metric thread??

[hiram]

I have a tang sight which I think is made by Persoli. I bought it from Jeff's Outfitters. I want to make a new aperture with a slightly larger hole. I do not want to alter the one which came with the sight. The thread is very clsoe to
12X40 but doesn't quite make it. Is this a metric thread and does anyone know what the size is??

Thanks

[Lee]

Observations; These Pedersoli guys make many different tang sights, with many apparently different thread sizes. And they ain't alone. Marbles and others also make tang sights, it "appears" there are several different thread sizes available for the aperture disc.........

I have two different tang sights on reproduction Pedersolis' that I own, I believe both are made by Pedersoli.

One has a thread size which is close to 5mm or 10-32 and Brownells sells apertures which will fit (at least well enough that you will be satisfied with the results!!) for $8.00 (I know that, just received them yesterday) They are 3/4" disc diameter, if that is not a problem, and a real quick solution to your question.

The other one has a thread size I can not identify, although it appears to be a 6-40 (or whatever the "he@#" the closest metric equivalent size to THAT is.
I am currently in a casual contact with a gentleman who advertises apertures on ebay, who can do "semi-custom" jobs for a reasonable price(say $10 or so depending on complexity). If you are unable to find his ebay ads, let me know and I can PM you his email address.

Hope this helps............................................. .......Lee:)

[hiram]

Thanks for the info--I'll check brownells.

I have a tool shop that has the metric stuff. I'm checking them out.

[gzig5]

Hiram,
The thread on most US made sights such as Lyman and Redfield is 7/32(5.6mm) x 40. I've made these before and it is pretty straight forward if you can thread in a lathe. Check Brownell's as they give the specs on most of the aperatures. I see there is also a 10-40 for the Browning 1885. Good Luck.
Greg

[Chicken Thief]

12-40~5,5mm-0,5mm (5,5mm thread with 0,5mm pitch) mm fine thread
10-32~5mm-0,8mm mm standard thread
6-40~3,5mm-0,6mm mm fine thread

Here's answers:
http://mdmetric.com/thddata.htm

Hope it helps.