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I think training the pistol with a slightly elevated heel at this point will be fine. Just don’t let the scaling of the exercise make you complacent. Keep that drive to improve your ankle mobility and earn your true pistol! I think the more you improve that range of motion, the more you’ll just start to use it in the heel-elevated version anyway, and you can slowly decrease the heel raise over time. This will also help you gain some strength in the pistol, at least from a hip and knee perspective, so you can use it as a means of loading a dorsiflexed ankle, which I think will ultimately help you drive your position gains along.