My two 45 lb reflex defiex longbows both tune with a 400 spine shaft and a 200 grain total up front. I use a 100 gr stainless insert from ethics archery and a 100gr broadhead or field point. Bare shaft will tell you how close you are with the spine. I needed the extra weight up front to weaken the 400 a bit to get it to tune. I did not want to cut my arrow shafts so use weight to get the spine to tune.
You can also get the test kit from ethics which is different weight target points and use the stock aluminum inserts that come with the arrow shafts to find your best flight bare shaft.
