Buckeye45 wrote:Thank you Gutpile for asking that. I keep waiting for someone to review the new Fcd. I realize I may not be quite as "meticulous" as some here in terms of crimping. I'm looking for a serviceable tool to get the job done for hunting purposes.
The challenging part about discussing the FCD is differentiating between when someone is talking about the FCD Mod originally championed by Wildcatter and illustrated in
This Thread, and the Standard Lee FCD, which has been around since long before the 450b was just a concept. The original FCD was an enhancement to whatever style crimp was used in bottleneck calibers. I myself have an FCD for every bottleneck caliber I own. Some times it enhances accuracy. Some times it reduces the velocity SD, but it was just another spin on how to crimp the bullet
at the mouth of the case, if you choose to crimp. Truth be told, a lot of reloaders don't crimp their bottleneck bullets at all. There is enough neck tension from the length of the neck to secure the bullet in the first place.
Fast forward to the 450b. Its almost impossible, nah,
it is impossible to get a reliable amount of neck tension in the 450b to satisfy all but the most casual reloader, without overdoing the taper or even the new mouth FCD and worrying about safely headspacing on that mouth. The problem is mostly relegated to the original form of the 450b rifle, the autoloading AR platform. The taper crimp, while probably the best compromise between adequate neck tension and accuracy, still leave something to be desired. Enter the side crimp (below the mouth).
The physics governing the ability to transfer an effective stab crimp through a brass wall and into a copper bullet is a challenge. If you ever watched someone on a trampoline with a semi-rigid surface, you will have seen the narrow feet on top yielding a more gradual bulge on the bottom of that surface. OK, so at least I noticed it... Anyway, getting the jaw bite of the FCD to propagate through the brass case wall and make the
same imprint on the bullet is next to impossible. The solution that Wildcatter provided and spelled out in the aforementioned thread, was too make the jaw bite narrower. We're talking like a dull tubing cutter wheel narrow. The narrower the bite, the more likely it will transfer a similar bite to the bullet inside. Here's an image of the original bite width and a modded bite width. In reality, the narrower bite in the picture could have stood to be even more narrow:
Now the Lee FCD, regardless of caliber, is designed to deliver that wide, flat crimp right at the case mouth. That's why we modded the original .45-70 FCD (now the 460 S&W) to move that bite further down the case for a side crimp, as well as narrowing the bite width. Here's a look at four stab crimps with the die adjusted to move them wherever you want the crimp to be located. Like with the taper crimp, it is always desirable to plant the stab on top of a bullet's cannelure or in the case of all copper bullets, into one of the driving band grooves. Hence the adjustable depth:
If you want to accomplish a side, stab crimp, you will have to similarly mod the FCD die that came with your LEE 450b die set. That is, unless you just want the crimp to remain by design, at the mouth.
The original Hornady taper crimp doesn't just make the mouth narrower. There is a general taper applied down the case about the length that the bullet is seated. It creates not only a light bite at the mouth, but it shapes a reverse taper on the case for the duration of its contact with the bullet. Kind of like a slight wedge. I doesn't mess much with the heel of the bullet as you don't want the last thing that touches your muzzle to be narrower in diameter. That destabilizes the bullet just when its the most vulnerable.
So always be clear when throwing out the term FCD, to differentiate between a mouth FCD crimp or a side stab FCD crimp, that you're discussing.
Hoot