The 12 is part of the "National Fine & Machine Screw" naming convention.
#2, 4, 5, 6, and so on. There is a National Course and a National Fine thread in this system. Example 10-24 and 10-32.
A number 12 diameter is 0.216" - a 7/32 is 0.2185"
a 12-40 (if you could find one) may fit a 7/32-40
but
a 7/32 -40 likely may not fit a 12-40
*the things we do avoiding work on a snowy day!
Last edited by Chill Wills; 12-12-2020 at 04:43 PM. Reason: typo repair
Chill Wills
I got my days mixed up.. I only go to the range next weekend. Which means I will have my new ammo to test!
I've also found a gunshop across town carrying a range of Eley ammo. I won't be going the online route - I'll just take a trip there to get it.
Rest In Peace My Son (01/06/1986 - 14/01/2014)
''Assume everything that moves is a human before identifying as otherwise''
Nice! Even in good times I have never been able to find the better Eley and RWS or SK in a gun shop. Just blaster rf ammo and 223's.Originally Posted by 303Guy
Number sizes are defined by a simple equation. Example #5 screw thread nominal diameter is 5 x .013" + .060", i.e. #5 nominal od(outside diameter) is .125". Actual measured diameter may be .001-.004 smaller. Usually the smaller sizes are closer to nominal than larger ones.
P.S. The reciprocal is if you know the od, the number size is the od - .060, then divided by .013. If you do that calculation and come up with a fractional number such as 6.3, it may be a metric thread.
Last edited by ulav8r; 12-13-2020 at 01:17 AM. Reason: Added P.S.
Spell check doesn't work in Chrome, so if something is spelled wrong, it's just a typo that I missed.
Thank you Gentlemen, one & all for all this technical information..."what would we do without each other? We are all Mentors to Mentors!"
One of my best friends, Harry Tobin (here) & Backyard Inventor (Y-Tube) called the other day and we talked extensively about me locating a 'variable iris' to replace my current 'eye cup' with the .050" peep hole.
I want to find a 'Lee Shaver Hadley' variable iris eye cup but they are scarce as 'hens teeth' these days.
Harry had a great idea to make inserts that would snap fit into my current eye cup...said he can print these with his 3-D printer. Geeeez, what can't those printers do anymore? Harry suggested a series of smaller iris openings for experimentation to find the size hole that'd remove that 'lint looking image' within the peep.
Here's what Harry suggested after we got all the measurements he needed from me...
Notice how it would fit right into the eye cup I have now...
I tell'Ya boys...that Harry is a genius!
If it will snap fit & stay put great, if it doesn't...well...I'll solve that little detail on the fly.
"Thank you Harry...thank you...thank you...thank you...thank you!"
a m e r i c a n p r a v d a
Be a Patriot . . . expose their lies!
“In a time of deceit, telling the truth is a revolutionary act.” G. Orwell
You might want to order the Merit #4 and see if this covers all your needs. They also have more costly options that would do about the same thing.
http://www.meritcorporation.com/products.html
#4 Hunting Disc
for Hunters $48.00
The #4 is designed to replace the existing fixed aperture in your peep sight. Our adjustable aperture allows good sighting in any lighting condition. The overall size of the disc is smaller than our target models, allowing low mounting and reduced weight. The #4 easily fits most tang sights with its standard size 7/32-40 thread. Some special threads are available for unique sights (contact us for information).
#4 Open
The #3 master disc is what I've been looking for and can't find one anywhere in stock. Merit is not taking orders right now for some reason?
It'd be nice if someone here on the CB site had one for sale!
a m e r i c a n p r a v d a
Be a Patriot . . . expose their lies!
“In a time of deceit, telling the truth is a revolutionary act.” G. Orwell
Okay. That is interesting that they are not taking orders.
Maybe the blanking covid effects them too, however I wouldn't think so? but what do I know.
The second best option: Buy extra Williams eye cups. I have not looked into it but Williams sight could supply extra eye cups. They can drilled out. Just swap them out depending on that days light.
I will tell you from my experience shooting matches in all light conditions. 95% of the time you will use the same diameter that works best and that you've settled on, and then only on the rare days will you feel the need to change for the odd condition. If you are not shooting matches, you can pick your days to shoot and in that case you might change apertures even less, I would guess.
The main thing is to establish what size is correct for you in the first place.
@ Chill Wills... Thanks, that's pretty much what Harry Tobin said & that his little invention should find that size for me pretty quickly. He is making some with the smallest of holes for a center hole for drilling of various sizes.
Williams offers only 3 'ID' sizes to choose from...
For now, I think Harry has a pretty good idea, heck...might just stick with his solution permanently if that works out.
I just want to see well enough to turn some good groups one fine day.
a m e r i c a n p r a v d a
Be a Patriot . . . expose their lies!
“In a time of deceit, telling the truth is a revolutionary act.” G. Orwell
I think you are on the right plan. Please post the inserts and how they work. 3-D printing is doing some great things I would not have thought of.
Since I don't have a friend that can design and print 3-D, I would order two more of the 0.050" disks and drill them to about .060" and .070" and swap the three as needed.
Keep shooting and try different brands and lots of ammo. The groups I posted were with CCI standard velocity $7.95/100 and the Aguila Match (Eley primed) the case worked out to right at $5 per box of 50.
Sometimes you find good lots.
keep it up.
Will do Chill Wills...this should be very interesting and a fun project for Harry and myself.
a m e r i c a n p r a v d a
Be a Patriot . . . expose their lies!
“In a time of deceit, telling the truth is a revolutionary act.” G. Orwell
Cliff Grant died quite some time back, maybe even in the 1990s. I knew him at GE in Schenectady NY. Not sure that anyone continued the business. If you were in his club, they were practically free.The #3 master disc is what I've been looking for and can't find one anywhere in stock. Merit is not taking orders right now for some reason?
It'd be nice if someone here on the CB site had one for sale!
Thanks for that information Martin Luber... I had no idea. These may be impossible to find now.
a m e r i c a n p r a v d a
Be a Patriot . . . expose their lies!
“In a time of deceit, telling the truth is a revolutionary act.” G. Orwell
When enlarging an aperture it will work better if you are able to drill to size then enlarge from the front, leaving a sharp edge at the back end.
Spell check doesn't work in Chrome, so if something is spelled wrong, it's just a typo that I missed.
Well had a good conversation with my buddy OS OK the other day and just trying to lend a hand for what he’s trying to do. As for me I’m a handgun shooter, so this is all new to me. But I do like making things and figuring out problems. Now OS OK thought he wanted to go smaller for the sight, so thought I could make some inserts for it. I started tonight on it and got a few made up, so I did some with a long shroud and some with a medium shroud and just a disk. And for these I’ll cut a .040 hole and some with a .046 hole. That’s what he thought he wanted to go smaller. Now I can print these out but found they are slightly out of round so I made them over sized then I can chuck them in my lathe and true them up. So this is a fun little project for me, so if it works great if not it was something to do. Now in my original sketch I had a tapered relief for the hole as I thought about it thought it could cause a reflection. Instead I just did an inset straight down. So here’s my progress on this project.
Armed society is a polite society
Live A Little Learn A Lot
That is sooooo cool Harry...I appreciate this very much & they look great. Can't wait to try them out, you might have started something new that'll catch on in this shooting dicipline where folks could have a kit of assorted inserts like this and that shroud, I think will be a winner too. We'll see soon. Thanks again Harry!
PS...I may have found the #3 Merit Master Disc right here in forum, I'll know soon.
a m e r i c a n p r a v d a
Be a Patriot . . . expose their lies!
“In a time of deceit, telling the truth is a revolutionary act.” G. Orwell
Small variable iris's (?) are available for not much money if you don't mind waiting for the slow boat from China. I have bought a few of these in various shapes and sizes and all work well.
The advantage of an iris is that you can change it to suit the current light conditions, adjust the same way you would with a 6 hole aperture, keep stopping down until you start to loose light then come up one stop.
https://www.aliexpress.com/item/1005...archweb201603_
Here's my 3d printed precision pistol shooting specs with one of these iris fitted.
Amazing the technology today! Thanks for that link, I gott'a show that to Harry Tobin, he shoots like you do....and great shooting by the way!
I can get those 'tight groups' too but the dang muzzle blast sets the target on fire before I can get a good picture!
a m e r i c a n p r a v d a
Be a Patriot . . . expose their lies!
“In a time of deceit, telling the truth is a revolutionary act.” G. Orwell
Yes! Master of the one shot group.
Good one!
Rest In Peace My Son (01/06/1986 - 14/01/2014)
''Assume everything that moves is a human before identifying as otherwise''
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