i am very new to the 9mm blow back ar 15s
the day before the panic i picked up a CMMG 9mm lower for my dedicated 9mm build.
before i started on the project i bought 6 used 9mm c-products 32 round mags. there the old mags with the black followers, with the slick black finish. they appeared to be hardly used.
three of the mags worked good for a while and the other three would work well with around 20 or so rounds but the springs were very stiff, think like a bear trap stiff--
after firing a number of rounds the three "good" c-products mags started getting very stiff as well.
so i looked over at those mall-ninja places, they all said the older c-products mags were junk in 9mm, the newer ones were better but not as good as UZI or metalform/colt 9mm mags.
the other day JSE had a few ASC 9mm mags in stock so i ordered a few of um.
they have orange followers and the square springs.
the old mags have the long black follower and the very strong round spring.
i took some careful specs of the inside diam of the followers , length and so on. then i took two of the black followers and cut them down to the exact size and shape of the new orange followers from the new mags, then re-assembled the old mags.
on testing ONE of the old mags with the re-shaped follower worked perfectly. the other still got tight around the 20+ round mark.
i then gave the inside of the mag body a close look.--what i found was it had a few rough spots caused by the shiny black finish, so i took a 400 grit piece of sandpaper and polished down the rough spots on the inside of the mag.
and presto they now work as well as the new mags.
i then thought i wonder of all that follower re-work is really necessary? besides it is taking all day.
so i just sanded down the rough places inside the three remaining mags --leaving the old black followers as is.
and they worked just as well!
so if you got some problems with a 9mm ar mag a slight de-burr and through cleaning followed by a nice bit of lube will do wonders.
after the slight re-work their smooth feeding , the spring pressure is very nearly perfectly constant from 32 rounds down to one--
so far all the mags i have in 9mm work about the same, the cleaned up and well oiled old unreliable c-products seem to run very well indeed.
i figure the mall ninjas when their mags got dirty and sticky wanted to blame the mag and skip the PM-- we all know how real ninjas hate work--LOL!