I'm thinking of building or buying a 9mm upper to mate with a standard AR15 lower on a non-permanent basis . I already have a good supply of both Beretta 92 and
Glock 17/ 19 mags. AND I'm in Kalifukya. Up in the pinned FAQ/ PCC info., its mentioned that Glock mags do not feed as well as Beretta mags.
I don't know if that is true or old wife's tale.

I had originally planned on using the Sylvan magwell adapter for Glock mags but now I am a bit hesitant with that choice. However, I can't
seem to find any adapters that take Beretta mags. Any help here would be appreciated.

https://getstern.com/mag-adb92/

my stern adapter wasn't inexpensive but it is well made and well designed, plus has a good LRBHO.



(i have no affiliation with this company)

I had a Sylvan. No built in feed ramp so its consistency is dependent on the barrel feed cone. My FM9 would choke on some hollow points using it.

Now I have the Stern with build in feed ramp. It feeds anything with no changes to the feed cone.

Gonna cost you 70-80 bucks more than lesser Glock conversion blocks but it will make a Glock fed AR9 with less than ideal geometry feed reliably and give you reliable LRBHO. I wish I’d bought it first.

So far, both replies are pointing me toward the Stern adapter. I hadn't realized the Sylvan lacked the LRBHO feature so that makes points with me too.

Now,I just need to decide whether to get the Stern adapter for Glock or Beretta mags....I have a bunch of both. Price difference is close enough.

Go Glock…

I was in the same boat, having a Brigadier and matching CX4. But if you ever decide to sell or repurpose the lower to 5.56mm… Glock stuff sells.

And Glock has sort of become one of the 9mm standards. Beretta has surplus, but that’s about it.