If there's one main takeaway from these stories, it's that Lockman's conception of what exactly Gyro should be doing as an "inventor" is distinctly different from Barks'. For better or worse? Well, I suppose that's a matter of opinion, but I will speak more of it shortly.
"Brain-Strain"--again with the painfully generic titles. You see an opening splash panel like this in a Barks story, you expect the narration box to read "how did Donald and Gyro find themselves in this predicament? To answer that question, we must turn to the previous day, in Duckburg." Just shoving us into the action like this with no explanation is kind of awkward. And are we really meant to believe that Donald is this dumb? Sure, he does dumb things often enough, but generally this is either the result of hubris or of coming up with ideas that seem like they could work. Just straight-up building a boat with thumbtacks? I have my doubts. No, it's not a major part of the story or anything, but I feel like you should try to get the small details right anyway. Certainly, there's no compelling reason why the boat's disintegration had to be predicated on something so dopey.
If we remember back to that one Barks short where Gyro has a new pool but is self-conscious to use it because he doesn't want them to know he can't swim…well, he can't swim at all, strongly or otherwise. I guess we can say that this takes place after that, however. Sure, why not? Actually, this whole "OMG how do I get to the island?" bit is neither here nor there; it's just Lockman making time with something that doesn't have any connection to the central plot, such as it is.
Yes! Sulphur, charcoal, and saltpeter make gunpowder! I learned this fact in elementary school. We had this cool little quasi-educational role-playing game going on where we controlled different tribes of people in different parts of the world, and one of the rules was that our people could invent a thing if we could describe how it's made. Our tribe was obsessed with inventing gunpowder, for some reason--which we did, though as I recall it never served any very good use.
So this is a science-class type of invention--something that someone, in real life, could actually copy. That is not remotely the sort of thing that Barks would have Gyro invent; for him, the inventions were more or less the same as magic. And if we look at the other stories in this issue, we can see that, while they aren't like this, they're also distinctly non-Barksian. "Mighty but Miserable" probably comes closest, but all of them approach the concept of "inventing" from different angles.
What do I think? Well, to me, the problem with Lockman's work is not that he has a different way of characterizing Gyro than Barks does, but rather that he doesn't have a coherent way of characterizing him. I find that the character becomes kind of fuzzy and indistinct when he's going around doing all these miscellaneous things: coming up with sports and being a city planner and, here, playing Bill Nye, Science Guy. These stories aren't exactly bad, but I think I'd find them more compelling if Lockman had a distinct vision. Like it or not, his stories are more action- than character-based. Barks was great in part because he did both action and character extremely well. Lockman, not so much.
I'll end on a positive note, however, and say that, if we have to accept that Donald is this inept, him going from using thumbtacks to railroad spikes is kind of funny. And that's about the level of praise I would use for this issue: not great, but semi-frequently kind of funny. Hey, that's not so bad. It could be, and often was, a whole lot worse.