Diagnose My Crimp

[IowaShooter]

Hello,

I'm a moderately experienced reloader who has never reloaded for a straight wall cartridge before (mostly 308 win, 223 rem, 222 rem, 17 rem, etc) and have been kind of stumped on my first reloads for 450 Bushmaster. I've read multiple times that a taper crimp is necessary as the cartridge headspaces on the rim. I have used my Lee 450 Bushmaster die set to resize, expand, and seat without hiccup, but have ran into a problem on the crimping. My first two rounds I followed directions state by Lee for their factory crimp die:

Screw die to shellholder, 1/2 additional turn, and finger tighten ring.

The first two looked horribly overcrimped to me. Measurements close to the case mouth are around 0.458". I have attached some pictures below.






The next three I did (the first two and these next three are text rounds to get on paper, not for load development) I backed out the die and still looked like too much to me. I measured 0.468" or close to (these were hard tp get a solid reading on as the crimped surface is so small).






So I backed out the die once again and ran another through, barely noticing any crimping effect although I could tell a slight one was applied. I ran the rest of the 20 rounds through in this way just to seat for now until I hear back from you experts. These I measured close to 0.475".






Any advise you may be able to give me would be great. I'm leaning towards pulling the first two, sighting in with the next three, and leaving the last ones alone at this point but want to see everyones opinions on the my first go at taper crimping (which honestly looks more like a weak roll crimp to me), and any pointers to improve my crimping process will be welcome as well.

Thanks for any info from a new poster.

[Hoot]

Link to My Advice

Hoot

[Al in Mi]

thou I haven't used the Lee 450 die yet, I taper crimp my XTP's about .030 below the cannuler. I know others that taper crimp to the edge of the cannuler, theirs look like your last pic.

[IowaShooter]

:shock:

Link to My Advice

Hoot

Thanks Hoot, I was hoping you might see this. I read through the post and look forward to getting home tonight to try this approach out. Based off the info you have in there, my last 20 rds (0.475") should be fine, correct? The other 5 (moderate and heavy crimp) should be pulled I assume?

Thanks again for your help and any information.

[IowaShooter]

thou I haven't used the Lee 450 die yet, I taper crimp my XTP's about .030 below the cannuler. I know others that taper crimp to the edge of the cannuler, theirs look like your last pic.

Good to hear, thank you.

[Hoot]

Assuming your cases are not unusually short, that dies doesn't look like it catches enough of the mouth to do much good. The wider the jaw bite, the more crimped case you have on the bullet and the less constriction you need to achieve the same amount of retention. If your cases aren't unusually short, I'd be dedicating a shell holder (RCBS #3 Hor #1 Lee #5 etc) to just 450b service and shortening it to get more of the case up inside the collet before it activates the jaw closure. I've done just that but not for crimping since I use the Hornady taper crimp. I did it to use with the sizing die to get it to size a little further down the toward the web. That may not be necessary once you adjust your FCD using the technique spelled out in that link.

I can't imagine how one could mis-adjust it to cause such a narrow bite width and still get the collet to engage.



Hoot