Yes, you CAN load a full 30 round mag on a closed bolt

[ECU Pirates]

I've searched for ages. I love my 7.62x39 AR's and desperately want polymer mags for them.

Sounds like a business opportunity. Let's make them!

 

[Airborneguy]

Sounds like a business opportunity. Let's make them!

We should. It's pretty easy to get the parts and assemble them. I just want a basic polymer body with 7.62 followers.

 

[meketrefe]

We should. It's pretty easy to get the parts and assemble them. I just want a basic polymer body with 7.62 followers.

The biggest issue is that because of the prononced taper on the 7.62x39 the rounds do not stack well straight so they start curving pretty aggresively.
I guess for 10 rounds you could use a 6.5 grendel magazines and follower but the problem is they are also made of steel and aluminum.
If one found one in polymer all one will have to do is to file a little the front rib to make sure the bullet portion will stack well but again no luck with
the other variants neither.
I think the stainless steel ones coated in black are pretty good magazines and more durable than polymer. that is probably why they do not make them and
obviously there is no much market for them.

 

[Clipazine]

If you have a magazine that will only function reliably on 29 rnds, you do not have a 30 rnd mag,you have a 29 rnd mag that you can stuff one too many in.

It's not a function issue for me, just an ease of loading.

If it's an AK mag, i'll load it to maximum. The hinged lock-up makes it effortless to overcome the spring tension.

 

[Shadow2]

30 round magazine, Why would try to shove 30 mini balls into a barrel at once?