Andrew Smith is a BJJ black belt based out of Richmond, Virginia. He is one of the owners of Revolution BJJ.
The Specialist's Bane
Specializing in a particular area of jiu jitsu (like I do with the Kimura) has tremendous benefits. For one thing, you have particular rabbit holes that can bring a person down, where you'll know what your options are, but your partner may not.
On the other hand, it can be incredibly frustrating as well, given that your training partners are likely to stop letting you do what you're good at. In practice, this makes deep knowledge (as opposed to wide knowledge) a double-edged sword. Fortunately for the obsessed, there are several different ways to reach the end point.
Here, we'll take a look at a person who doesn't want you to grab a Kimura grip, fearing your deep knowledge of the floating pass and the related system. We're going to get you the grip you covet anyway.
Beginning with a solid fundamental hip switch position (more on this below), your intention is to wait for your partner to try for an underhook, one of the most common reactions you'll encounter from half guard), and use this to catch the Kimura. However, your partner has cleverly wised up and hidden their arm behind your head. In the above video, Vince puts his right arm around my neck and hugs it tight, even turning his thumb toward him in order to avoid opening his elbow any. His defense is very tight. Typically, when catching the Kimura, you want to slide your far arm (left, in this case) through your partner's elbow, but because of the defense, use your right hand to fish through their elbow and on to the other side (the gap on this side will be considerably larger). Once you've created the space, you can slide your hand down to their wrist, ultimately straightening their arm and making it considerably easier to catch the Kimura.
The Key Detail
If you've managed to get to the point where your left hand is threaded through, but you're still unable to get their wrist down by their waist (maybe they're stronger than you, or maybe they're just stubborn and really tight with their grip), there's a way to make the technique work regardless. The surprising answer: facepalm! Slap yourself in the forehead, and use the weight of your head coming forward to augment your arm strength, forcing your partner's hand downward to their waist. From here, you can thread through from the other side with your left arm.
Hip Switch Is Everything
Remember, all of this is going to made much, much easier with a good hip switch from half guard, and there are some tweaks you can easily make for a much more savvy opponent. As your partner reaches for a very deep underhook (after all, they know you're going to try to catch a Kimura on them), change the very positioning of your body by pointing your knee toward their hips. Next up, drop your hips down several inches before driving your partner flat. Last but not least, switch your hips and snag the Kimura grip. Nearly everyone wants to switch their hips too early in this process, leading to being off balance and not really dominating the upper body in the manner you could.
I've been using the Kimura for over 20 years now, but this particular system has been in use for me for just over a decade. As such, there are lots and lots of areas where I've spent a great deal more time than my training partners, and those are the areas where I would like to play the game (assuming I want to "win" and not just explore other positions, which is what I do most of the time). Of course, nearly all of my long time students are defending my game extremely well, forcing me to either learn new positions, or improve the existing ones and create new variations. This is what you want in a gym, and you are capable of making this happen with thoughtful playfulness. As always, let me know if these techniques resonate for you! I love hearing from you.