These will work... with a little work - Magpul Industries PMAG 7.62 AC - AICS Short Action Magazine, 5 Rounds, 7.62X51mm NATO

I have an MDT ESS chassis on a Howa Action and while these fit the mag well, I did have to file them down a bit to get them to lock into place as well as filing down the retention piece to allow the bolt to slide smoothly. They were all very consistent and almost identical in the amount of filing I had to do to get them to function properly. Now they are tight but not too tight and they feed very well. If you get these for an MDT Chassis, be aware the the front side (Feed Side) will need to be filed down just a touch... maybe 1/32 of an inch. I was able to do this in about 10 minutes with a medium nail file.