Does not fit mdt field stock - Amend2 AICS Short Action 5-Round Rifle Magazine

Don’t know if my rating reflects the product exactly. But picked one up to try with my Field Stock. I already had one MDT polymer mag and had hope this one would work and I could take advantage of the price. But won’t lock into the rifle and so won’t feed either. When side by side the lips look shorter than those on the MDT magazine.