Thread: Same brand cases produce different results for 50 grain vmax in .223

I prepped a bunch of PMC .223 range brass at the same time and did some ladders, found a good load and then made 10 to check for average velocity. 8 rounds were about the same but two had spikes of 100fps as well as one of them did not group like the others of 13/16" at 200yds but was another inch off and up and to the right like it had a pressure spike.

While loading about 250 of these prairie dog rounds I noticed that some the powder was halfway up the neck, a full case, but most were around the shoulder. I started weighing complete rounds and found that about 1/5th were heavier by about 14 grains, the full powder in the neck cases. That would make sense why the velocity change on the two as that would most likely give a pressure spike and make them inconsistent with the rest. I separated them out and now have 200 of the lower weight cases that are about the same as my LC 5.56 cases and the unusually heavy cases will have a different POI with less case volume though the same brand brass and same powder charge.

After separated I looked at the case printing and the heavier cases the PMC letters were real tight together and the lighter cases they were spread apart. Also while prepping the brass and swaging just in case, only some felt like they needed it and my guess is they were the heavier cases. If you have PMC brass you may want to separate them out when loading.

I have found a 22 grain swing in the same brand of .243 cases too, Winchester brand. Two types of lettering, Winchester, and WIN. The spelled out version which I had more of the cases filled about to the shoulder and the WIN filled into the neck some. Most were within 4 grains or so but some way off. That too would explain why I would have occasional flyers.

For me . . . 3% is acceptable. The rest are culled or tossed.
I am fortunate in that before I retired I swooped up a bunch of LC72 MATCH (7.62) and TW73 all same lot # 5.56.
I prepped the 5.56 for my 223Rem's and it is super accurate.
Never heard of a 14gr difference in 223 brass. And PMC is usually great brass from what I have heard. --- SAWMAN