Anyone had a similar issue and found a hack?
I have bought the tools on occasion, but for the most part drill and tap my own so that the tooling case is fire-formed and fits snug compared to a standard tool and gives less slop in the measurement.
When I start to modify the case, I run the mandrel diameter up in steps till the bullet will just slide. I am going to assume you don't have the mandrels or you would have already done so.
If you cannot borrow mandrels or don't want to invest in them, I would check the neck for dents and iron those out first. If the size is to blame and you don't mandrel, I would apply grit paste to a brass rod or sacrifice a bullet and spin inside that neck till it slides.
If you don't have the tight brass rod or a way to hold the bullet, a split cut into a dowel rod can hold sand paper or ScotchBrite media and be spun to help smooth and open the neck as a last resort. As a last resort, a tight fitting bronze bore brush with grit paste will also work. Start with rotation speed and then slow the rotations and make more plunges before you finish, and clean up well.
If you stay in this game long enough and you trust yourself with tapping threads, it isn't difficult to make the case modification and you will eventually want to learn to mandrel necks, so make sure you add the over-sized ones to your toolbox and you will be able to make your own tool. I realize everyone isn't a machinist, but maybe your friends are and if you own the drill and tap they can do this for you. YMMV