You can also use para P14 mags, but the slide won't lock open on the last round.
Mecgar P14 mags are the same otherwise.
I had David Tillander make some followers for me. He often makes pistol grips and such. He sells on ebay, gunbroker and has his own website too.
I had to send him one of the k245 followers because it has the ledge to lock the slide back, but he copied them and returned it along with the ones that I ordered. They weren't much. I don't recall how much they were, but seemed like only maybe $2 each or something like that? Seems like I paid $10 for 5 of them. I even had him do it in bright orange for hi-vis.
But that's been years ago. Unsure what it would cost now or even if he is doing custom work.
He also made a copy of my old stevens single shot breakdown trigger guard. It was impossible finding a replacement at the time, and he was able to make me one to fix an old gun with too.
Or, just buy the more expensive sars mags. But as I said, the P14 mecgar mags work fine. Just they don't have the ledge on the side of the follower to lock the slide back when empty. Otherwise, they're one in the same.