Case Mouth and Neck Tension Gage 25 / 6.5mm / 7.0mm by Ballistic Tools Measuring neck diameter with calipers is an iffy proposition at best. A small burr on the case mouth and a slight angle to the calipers and or even just placing too much tension on the calipers can give distorted readings. Improper neck tension can make projectile insertion more difficult and or even cause a safety issue if the neck is too loose. Using our gage solves all those problems. It can knock off a small burr during insertion and and will not distort the round shape of the mouth like calipers will. This gage is for 6.5mm (.264) and 7mm (.284) diameter calibers. This case mouth gage is a quick and reliable way to test your neck sizing and neck tension. It is a tool I developed for my own use and I could not do without it. Order yours today.
