Hello, I read the owners manuals, and they are lacking some detailed information, so I can totally see where you would have questions. I did notice in another model's manual they confirmed you should not fire the shotgun without the choke tube in place. It said "Never fire or run cleaning tools through a barrel that uses choke tubes without a choke tube installed". I suggest you use the cylinder choke, which is not constricted, so safe for slugs, but also safe for the choke threads.

Good evening to you!! My Panzer arms lever 12 tactical came with three chokes: full, modified and cylinder. I know the manual said to not use a choke tube or the I/C. I personally use the Cylinder choke that came with it. If you really want to clarify the issue please call Panzer Arms customer service at 724-919-9633. I personally contacted them via there customer service contact form. It's more reliable and most likely to get a response from them in a timely manner. Hope this helps. Have a good rest of your day.
🇺🇸🇺🇸 'Merica' 🇺🇸🇺🇸
https://panzerarmsusa.com/contact/

Your gun comes with 3 chokes a full, modified and cylinder (F,M,C). Always use the cylinder choke for slugs. 💯‼️

Always use a choke (preferably Improved Cylinder or Cylinder) when shooting rifled slugs to protect your barrel's threads. Never shoot with empty threads; however, avoid tight chokes (Full/Modified) to prevent damage to the shotgun or, in some cases, the slug.

Hi Andrew and welcome to the community. Your Panzer Lever12 should have come with Three Mobil Choke Tubes, Improved Cylinder, Modified and Full. Check your complete box for the choke case. If not contact Panzer Arms at 724-919-9633 MONDAY – FRIDAY 8:00 am – 2:00 pm EST. Always follow the advice of the Manual that comes with your firearm as they maintain your warranty, and I would trust their knowledge of their own specific firearms rather than the general "internet", which won't service your firearm if their advice does not apply to your firearm. Cheers, stay safe and enjoy!. You can also contact Panzer Customer Service online at: https://panzerarmsusa.com/contact/