My take on a current project requires a 1/2" lonnng upcut spiral for mortising. I ordered a Whiteside RU5200 through Holbren (Brian is good people). The bit did not plunge very well and I was confused. I used a 3/8" bit to hog out most of the waste and used the 1/2" to get to finished size and depth.
Reflecting on past experiences with Whiteside CS I dropped them an email, explained my experience and asked their advice for an appropriate bit for my requirement. Here is their response:
If you will send this bit in to me I will modify it for you at no charge. This bit should plunge without any problems. We had a batch a while back that did not do to well and It may be one of those bits. I am in the process of changing all the spiral ends at this time to keep the end grind a bit more aggressive and user friendly.
I continue to be impressed with this company that takes a personal approach and an ownership in your satisfaction.