FWIW - VLDs are secant ogive bullets, your 175 SMKs are tangent ogive bullets. The major difference between a standard and VLD seating stem is that the pocket in the standard stem is roughly cone shaped near the mouth and the hole is not quite as deep. The VLD stem pocket only has a small flange near the mouth and the hole is deeper and wider, pretty much staying that way to the bottom. This allows the longer and sharper noses of VLD type bullets to be seated correctly without the meplat bottoming out, which can cause increased runout.
Can you elaborate on "wiggle"? The seating stem should really only contact the bullet ogive in a concentric ring somewhere below the meplat. Often, it will leave a small indented ring around the nose on a seated bullet. If you can detect wiggle when the tip of a bullet is placed into the stem, one of two things is likely happening. Either the stem and/or bullet nose is out of round and therefore are not contacting in a concentric circle all the way around. Alternatively, the meplat is bottoming out in the pocket, which also prevents the stem from contacting the bullet in a concentric circle and allows it to wobble as it is seated. In other words, the stem is seating the bullet by pushing on the very tip of the meplat itself, not a concentric circle just below the meplat. This seems the more likely, although a 175 SMK really shouldn't be bottoming out using a standard seater stem. You could check by removing the stem and pushing a 175 SMK bullet into the pocket. If the nose bottoms out before the bullet ogive contacts the outer edge of the hole, you should be able to tell. If that is really happening, a VLD stem may well solve your runout issues by providing enough room so that the nose doesn't bottom out and the stem can contact the bullet in a concentric circle and push it evenly (and straight) into the case.
