Adjustable squeezer ram doesn't fit?

I bought an adjustable ram from ATS (the 214CAR) and it doesn't fit. It also doesn't look like the picture on their site; this one looks more like the AE274 listed except it has a different anti-rotation design.

The base of the ram is 0.630" wide but the opening in my riveter is 0.615" wide near the yoke holders and tapers down to about 0.525" wide. I can probably grind off the extra 0.020" or so in width and then round over the corners to make it fit but is this typical?

My squeezer is a genuine CP-214 but it's of unknown vintage.

Similar issue

I got my adjustable set holder from Aircraft Spruce, and I had a similar issue where it would bind up because it was just a little bit too big. I filed mine down about 0.020? total on the sides to get it to slide freely. A few minutes on the Scotchbrite wheel did the trick, and having a pneumatic squeezer has saved me all kinds of time and trouble.

I had the same problem with mine and employed the same solutions mentioned above.

I ended up grinding the base down to 9/16" and leaving the little triangular anti-rotation tab. Seems to work; it goes up and down freely. I haven't set any rivets or dimples with it yet though.