All though AICS magazines have become the "standard/go-to" pattern for the industry when it comes to bottom metal and chassis DBM's there actually is no such thing as a AICS spec. We have measured hundreds of "AICS" magazines from different manufactures and can assure you there is no consistency. Comparing a AI brand, Accurate, MDT, and Magpul they will have different measurements. Even measuring 20 magazines from the same manufacture made over 5 different years will have different measurements. Over the last 10 years of manufacturing chassis we have continued to update the magwel design to try and cater to the lack of tolerances. Unfortunately it is rather impossible to make every single magazine fit perfect without sacrificing fit/performance. Make it too open to accept all - magazines will be loose and sloppy. Make it too tight, limiting rattle and increasing feeding on a specific magazine - prevent all the others from even fitting. We have talked with AI, Accurate Magazine, and MDT on if it were possible to all get on the same page and actually have specific tolerances to hold and to be honest other than MDT the response was not helpful. Shout to MDT for agreeing that it would be absolutely AMAZING if everyone could cut magwells and manufacture magazines to a specific specification range.
Now in regards to steel AICS magazines it is somewhat understandable that it is difficult to hold consistent tolerances as they are just bent metal. Polymer is a little different. Compared to a chassis that is machined on a CNC that can be held at tight tolerances. So from the above statements it is interesting that one is willing to modify a $600-$1,500 chassis because of $50-$90 magazines.
Give us a call and we can trouble shoot this issue with you as you are not alone on this.. Magazines can be (not always) the most frustrating part of the rifle build. But I can tell you that more often than not trying a different magazine is a easy solution. We sell the Accurate .223 magazines that you can try, or relieving some of the plastic on the magazine might be necessary. Might want to also look and see if the ribs on the MDT magazine are going into the magwel ... I do not know about the current design but the older polymer MDT magazines that had the rib design used to not work with many other platforms because they would go into the magwel on some application causing resistance. If this is the case (not saying it is) then some filling on those could be all you need to do. Again we would love to discuss what you are experiencing and try to make sure your rifle is working 100%.
