Area 419's opinion these are the only correctly made mag extensions on the market. Other magazine extensions on the market are simply rectangular blocks. If you look at your magazine the bottom is angled so when you attach a competitors extension, it is not parallel with the column of cartridges in the magazine. This probably works fine for +2 rounds, but it would not work for much if any more. They decided to do it right, and cut the attachment rail at an angle to the pocket in the mag. This means that the column of rounds travels straight down into the extension. This takes extra time on the mill and they chose to cut them in one operation on the 4th axis, but they feel that it was worth it to deliver to you the most advanced product of its kind. The fluting around the sides make an excellent gripping point for mag changes and also helps to remove some weight.
After starting with the American Rifle Company +4 mag extension, they realized that with a little bit of redesign that it could work equally well with AICS an Accurate mags. The 419 universal mag extensions are designed to work on a variety of magazines from the ARC 10rd mag to AICS 5 or 10rd and Accurate Mag in either standard bolt face or on SAUM/WSM mags. Easy install, great performance, and the quality you’ve come to expect from Area 419.
Expected Capacity Increase:
ARC 10-Rounders: +4 or +5 depending on cartridge
AICS & Accurate 5/10 Rd: +4 or +5 depending on cartridge
Accurate WSM 3 or 7 Rd: +3
Works with MDT metal AICS pattern mags, but MDT recommends to use one of their spring kits for proper feeding. They can be found here.
NOTE: **THESE DO NOT WORK WITH MAGPUL OR ANY OTHER POLYMER AI MAGS**