Joong Gun
Joong Gun is an interesting departure from the rest of the colored belt patterns. Many have noted that it is more difficult than those it immediately precedes and follows. Interestingly enough, Joong Gun contains movements not found in the Pinan/Heian series, and instead borrows from older patterns. Joong Gun borrows most heavily from the kata Jitte, which Choi includes in his 1965 book (as "JIT-TE").
While many of the movements are out of sequence, there are too many positions from Jitte found in Joong Gun to be considered a coincidence. A sequence unique to Jitte features prominently in the next pattern, Toi Gye.
The following videos were used as reference:
ITF Legacy performance of Joong Gun.
Hirokazu Kanazawa performing Jitte, Bassai-Dai, Chinte (Shotokan).
"Shotokan Sensei" Paul Walker performing Jitte.
Unnamed student at Hideo Ochi seminar performing Chinte.
The ready position (B) for Joong Gun is similar to the opening salutation of Jitte. It more closely resembles that of Won Hyo (A), but more sequences from Jitte will follow.
For those curious, Choi's 1965 book does not indicate that either were ever the same.
The opening movement of Joong Gun somewhat resembles the opening movement of Jitte (center), but is even closer to Jitte's third movement (right). The sequences are unrelated.
Joong Gun continues North with a knife hand block into a vertical elbow. This sequence does not appear anywhere in the Pinan/Heian series. A similar sequence appears in Gankaku, Nijushiho, and Chinte. Later Chang Hon patterns draw from Gankaku, but I will use Chinte as the example here, as I believe it contains another sequence similar to Joong Gun. This sequence in Chinte is done to the rear, and therefore difficult to find clear video and/or images of.
After repeating this twice, Joong Gun continues with a high twin fist punch, then steps into a low twin fist punch.
This very closely resembles a sequence in Passai/Bassai-Dai, in which the body draws back while raising the hands together, then steps forward into a similar low punch. For visual consistency, Joong Gun is depicted from behind.
Next, Joong Gun turns and executes a high X block. This is another movement that appears in Jitte, though in a different stance and out of sequence.
Joong Gun's next sequence is a backfist, a circular wrist escape, and a punch.
This is a little tenuous, but it resembles a sequence seen in Chinte. I include it mostly because of the earlier elbow sequence that is found in both patterns.
The next sequence of Joong Gun is unique. One doesn't see this kind of shifting in place between stances in Karate kata, though it could possibly be inspired by the earlier knife-hand-into-elbow section of Chinte. However, it contains two palm pressing blocks, performed slowly. Slow palm pressing blocks are similarly found at the beginning of Jitte.
Joong Gun finishes with a 90 degree turn, angle punch, and two U shaped blocks, one to each side.
Jitte also features two U shaped blocks, although the sequence more closely resembles the one in Sam Il. Paul Walker's video (pictured here) also demonstrates how similar the chamber is between the two blocks.