I've been on the hunt for some "nice" HK417 mag holsters for a while now. Eventually stumbled onto an old post that British Tactical made some of their MAGPi type holsters for them.
Tried some Tasmainian Tiger ones but theyre bungee and i cant stand silly string all over the place
A few...
Skadis trimmed to loose the rounded corners and bolted to stop any sagging and then to a spare 4'x5' plywood. Leans against a wall.
Making another soon
To counter this, i only have 1911/2011's... no problems as yet. I'm left handed so the mag release is on my outside so to speak. Wonder if your draw was pulling the gun in towards you and knocking the release on the way out?