I  have used Thermold mags as range mags for years in my 186 Mini with no problems. Unlike Tapco, no steel reinforcement, but these are obtainable. The plastic is modern Glass Reinforced Plastic (GRP), same as P-Mags, so reasonably stout.  Thermold Mini-14 mags have slots which will accept GI mag loader "Spoon".
https://www.budsgunshop.com/product_info.php/products_id/57875/thermold+30+round+black+mag+for+ruger+mini+14

Disclaimer: No financial interest.

That’s a good price.
Numrich Gun Parts still has Tapco Mini 14 mags for $22 as well. Pic & write up looks like the gen Is but I’ve seen several posts confirming they’re gen IIs with the metal reinforcements.
Not as cheap as the Thermolds but with factory 30s running $50 these are both bargains.
Never ran the Thermolds but I’ve read plenty of posts saying they’re good.

If Numrich still has Tapco 30-rd mags, I suggest buying them in lieu of the Thermolds, even though more expensive.  The Gen 2 Tapcos are reinforced by a steel band around the front, top of the mag, as you note.

I bought some of the Tapco mags from Numrich, and received Gen 2 Tapco mags.  So did another poster here, about the same time.  Scroll down: https://www.ar15.com/forums/armory/Ruger-Mini-14-mags/52-520559/

This might be a time where the ARF Mantra of "Get Both" applies...  

User call.  Absent a decent slip-over top-loader for Mini-14 mags, the Tapco mags must be loaded by hand, by individual rounds.  Thermolds will accept GI loader "spoon".  As against that, Tapco mags are reinforced by steel band around front of mag, reinforcing front of mag and the locating hole for receiver-mounted mag locating pin at front of mag well.  I've never seen any undue wear on my non-reinforced Thermolds at that point, but perhaps a lot more use in the future might display such.  So far, so good.

Owning both, having used both, and all things considered, I suggest the Tapco mags, while they are still available.  YMMV.  Both mags generally function properly right out of the box.

Any mag, once received, is worth taking apart, cleaning it internally, removing any plastic residue from the follower which could cause undue friction, and giving the mag spring a very light coat of CLP or similar.  Remove any manufacturing artifacts inside the mag body which might serve to cause the follower or spring to "hang-up" .  You want a follower with smooth, friction-free edges, and a mag body free of "manufacturing artifacts".  Seen many a mag body with crappy spot welds, and internal "artifacts" which caused follower to hang-up till the artifacts were carefully removed.

FWIW, I have re-habilitated a LOT of Mini-14 mags, bought during Ban years.   Many, but not all, were capable of working as designed, with a little "massage".  Some took more work than others. Someday, I might need to post a thread on how to (maybe) rehabilitate wonky magazines.  Folks at https://www.perfectunion.com/vb/ruger-mini-14-mini-30/ will assist for Mini-14/-30 mags.

While you all still have the opportunity, suggest avoiding all this hassle, and buy GTG mags while still available.  Some 10-rd mags are worth buying, just in case.  Suggest prices on such will be going up rapidly, and supply diminishing equally rapidly.  Suggest some 5-rd "hunting" mags as well.

Work-around for Tapco (and other mags which lack slots for GI "spoon") is Cogburn Arsenal Stripper clip loader:  https://cogburnarsenal.com/product-category/sights/

Works a lot like the similar stripper clip loader on M1A/M-14.  Not available for some models of Minis, and certainly not useable if a rail/scope/optics are installed directly atop the receiver.

This is one of the many reasons why I (and others) have installed Ultimak scout rail on our Minis.  YMMV.

Disclaimer: No financial interest.

For the record, I did "get both"...  Ordered Sunday, Numrich shipped yesterday, Bud's has not shipped yet.  That is not a complaint, I don't know what their situation is with a pandemic and crazy weather and god knows what else.    I'm in no hurry, it's too damn cold in Iowa to shoot anyway.  

@raf

I’d be really interested to hear about that. I have a few random mini mags that I need to “fix”.  I have a suspicion the idea of fixing mags may become a whole lot more appealing before long.

Go to perfectunion, Mini-14/Mini-30 forum.  Many approaches there, including mine.

Tapco's arrived a while back.  I'm no expert, but they do seem to be the Gen2 with the metal at the top front.

Thermold's arrived today.  They seem a little less solid than the Tapco's, and they are surprisingly short.  Maybe it's just that the Tapco's have a more pronounced baseplate.  

Anyway, I guess we'll see what happens when I get them to the range.



Did PerfectUnion ever get some damn moderators?  I gave up on it years ago, just too much awfulness...

Opinions vary.  You'll have to see for yourself.  Search function there works pretty well, so suggest you use it and do some reading to see if your questions have already been addressed.