Unfortunately, the M is not a full size pistol (hence the M for medium) and most thigh rigs or drop leg holsters are designed for full size pistols. That said, if you want a molded thigh or drop leg holster you'll have to have one specially made for an M-series...because they just aren't out there.
Luckily though you can find some tactical nylon thigh or drop leg holsters that will work and retain the firearm well enough. I would recommend a "TACTICAL HOLSTER" from Tactical Tailor (http://www.tacticaltailor.com). The one designed for the Sig 228 works well because the Sig is only .05" longer than the Steyr M and only 1/2" more in height. Its adjustable so it doesn't ride up on your boys and holds its form really well when you remove the pistol from it making it easy to reholster double quick.
But don't take my advice alone...check out some websites find what right for you...maybe lay out the coin for something custom made.
Safe Shooting
Luckily though you can find some tactical nylon thigh or drop leg holsters that will work and retain the firearm well enough. I would recommend a "TACTICAL HOLSTER" from Tactical Tailor (http://www.tacticaltailor.com). The one designed for the Sig 228 works well because the Sig is only .05" longer than the Steyr M and only 1/2" more in height. Its adjustable so it doesn't ride up on your boys and holds its form really well when you remove the pistol from it making it easy to reholster double quick.
But don't take my advice alone...check out some websites find what right for you...maybe lay out the coin for something custom made.
Safe Shooting