Your buddy does not know what he is talking about regarding checking firearms.
Per TSA regulations you have to have Non-TSA locks on a case containing firearms. Additionally, only you are to ever be in possession of the keys. Nobody other than yourself should ever have access to the actual firearm. They aren't even allowed to touch it.
Depending on the type of case, you may choose to put some tape over the latches to keep them secure after the inspection. On a couple of my less expensive rifle cases, I do this ahead of time. I double over the tape at the end to create a pull tab to easily peel it back. One strip of tape for each latch. I actually find that black hockey tape works better than duct tape and is less visible.
For regular checked bags(non-firearm), I never put locks on because TSA WILL break them off or destroy your bag if they want inside of it. In either case, the bag will be out of your possession at that point and there will be nothing you can do about it.
Having traveled extensively with firearms here is what I normally do.
Hard sided case that will accept padlocks. I don't trust the locks that normally come on cases.
For my single actions, I remove the cylinder and place it in the case beside the gun.
For semi autos, I lock the slide back and place the unloaded mag in the case next to the gun
Bolt rifles have the bolt removed and secured inside the case.
Nothing is required other than ensuring they are unloaded, but I do it as a precaution.
On check in, tell the ticket agent that you are checking a firearm. No need to make a big deal about it. They will have you verify it is unloaded and have you open the case to insert the bright orange "Firearm Unloaded" tag. If it is a pistol case I normally place it on the scale and open it in the direction of the ticket agent. This minimizes the view to the rest of the sheeple in the ticket line and minimizes the issue of anyone freaking out. Once the tag is inserted, the case is closed and locked up by you.
Depending on the airport there are several procedures I have seen.
1) The ticket agent will take your locked case and hand walk it to the TSA X-Ray machine. TSA X-Rays it and if everything checks out, you are on your way. (Philadelphia, PA)
2) You will be escorted by an agent to a separate screening area where TSA will check in your firearms case then proceed to tear apart every checked back you have, go through every single pocket, unload a bunch of your stuff on to the counter and swipe the inside of the bag with their bomb sniffing machine paper. They will then jam all of your stuff back into the bag in an unorganized fashion and force the bag shut (zippers straining). This has happened to me in this airport every single time I fly through there. (Orlando, FL)
3) You hand carry your bags to the TSA X-ray screening station, drop them off and wait for TSA to check them and ensure they are good to go (Dallas, TX)
