Friction during sound removal

I recently moved up to a sound that is 8 mm in diameter. It's hollow and smooth stainless steel. I've only been using KY Jelly so far for lube and it has worked well previously. I had no pain during insertion and removal, nor in between, however, when I tried to remove the sound it didn't slide out easily. Instead, it was like I was tugging my penis from the inside. When I felt such resistance, I was concerned about using more force to remove it. I ended up removing it with no pain, blood or discomfort other than the moments of mental concern. I'm wondering if there is a better lube to use or if this is a known issue with hollow sounds. I noticed that lube had worked its way up all the way to the opening at the head of the sound which I'm sure created a vacuum. I'd like to prevent that since I figure that one of the natural advantages of a hollow sound, aside from the cum-through and pee-through capabilities should be the prevention of creating a vacuum in the urethra.

You won't create a vacuum in the urethra, urine will fill any space left by a sound. You may have bleeding on removal if you have to tug it a bit, especially if that happens often.