by BD1 » Wed Jul 21, 2010 8:29 pm
I'm not a commercial ammo manufacturer. My opinions are based solely on my own experience. They are worth just what you paid for them.
It's a little tough to tell from your pics exactly what's going on. However, it looks like your side crimp is much lower, and tighter, than mine. I've been using the Lee FCD dies for .223, 6.5x55, 270 WBY mag and .44 mag for 15 years with excellent success. My goal with the .450B was to achieve the same style of crimp about a tenth of an inch below the case mouth so it didn't effect the case's ability to headspace on the case mouth. So far, in every load, using every bullet I've tried, the modified crimp has given me better velocity, lower SD values and better groups than the Hornady taper crimp die. This is very apparent in cast boolit loads. A properly applied FCD crimp should not damage the jacket, or "wasp waist" the bullet. With good neck tension the crimp needs only to keep the bullet from moving due to the momentum of chambering. There is no need to land on a cannelure, or squash a ring into the jacket. .001" "indent" in the jacket is plenty. Look at a couple of factory bottle necked rounds, .223, 30-06, .270 W. The crimp is very well defined, but very shallow. If you crimp too hard you will bulge the brass out on both sides of the crimp negating the neck tension. This could result in a net loss relative to ignition consistency, rather than an improvement
I pretty much ignore cannelures rolled into jacketed bullets unless they are accurately placed to meet specific OAl requirements, as in the .223 for ARs. The main purpose of cannelures is to help index seating depth in automated loading machinery. IMHO they have little or nothing to do with crimp consistency beyond giving some clearance for roll crimps to use in revolver cartridges.
BD