The LBT 230 WFN mould I have is meant to be used with .41 cal gas checks available from Hornady. They work fine, the sizing die just makes them a bit smaller. .40 cal GC's are also avaible from Gator Gaschecks but I am not sure what they are used on? I know Veral said his moulds are to be used with .41 GC's so that's what I use.
In the pic below L to R is a pulled DT 200 WFN (I think it may be an older style?), the 230 WFN I cast in a LBT mould (no lube in the groove) and then a 200 TC cast in a Lyman mould.
I am still working up loads but at this point I have pushed the 230 WFN (225 grs with hard lead) to 1,050 fps in a stock G20 and 1,150 fps in my 6.5" 610 revolver with 800X. I know I have a bit more room to go and will keep working on it.