On 4/8/2016 1:31 PM, Bradley Smith via Callers wrote:
  Hello all! I'll be calling a session of
challenging contras at a dance
 weekend next month, and find myself lacking in the aforementioned
 challenging contras. I want to keep the session balanced, with a mix of
 dances that are mind-bending or heavily technical as well as some dances
 that are a step or so below that but that still have something
 interesting or unique. Would any of you be so kind as to share some of
 your favorite challenging dances? Thank you in advance! 
    Here is one I wrote that can be done as double or triple progression.
Stars and Stripes
Jonathan Sivier (1994, 1995)
duple improper, double progression; intermediate
1 - long lines forward and back
2 - left hand star 1 time
3 - right hand star 1/2, allemande left 3/4 with next
     neighbor to a wavy line across the set, men in the
     center
4 - balance the line, men allemande right 1/2
5-6 balance and swing partner on the side of the set
7 - circle left 3/4
8 - swing neighbor on the side of the set, end facing
     in
Stars and Stripes
Jonathan Sivier (1994, 1995)
duple improper, triple progression; advanced
1 - long lines forward and back
2 - left hand star 1 time
3 - right hand star 1/2, allemande left 3/4 with next
     neighbor to a wavy line across the set, men in the
     center
4 - balance the line, men allemande right 1/2
5-6 balance and swing partner on the side of the set
7 - circle left 3/4 and pass through along the set
8 - swing new neighbor, end facing in
Notes
3 - timing is tight, must move quickly, end in a wavy
     line with actives facing up, inactives facing
     down, men holding right hands in the center, 1st
     progression
5-6 balance and swing on man's original side
7 - 2nd progression for triple progression version
8 - 3rd progression (2nd progression for double
     progression version)
Jonathan
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Jonathan Sivier
Caller of Contra, Square, English and Early American Dances
jsivier AT illinois DOT edu
Dance Page: 
http://www.sivier.me/dance_leader.html
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Q: How many angels can dance on the head of a pin?
A: It depends on what dance you call!