Hyper Tool added the National Twist Drill gundrill line several years back. What we liked most about their line was the Target style detachable head gundrill. The bolt-on clamping wasn't as easy as our threadlock design, but it allowed them to make a trepanning type gundrill which had the following unique characteristics:

• No dead center, hence no zero surface speed area on the cutting edge, as is the case with conventional types of gun drills.
• Rigid, sturdy shank construction to decrease torsional deflection.
• Decreased power requirements because of the "trepanning" action which decreases the volume of metal removed for a given hole diameter at a given feed with resultant reduction in thrust.

Its definitely not for cross holes or blind holes, but it will allow manufacturers with limited horsepower to drill much larger diameter holes than they thought possible. Its available in sizes from .421 to 3" diameters, in virtually any length.

For an explanation of the benefits of detachable heads, see the section on our threadlock detachable head gundrill.