The Witness Elite Limited 40 S&W offers the potential for having magazines that can hold of 21 + 1 rounds, legal for USPSA competitions! Don't be mistaken, the mags do not come this way from factory so you need to modify the mags yourself or get them at my shop. There are a few simple rules you should follow to have reliable hi-cap mags:

Modify your factory mag to fit 21 rounds (USPSA rules)

1. Order the Grams Follower & Spring Kit with the Henning H-140 magazine pad for each mag from my shop.
2. Disassemble your factory mag; remove the floor plate, spring and follower.
3. Before inserting the Grams FSK, make sure the follower is leaning to the right. The reason for this is that it can pop through the mag lips. We don't want that. So use a needle nose plier and bend the spring just under the follower until it is tilting (quite a bit) to the right. (Take the follower off and bend the last coil of the spring.
4. When you assemble the mag with Grams and the H-140 pad you'll quickly see if the follower stays inside or pops through. If it does, take it out and bend the spring until it stays inside.
5. Assemble and test.

If you don't want to go through the trouble of modifying the mags, just get the competition ready mag here. Note: The pad still needs to be slightly shortened to be legal!

Modify your factory mag to fit 18 rounds (IPSC rules)

1. Order the Grams Follower & Spring Kit with a Factory Aluminum magazine Pad for each mag from my shop.
2. Disassemble your factory mag; remove the floor plate, spring and follower.
3. Cut 2 coils off the Grams Springs. Bend the spring to make sure the follower is leaning to the right as you would for the 21 round mag.
4. Assemble the magazine and test.

Slide Stop will not lock the slide back anymore

Since this is an aftermarket follower, it doesn't work with the factory slidestop. Personally, I don't allow the gun to lock back at any time anyway, so I recommend getting the EGW Slide Pin. It eliminates any mismatch issues with the factory slide stop.

Pay attention to the brass quality

For major matches I always use new cases. Since the Tanfoglio mags are straight wall without any rails to reduce the cartridges' riding surface, I recommend new nickel cases as it's more slippery than brass. When you're reloading used brass, make sure you use the EGW Undersized 40 S&W die.

Let the mag spring take a set

When you've first assembled or ordered your new magazine, it'll be tough to get 21 rounds in it. Don't expect 21 + 1 right away. Shoot it for awhile with 20 + 1 and let the spring take a set. It will open up and before you know it you'll have 21 + 1 mag capacity.

Mag spring life

Expect to get 200 cycles times 20 rounds of each mag. That makes 4,000 rounds fire out of each of your extended mag setup. If you have 5 mags total, expect to replace your mag springs after 20,000 rounds. That way you'll always have reliable magazines.