Slightly different but I recently got the Arthurian Veteran M16 which is a rebrand of the E&C one and since E&C is a OEM for some of the Specna stuff I was expecting their metal mid-caps (https://www.airsoftzone.com/en-gb/p/magazin-m4-midcap-120rds-10932510000/) to fit perfectly as I was under the impression that E&C would make those mags as well. What a surprise it was when I put one in and it just wobbles around 360 degrees, at least it doesn't drop out easily when trying to pull. I then tried their s-mag which sits nicely and firm. I ended up getting actual E&C mags which only slightly wobble to the sides but seem only when doing so with hands and not whilst waving the RIF around.