The Lee Carbide Factory Crimp Die, true to its name has a carbide ring inside.
The Lee Carbide FCD is simply a lower price point made die, and there's nothing wrong with it.
The Redding GRX system is a higher price point push through size die, and it's very high quality like most Redding dies are. Both will do what you are looking to do, (bulge bust 40) however the Lee Carbide die is MUCH cheaper initial investment.
http://leeprecision.com/reloading-di...tory-crimp-die
The brass colored ring at the bottom of the image is the carbide ring in a Lee Carbide FCD in image above.
The Lee Carbide FCD is normally used in conjunction with a Lee push through sizer kit press insert, or shell holder pusher.
If you reload, you likely already have a Lee push through sizer kit with a shellholder "push rod" that you can use, and would only need to purchase a Lee Carbide FCD (as sugested by Audie...the Oldfart) If not, you can purchase the complete "Bulge Busting kit" from Lee with the pusher, and pick up a Lee Carbide FCD Seperately.
Here's a link to the whole Lee bulge busting kit from Titan Reloading.
Of course the inexpensive Lee Carbide Factory Crimp Die - the heart of the bulge busting unit is sold separately, so you would also need to purchase a Lee Carbide FCD (with the internals removed) to push the 40S&W brass all the way through.
Lee bulge buster kit = $14.99
http://www.titanreloading.com/index....ter_name=bulge
Lee Carbide 40S&W Factory Crimp Die - $17.24
http://www.titanreloading.com/lee-cr...ory-crimp-die-
So your looking at $17.24 for the 40 S&W Carbide FCD and your ready to go, if you already have the shell holder push rod from a Lee push through Lube and Sizing kit.
If you don't already have a pusher you can borrow, pick up the Lee bulge busting kit for an additional $14.99.
Total - $32.23 for both which is still a pretty decent deal.
Conversely, here's a link with a review regarding the use of the Redding G-Rx die system which does the same thing, only at a higher price point.
http://www.gundigest.com/ammunition-..._fixglockbulge
Links below to the Redding G-Rx Push Thru Base Sizing die
http://www.redding-reloading.com/ind...arbide-die-set
http://www.redding-reloading.com/ind...ase-sizing-die
While Redding does not show prices on their website, I happen to have a Redding 2015 catalog and price list in my possession.
Item No. 96150 G-Rx Carbide Sizing Die* = $119.00
Item No. 96040 G-Rx Steel Sizing die* = $56.50
Item No. 96010 Optional Bottle Adapter = $14.90
Item No. 96020 Large 32oz HDPE Bottle = $9.60
* Includes Shellholder Pushrod
Your going to spend at least $119.00 for the Carbide Redding G-Rx sizing die before shipping. You can't even get the Steel G-Rx sizing die (lube required) for the cost of the entire Lee Carbide bulge busting system.
I will say that I do own the Lee Carbide Factory Crimp Die in 40S&W, and for the price it's a bargain for what you intend to use it for.
Redding makes EXCELLENT dies, in my opinion they are the top shelf brand of reloading dies. I absolutely cherish the Redding dies that I own, but in this case I don't think it's worth the extra cash just for a push through sizer/bulge buster application to purchase the more expensive Redding G-Rx Carbide die.
Other opinions may be much different than my own, but there you go.
- Bullwolf