Light Kit/dark Beer Attentuation Problems

[Pennywise]

Just wondering if anyone else that has used light kits like Lager or Cerveza to make darker beers has any problems with attentuation? I know DrSmurto used to do this when he was a kit man and thats basicly where I got the idea from. Only done it 3 or 4 times but every time I can't get it to drop below 1018, OG is generally just under 1050 with yeast being Wyeast 1056 (1.5L). Being a kegger now means I don't have to worry about bottle bombs so I just kegged one yesterday hoping that the racking would get it to drop a little more, but previous experiences tell me that prolly wont happen. I purged the headspace of the keg and will vent it every day untill it gets tapped, before carbonation takes place I'll draw a sample and see if it's fallen. The recipe was just a tin of Coopers Euro Lage, 500g carafa 3 spec and some EKG from 30 mins onwards at various points. Any thoughts as to why I can't get these to drop any lower?

 

[zabond]

Have the same probs myself, made quite a few kits with up to 500g spec grains & coopers goo most have finished 16-18 but tasted great maybe its to non ferm malts, last one canada blonde-caramber 100g-carared 75g-carapils 150g-med crystal 300g- ldme 200g- be2 1kg og 1054 fg 1016 ferm 15days@18* first time I made it but without be2 it finished 018 both saf04 21 ltrs
Russ

 

[Pennywise]

I use a fair bit of spec grain in most of the kits I do but I only seem to have this problem when turning a light kit into something dark. Even when doing full extract brews using LDME I use 500g or more of spec grains and seem to get down to 1012-14, and LDME is nutorious for finishing high when used as he only base. Possibly the darker malts are more dextinous?