So, I've had a relatively similar thread, but this is a little more specific so I'll make a new one.

Basically I started shooting steel challenge with a full size centerfire pistol with iron sights (namely a Sig P226).

Turns out going from a single stack 45 to a double stack 9mm actually makes me somewhat competitive (went from the dead bottom of the pack to approaching the middle after a couple matches), but now that I'm beating people I feel bad because in a way I'm kind of cheating.

Essentially you are supposed to start with a pistol in a holster, then draw and fire at five targets. For ABs the holster is supposed to be a vertical holster attached to your belt at the 3:00 position (ie your right hip). For me that's not even feasible because of how narrow my chair is (I guess at this point I should say I'm a T8ish complete in a 13" wide TiLite ZR), and even if my chair was wider it wouldn't be safe because I have so much leg hanging out in front of my draw.

The matches are relatively flexible, as they obviously don't want to exclude me, but they also aren't super familiar with people shooting from chairs, so if I tell them I'm going to do X, they will probably go with it, which is a good and a bad thing, because it leaves me some room to be creative, but also (at least in my mind), puts the full onus of safety squarely on my shoulders.

Right now I shoot with my chair roughly at a 45 degree angle to the targets, with my casters pointed more or less at the rightmost target, because I am a right handed shooter it would be extremely awkward for me to shoot (at least with a proper two handed grip) at targets that are to the right side of where my chair is facing. Also I tend to clear targets in a left to right manner, but this is not necessarily a requirement.

So I was thinking about mounting a holster on the outside of my left downtube, essentially just to the left of my left knee, and probably at a slight angle, like maybe 22.5 degrees (half of 45) left of forward, with the barrel pointed straight down and the grip of the gun about three inches higher than my knee so there's no obstruction when reaching for it.

I don't have a holster picked out yet, but mounting a holster feels like something of a daunting task. Right now with my ZR there are limited options (soon I will have a new TR which might offer more mounting points) for where to actually attach the holster. I'm sure there are some sort of bicycle frame mounts I could employ, but I foresee an expensive process of buying multiple holsters and mounts and straps and duct tape and velcro and superglue and still not getting a stable product.

Basically these are the requirements I am trying to meet:
1. Mounted to the outside of the frame just to the left of my left knee with barrel pointed at the ground and grip several inches above my knee level.
2. No drilling into my frame... I don't know if you guys do that, but I'm definitely not up for it, not with my ZR (for which I currently do not have my backup chair), and for sure not with my TR which will be brand spanking knew and for which I fought and shed blood, sweat, tears and several dozen green pieces of paper with Benjamin Franklins face on them.
3. Relatively quick mounting. I don't want to spend more than 10 or 15 minutes adjusting, strapping, tightening, tensioning or fiddling with the holster to get it mounted each time.
4. Secure - the range I shoot at most of the time has some relatively serious hills (maybe a 1:6 grade) that are made up of loose gravel that I will have to traverse with the gun holstered, often in a wheelie to avoid my front wheels digging in, and the holster will need to stay securely mounted throughout.

I figure this is grossly similar to attaching a cup holder to a wheelchair (something I've never had the desire to do), so if you guys have securely attached a cup holder to your frame, lemme know how you did it and how secure you think it would be.

The gun itself (not counting weight of the holster, which will probably be a plastic/kydex holster) weighs about 42 ounces when loaded.

Any input you all have (other than telling me how i shouldn't own or shoot a gun... I'm well aware of my wicked ways and have no intent to change them) would be greatly appreciated.