On 2008-08-08, Randy wrote:
I was looking to buy some bore cleaning brushes to clean out small
holes, have some in .38 cal. Well I found out the larger shotgun bore
brushes have a 5/16-27 thread on them, thought this to be very
strange, the smaller ones are a standard 8-32.

Where did a 5/16-27 come from? common on other gun stuff?

Common on lamp sockets and the tubes which carry the wires to
them. I think that they were originally the thread on indoor gas
lights.

And 5/8-27 is a common microphone mount thread.

Some lathes with quick-change gearboxes can cut 27 TPI (like my
Clausing), some can not (including at least *some* South Bend lathes).

Of course pretty much any lathe with manual change gears can be
set up to cut that.

Enjoy,
DoN.

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