That's what I have, Chinese 5 rd mags. Although the bolt can get close to hitting the rear of the follower on some of them (manufacturing tolerances) it never catches.
I'll have to keep an eye out for those followers... I don't think is useful to everyone, it just fit my application:
In MI, we're only allowed single loads at the firing ranges - that would mean taking off the catcher after each shot (and I can do about 200-300 rounds a day, single load only). If I could somehow keep that charging handle locked after each shot (not covered by the catcher) I could theoretically go through a day's load and not have to remove the catcher unless it was to empty it.
Now if I were allowed to use a full 30rd mag, I wouldn't really care about the catcher thing since I'd have to empty it out anyhow. THis is why I didn't bother modifying my 30rd mags.
There's a true BHO, i think it's http://www.geocities.com/akcatch