There is one range I use occasionally that does not allow holsters. I practice from ready position on that range. Another range I have been to in my area (exactly twice in 4 years) not only does not allow holsters but has a “no more than one shot per second” rule that is strictly enforced and the ROs will get after you for “aggressive” shooting stances or techniques. Only thing you can work on there is basic marksmanship.
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Todd, thanks for the tip on practicing SOTM indoors. That will work at one indoor range I use. My primary indoor range gives you too small of a box to try that, but* as long as you stay in the box and are safe they don’t care about anything else. I have learned to keep my workspace compact there (at least that is the excuse I use). It is my primary practice range simply because it is only 10 minutes from my work and it only costs $6.00 to shoot there. Time and money are two big factors for my live fire schedule.