If you have access to the small shrink wrap things, like the shrink wrap that's about 4 inches wide, wrap it moderately tight around it, just enough to keep the lams in line and then go for it. I used to have the same problem, but after doing that on my last bow, the lams come out perfect every time.
What I like most is if you just make it snug, the wrap has room to stretch, like it will when the glue comes out. Love it.