mikey:

Are you cutting a big slip and folding it?

You can try using the leading edge of the feather but I bet you'll find that the biots give you trouble. Some of the secondary feathers from in toward the body may have long enough biots...so it's worth a poke.

For the sake of the Tying god's I'll add two comments:

1. You can (and "should" ) use matched left and right wings and take matched slips from each wing (see thread on Quill wings, the same rules apply). Forgive me if I interpreted your question wrongly.

2. The late Poul Jorgensen advises using the tail coverts to tie muddles. They are softer and very attractive, albeit a tad different than what the Muddler had morphed into these days.

I think a very sparse muddler tied with black or very dark brown hair and fished just under the surface in muddy shallow riffles is a deadly sculpin imitation.