Here's the follower that I printed yesterday at a cost of about $2.00. An injection molded part would be way cheaper but the tooling would cost some money depending on how many cavities, etc. The follower is very smooth inside the Lancer magazine tube and it works well, in fact it feels smoother than the Lancer follower. I've made a couple of small changes such as moving the boss with the hole for the spring .075" further forward, and I gave the spring a bit more clearance as it compresses by moving the two inside radii .100" further apart. I'm going to change the surface that the cartridge sits on, the .500" cylinder, from a straight cylinder to a tapered cylinder with .500" at the rear and .482" at the front to better support the cartridge. The rear "leg" could be shorter like the Lancer follower but leaving it longer provides more support for the spring as it compresses. This follower appears to be an improvement over running the BM follower in the Lancer magazine and it's a lot easier to print parts compared to filing. So at this stage I'm going to use the Lancer springs with ABS printed followers in five of the Lancer mags and call it good.
Underside of printed follower
Bushmaster follower on left, printed ABS follower on right, both in Lancer 20-round magazines
Underside of printed follower
Bushmaster follower on left, printed ABS follower on right, both in Lancer 20-round magazines