So I’m new to the AR scene and I was watching “American Guardian” or “Best Defense” and they mentioned “only having 28 or 29 rounds in each magazine.” Are they referring to inserting a full mag and chambering a round thereby leaving you with 29 or is there some reason to not load a mag to full capacity, chamber a round, and then top off the mag? Thanks!
Downloading a 30 rd mag to 28 rounds will allow you to more reliably seat a fresh mag in the rifle with the bolt closed (like when doing a “tactical” reload).
Having your fresh mag fall out of the rifle on the next shot is no bueno.
That makes sense. Still be a good idea to train to tug after each mag insert though. Thanks!
It is also a non-issue with PMAG’s. The reason an aluminum mag will not seat properly on a closed bolt is because the magazine is loaded to max capacityand the round is actually hitting the bottom on the BCG. Magpul has apparently calculated that into their design.
Glad I bought PMag’s then! 
Only aluminum mags I have are the factory ones that came with it.
Even with 30 rounds and Magpul followers in Aluminum mags, I still have around a 1/4" inch depth left when I push down on a fully loaded mag. As always, use “push pull” when inserting a mag, and use what ever you feel comfortable with (28 or 30 rounds).
I own strictly GI mags, have a pretty good supply on hand, and have yet to purchase a Magpul Pmag. But, I have been considering purchasing a few Magpul followers to try out.
Regardless of make, test them. I’ve seen Pmags that didn’t work that way. 
It’s always good to have a healthy mix of usgi mags and pmags. I put magpul followers in the usgi mags so they can run better.
All my Pmags will take 31 rounds easily, and if I remember correctly, that’s a side-effect of being designed to function better with 30 rounds than a standard USGI aluminum mag.
That said, at class last week Costa recommended 28 rds in mags across the board, including Pmags. I did so, and it worked. I had a couple times that the mag was still hard to seat… Could have been other factors (or accidentally loaded to 30).
I bought crap load of DSG and BCM Aluminum mags with the Magpul followers. I even replaced the green followers on NHMTG USGI mags I acquired recently. They really do provide a smoother feed and eliminates “follower diving” malfunctions. I have about 50 Alum mags and around 100 Pmags now. I may get more if the prices at BCM remain the same on there “overstock” mags.
28 per mag, push/pull to check.
Yes Sir, I may just have to start doing the same.
I saw those “overstock” Pmags too. At that price I might pick up a couple.
P Mags are slightly longer to accommodate a full 30 rounds. Be careful however because you can sometimes load 31 into P Mags after they have been used just a bit.
Pat