So one of your brands of ammo is keyholing, so the answer is to get into reloading?! That’s a bit of an over reaction but if that’s what it takes to get you into the reloading game, then so be it lol.
But seriously though, back to your OP, you’re getting into reloading to really just answer a question for yourself about the bullet size. So all you really need is 5 or 10 rounds, right? That’s lot of money invested if it turns out the bullets aren’t the issue.
You can make a small batch very easily. All you’re going to need extra is a bullet puller, and you can grab one from your local gun store for about 30 bucks (hammer type). They work fine, but are slow. Watch some YouTube videos to see how hard you really have to swing them. (Harder than you’ll think they’re capable of). Stuff a piece of foam in the bullet end to help protect the the nose of the bullet if you’d like.
Collect the powder and carefully put it back into the case. If you don’t have a small enough funnel, just make a little paper one.
If you have some bigger bullets on hand, great. If not, you could just sacrifice a few other loaded rounds with the right size, and pull them too, just make sure the weights are identical. (Same grain)
Then you can seat the new bullets into the charged cases by using a couple of blocks of wood in your bench vise. Drill a 5/16 hole in one where the bullet can be cushioned and kept straight. Just slowly close the vise and gently push the bullet in. No need to resize or crimp as the case hasn’t been blown out like it gets when firing, and you’re stretching it by seating a larger bullet. Use your caliper to ensure it’s the exact same length as the original rounds were.
Then go to the range and see.
... but don’t let me get in the way of a perfectly good excuse to get into reloading lol ;-P Have at ‘er!