Resurrecting this from a different thread:
I held off on using my piercing for real chastity security until I could stretch it up to 5mm (4ga).
Back in the day, MaleChastityNow didn’t have the Prince Albert pin that could secure me inside the Contender at anything smaller than 5mm (4ga) back in 2014. Though I feel like I probably could have managed with a 4mm (6ga) gauge.
Somewhere here, and on ChastityForum or LockedMen among others, there’s an old post of mine where I collated the various advice and insights from all the writing available to me in 2014. That included guidance from Thumper (MN) and others.
I believe 5mm (4ga) is widely regarded as the sweet spot, and jewelry looks great at that size too. Just make sure you don’t go smaller than 3mm (8ga), or you risk a cheese-cutter wire effect leading to migration. I remember feeling somewhat cautious yet comfortable in a 4mm (6ga).
Perhaps someone could dig into the medical and anatomical literature to define exactly how much pressure (force per area) our skin can withstand before starting to adapt by pushing out what might be seen as a splinter or thorn (just my guess, really). The wider the surface area, the more of that force is distributed. Consequently, the skin between the piercing and the urethral opening should remain stable.
5mm (4ga) also has enough lightness when using stainless steel rings so gravity doesn’t pull too hard on it.
When you move up to 6mm (2ga) and larger, I’ve noticed some steel jewelry can feel heavy if not supported by clothing or a chastity device. However, that’s Not dangerous though.
For heavier gauges from 8 mm up to 10 mm (0 and 00 gauge), you really do need support even for standard PA jewelry; opting for titanium instead of steel is wise because the weight can become problematic otherwise. I used BodyCircle’s 68 gram weighted ball as a maximum safe stretching limit, which also serves as a reference point for chastity device weights.
That said, I experimented all the way up to 10 mm and found it really feels filling and huge there. But then I stepped back down to 6mm (2ga or 1/4”) and am very happy with that size now. I don’t want to go smaller just because the jewelry I’ve bought in those sizes costs quite a bit more than what you get for 4ga.
I enjoy wearing 2ga when my wife unlocks me so she can “be good” without needing extra help from devices. It jingles and teases, tempting me away from my no-touching rule.:)
Lastly, I know that with my 6mm PA pin featuring a blunt end fastened inside both my Contender and Glans Armor cages, urine flows smoothly around the shaft and reunites at the tip. This creates a smooth laminar flow; I don’t splash or spray if aiming off-center.
Because of this setup, I can use a urinal cleanly without any potential embarrassment. I’m not entirely sure how well 5mm / 4ga worked for urine flow though. If anyone out there has a 5mm/4ga Glans Armor, or other open-front devices with a PA hook at the 5mm mark, I’d love to hear about their urination experience and comfort level when using that size to secure them in a shaft-only device.