it but hey you're in mixed brass.  (I hate mixed brass for rifle loading BTW).   You should be plenty safe staying under the half way point.

50 yards is extreme any moderate charge of medium short range for a high power rifle. Simply loading ammo that feeds and functions 100% will serve you well.

Bump the fired case shoulders back at least -.003". I use -.004" as my target goal.

Make sure you trim your brass to 1.750".

55 grain bullets loaded with a moderate charge of medium to medium fast burning powder will suffice. My first picks would be:

24.5 grains of H335
23.0 grains of H322

Buy Hornady bullets in bulk. Their FMJ's and 55 grain SP's are both cheap and good, two qualities that rarely coincide in the same sentence. 6000 bullet boxes are around $450.00 +/-. You can do some load development to see what works best (smallest groups) from your rifle, but the above listed loads will work just fine inside 50 yards.

I shoot DMR and RECCE competitions and I actually never sort .223 brass by headstamp.  The demand is typically for a 1-2 MOA shot at best (hardest last year was a head shot at 700Y).  

Mixed brass is virtually all I shoot, and I get sub MOA performance pretty reliably.  

What the mixed brass will do is put an occasional flyer out of MOA in there that you will know isn't you.  By pretty reliably I mean 4 out of 5 or 8 out of 10 will hit the MOA target I am aiming at.  

I argue there's not enough case capacity in a .223 to make that much of a difference compared to say, .308 where it wouldn't even be polite to openly discuss this.  If you can find the middle of the accuracy node, you can tolerate mixed brass.

If you are shooting a .223/5.56 I think you would be "safe" with a lighter load. A good example of this may be my 22gr of WC-844 with 55gr bullet. This load would probably be just fine even in the lowest capacity casing.

That being said: I've seen charts on this forum showing average weight or maybe even average capacity of specific name brand as well as military casings. There are only one or 2 headstamps that fall out of the "normal" range. Personally, I would still weed those out.

Just as a side note: While working up my plinking load with the WC-844 I noticed 2 distinct accuracy nods. One was at 22gr the other around 24 to 24.5gr. Since my typical plinking is never more than 300 yards and typically is 50 to 200 yards I went with the load that used less powder.

Motor

Ok so I loaded conservatively based on Hodgdon's data and quickload. 26gr CFE I think. 55gr hornady FMJ. Primer strikes look deeper than normal but this is also the first batch that I have swaged crimped pockets.



No flattening of the primer which is what I normally see with CCI when the load starts getting hot but deeper than normal strikes.