I go a little further than that, I require the gun available to me at my home reloading shop so I can correctly check it and the ammo I will be preparing for it, as often as needed, BEFORE going to the range for actual firing tests.
Every gun and ammo combination is slightly different, within its specs and tolerances, and every gun is not always within those specs and tolerances, and some that are still don't run "right" unless the ammo is loaded a certain way, and not every loading that is within industry specs is going to fit and work in every gun. It should, but we're not in a perfect world and the time to find out a particular gun needs ammo loaded a particular way is before you set up to shoot on the range.
AND, especially before you load a quantity of ammo!
there was a fellow here a few years back, had ordered a pistol in a rather uncommon caliber, and had gotten a bunch of components, and was going to load ammo before he got the gun.
I, and some others advised him not to do that. He was eager, and loaded them up, and after he got the gun found out that what he loaded didn't fit, and had to tear down and redo about 500rnds.
IF he had waited until he had the gun in hand, so he could test fit sized brass, and his first few rounds of loaded ammo, in the gun (not a gauge, or measuring against book spec numbers) before going into volume production, he would have saved himself a lot of work.
Also, there is always the question of any ammo you load for someone else not being suitable for THEM, in their gun.
One fellow I knew got a .44 Mag SA, and to fit his small hands, got it fitted with a birdshead grip and a Bisley hammer. He asked me for some ammo. I gave him a box of my (heavy end) midrange loads (they fit fine) a 240gr LSWC over 10gr Unique. (approx 1100fps +/-). This is not a full magnum load, but for him, in his gun with its birdshead grip, it was too much. It hurt him to shoot it. (in that gun, it would probably hurt me!). In my S&W and Rugers it's not unpleasant.
Not everything that is within the specs is suitable for every gun and shooter.
Dangerous /unsafe is a fail. Doesnt' fit is a fail. Safe, and fits but not suitable, is also a fail.
Lots of times, what people ask for, because they read something saying "this is good" turns out to be unsuitable for them. And, if you loaded it, (even at their specific request) they generally will blame you for it not being "right".
If they are willing, (and provide their own components
) I'll let them learn how to load for their gun, using my tools, under my instruction. If they won't do that, they can always buy factory ammo... (maybe, if they can find any these days
) at what ever the going rate is...