I'm going to build an AR-9 My question is about the two options. I can use a standard AR lower and build using the insert and standard colt mags or I can buy the specialized AR lower that uses glock mags. I would prefer the standard lower but other than magazine capacity does anyone have pros or cons?

Glock style aftermarket mags are cheap and easy to find and seem to have good reviews on reliability. I would want a bunch of extra mags for it and when you calculate the cost of mags some things get expensive quick. A buddy got a ghm9 and thought he had it made, then went to buy mags...they were about 100 bucks a pop and i think he only found 2-3 in stock anywhere.

https://www.youtube.com/watch?v=JyNhPUP1ZZo&t=482s

I watched this video earlier and thought it would be a decent option if someone was looking for a pcc. Costs about as much or maybe less than trying to even build a palmetto state ar9. Im still waiting on PSA to come out with their mp5 clone. Depending on the price it would be between the PSA or PTR mp5 clones.

Checked on the mags. They are about the same price but glock does have more options like higher capacity and even a drum. Thanks for the reply.

Look at Tennessee Arms the sell an ar9 lower built for the glock mags

I swear at one point when i was researching them i found a drop in adapter that was well built to change a standard lower to accept glock mags. If i remember right the adapter would have cost about as much as a purpose built complete lower.

Nope, can't happen with a standard lower. Glock mags are wider.

I have a Stern Defense (Glock) and love it. Probably got around 2000 rounds through it and it runs flawlessly. I was just going to buy the mag adapter only and build the upper. I ended up buying a kit with the mag adapter and complete upper from Stern Defense. They are made in Missouri. Good people to deal with.

I tried the mean industries endo mag inserts and gave up on getting them to work. I think they would work, but I didn't have the patients to deal with them. I ended up ordering a Completed lower from PSA that takes the Glock mags. I love it. I still have 2 of the inserts new in the pkg I would sell cheaper than I pd if anyone wants to take a wack at getting them to run.Endo mag link

Feedback I need to hear either way... thanks stumper.

I forgot to mention the Stern Defense upper has last round hold open. When used with their mag block.

I use the colts. They are pricey unless you buy the colt-style knockoffs, which work fine.

Humph! Learn something new every day!