Ahhh….so there is. Interesting.

Earl

__________________
Earl L. Cagle, Jr.
NAR# 29523
TRA# 962
SAM# 73
Owner/Producer
Point 39 Productions

Rocket-Brained Since 1970

I guess then it depends on who's BT-56 you're talking about.

Looking at the 2007 Estes catalog, BT 56 specs to:

O.D. 1.346
I. D. 1.304

That's pretty close to ST-13, which is what we thought was true.

__________________
-Wolfram v. Kiparski
NAR 28643 - TRA 15520
MTMA Section #606 President