I received the pin mandrels I ordered from Chad Burr, builderone, today and I am one happy camper.
I tried the 3/4" one and it works just super. I will try the other two, 5/8" and 1/2" tomorrow and I am sure they will work just as good.
These things make it so easy to turn barrels and stoppers for game calls. I really like the fact that I can change it around without having to remove the nut, washers and spacers from the 7mm mandrel each time.
Anyone who is interested in this type mandrel should contact Chad.