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Another type of counterbore?Edit

Isn't the tool that creates the angled recess for the head of a "flat head screw" also called a counterbore? That is, I don't think counterbores are limited to just creating flat-bottomed holes.

Atlant 15:14, 26 January 2006 (UTC)

To me that's a Countersink, which creates an included angle of either 82 ° or 90 ° suitable for the under side of countersunk screws such as e and f in this section. — Graibeard 20:15, 26 January 2006 (UTC)
Okay, thanks!
Atlant 20:19, 26 January 2006 (UTC)


There is definitely a distinction between a counterbore and a countersink. A counterbore has a flat bottom, perpendicular to the hole for the screw or bolt. A countersink, by contrast, is a conical recess for a flathead screw. --Dvortygirl 23:35, 15 September 2007 (UTC)

Counterbore sizing chartEdit

Could we have a sizing chart for counterbore sizes for different standard screws, or at least a reference to one here? — Preceding unsigned comment added by (talk) 18:29, 20 August 2015 (UTC)

Counterbore regarding riflesEdit

Could someone add information regarding the counterboring of rifles? A prime example being the Mosin Nagant. Counterboring a rifle appears to be a semi-common practice for certain types of rifles, depending on the circumstances of the condition of the rifles bore.

Generally speaking, counterboring is viewed dimly and will vastly decrease the value of a C&R firearm, but can be extremely useful in keeping the rifle firing accurately. I would offer up a section for this myself, but I have a very limited understanding of the specifics of how this process works, and how it can affect a weapon. If there are any rifling experts, machinists, etc. it would be helpful for others looking up firearms information. Sawta (talk) 16:24, 21 June 2016 (UTC)