What Coughlin is saying about the packer is dead on. If the hole in the 'packer' (like a pen barrel) is larger then the hook diameter you will not pack as much as bend the hair over and push it back. What Coughlin is describing is like this from Brassie
http://hareline.com/images/harelinejpegweb/BHP.jpg
Or this from Anvil
https://www.docsflybox.com/sunshop/i...l_1760_APB.JPG
By clamping down to the hook THEN pushing back, you pack the hair and thread wraps for a much tighter pack then you'll ever get with something more hollow. Also the Anvil is solid brass and has plenty of weight/mass behind it to really help.
Also I'll add a vote for Chris Helm, however Helm has Dozens of videos and at least 6 on deer hair. All can be found here along with dozens and dozens of there great videos.
http://www.bennett-watt.com/Fly-Fish...artments/1193/