The slight degree of angle you mentioned is better known as a Straight Offset in archer terms. When fletching the TAC15
arrows the manufacturer only uses a perfectly straight fletch. This means no offset on your Bitzenburger Jig at all.
In order to achieve the proper spacing between each vane you would need to be using a special nock receiver in the Fletching Jig. It's Bitzenburger nock receiver #3012 I believe. This nock receiver when installed will provide vane spacing' of 60 degrees x 120 degrees. The standard nock receiver is only capable of spacing the vanes at 90 degrees on each vane. This will not work on the TAC15 because your vanes will make contact with your upper Weaver Rail and you'll end up with a number of problems. The optional nock receiver can be ordered directly from Bitzenburger at about $18.
Make sure you are using a premium quality fast set cement on your vanes and before starting any vane placements make sure that you pre-wipe your arrow shaft and vane base with Acetone on a clean cloth. Do not bypass this step if you want your vanes to stay on the shafts on a long term basis.
Also, once you get a very thin amount of glue on your vane and get it positioned in the clamp and down on your arrow shaft, I'd recommend you apply a small amount of extra downward pressure with your hand on top of the clamp. This added pressure forcing the vane more tightly against the arrow shaft for about two minutes will dramatically increase the strength of the bond.
By using more downward pressure with a fresh good quality glue you can change the bond strength from 200 or 300 pounds of strength to 6,000 - 7,000 pounds of strength.
I haven't lost a single vane from one of my arrows in over 3,000 shots by using the above fletching method.