What's the lowest SD you can get with 223?

[Bob Metcalf]

I have been trying my best to get my SD down in my 223 ammo, but can't seem to get it consistently below 20. It shows up as a fair amount of vertical dispersion on paper even at 100 yards.

I will reference this thread on Sniper's Hide that goes over the many things I have tried:
http://www.scout.com/military/snipe...-is-a-low-sd-obtainable-with-a-factory-barrel

Except now, it is still going on in my new WOA barrel on the AR. I also added neck turning and bullet sorting by length (base to ogive) to that list.

What have you guys been seeing in terms of benchrest quality 223 ammo?

Try using Benchmark over CCI 450's. The grains are much shorter than other powders commonly used in the .223 (Varget is notorious for bridging) and this means more consistent thrown charges. I did a field test with three different calibers and found thrown charges more consistently accurate than weighed. My SD's are consistently single digit in .223 and 6BR.

 

[Bob Metcalf]

I have been trying my best to get my SD down in my 223 ammo, but can't seem to get it consistently below 20. It shows up as a fair amount of vertical dispersion on paper even at 100 yards.

I will reference this thread on Sniper's Hide that goes over the many things I have tried:
http://www.scout.com/military/snipe...-is-a-low-sd-obtainable-with-a-factory-barrel

Except now, it is still going on in my new WOA barrel on the AR. I also added neck turning and bullet sorting by length (base to ogive) to that list.

What have you guys been seeing in terms of benchrest quality 223 ammo?

Forgot to add that neck tension can also make a difference. Anneal after every 3rd or 4th firing. Neck thickness can vary all over the place too in .223 brass, even among same headstamp.

 

[P72]

I like near max charges of IMR 8208 with 68-69 grain bullets. My guess is that pressures generated at near max loads are more uniform. Near max does not mean excessive. I like CCI 450 and Rem 7 1/2 primers.

SD or standard deviation is a statistical measure - be sure you have an adequate sample measured under equal conditions.