I found the best acrylic top coat at WalMart. Krylon Triple Thick Clear Glaze. I tried this with excellent results.
The downside is that it needs to be applied off the lathe. I put the barrels on a wood dowel to spray. Three coats, and they need to dry between coats. Then back to the lathe to level the finish, MM to 12000, and TSW.
The result is comparable to CA. Very smooth and glossy. I have only made a few pens this way.