How to determine screw hole size & thread pitch ???

colinjw

colinjw

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I recently purchased a .22 rifle that has 2 screw holes in the top of the receiver.
( Stevens 87B). They look like they may not be factory holes.
How can I determine which screws I need to get for them ?
6-48 or 6-40 or 8-40 or even something else /
I don't have any of these screws to try otherwise I would
do that. I want to mount a scope rail .

Any suggestions ?
Thanks
 
It is easiest to determine the thread by trying known screws... get some or take it to a gunsmith.
 
If you have, or have a friend with, a thread gage, you can usually sharpen up a splinter of wood and spin it in to the threaded hole and spin it back out again, and carefully compare the threads that will be formed on the wood, with the pitches of the usual suspects to see which is closest.

Handy to have some assorted screws around to see what fits in easily, too.

Cheers
Trev
 
trevj said:
If you have, or have a friend with, a thread gage, you can usually sharpen up a splinter of wood and spin it in to the threaded hole and spin it back out again, and carefully compare the threads that will be formed on the wood, with the pitches of the usual suspects to see which is closest.

Handy to have some assorted screws around to see what fits in easily, too.

Cheers
Trev
Click to expand...

Thanks for the tip about the wood.
I have a thread gauge ( too big to into the screw hole ) so hopefully this will do it.
I think that it is a 6 size screw but not sure about the threading. i will
try this tomorrow.
Thanks
 
yukoncoyote said:
Find a couple of taps that look close in diameter and thread them in to confirm the pitch. There's only so many possible thread. Be careful if using at as it can damage existing threads if not the correct pitch.
Click to expand...

The problem with this is that if he does not have examples of different screw sizes then he certainly won't have the specialty taps used for gun smithing screw sizes other than perhaps the commonly found 10-32 and 8-32. And even then for short blind holes this trick only works if the taps are the bottoming taps. used for such holes.

Collin, if Camster is right and they are 10-32 then you're in luck because that is a size which is commonly found in the screws section of the local hardware stores. The rest of the very fine thread pitch sizes we see in gun work are specialty sizes and you will need to go to a gun shop or a gun smith to get such screws. So really Guntech nailed it when he suggested taking it to a gunsmith. And I'll add that a fair number of gun shops will tend to have the screws needed to mount a set of rings or a base to take the rings. So taking the gun around to a few gun shops would be a great starting point.
 
camster said:
Quick glance at schematic from Numrich shows 2 plug screws at (10x32)...part # 15 on schematic found here:

ht tps://www.gunpartscorp.com/Manufacturers/SavageStevensSpringfieldFox-33479/Rifles-40502/87RifleSeries-39863/87B-34288.htm
Click to expand...

Thank you for this tip.
There are 2 holes on mine just as shown in the schematic. However, they are smaller than 10-32.
I have a 10-32 tap & there is no way it can go in. Too big. The screw holes appear to be a 6.

I think that the common sense thing to do is follow the advice given.
Take it to a gunsmith. I was hoping to get the satisfaction of
doing it myself but if I try, I might screw it up ( Pun intended ).

Thanks everyone for the help.
 
Homedepot has a variety of gauges in their nuts and bolts section, free to use....just bring in the nut or screw

Might not be small enough for gun parts thoug
 
HD certainly does not have anything even close to the 6-48 or 8-40 threads that are common in firearms.

Folks, you need to realize that the fine threads suitable to very shallow blind holes and commonly found on firearms are NOT the common garden variety NF threads. They fall under the "extra fine" specialty listings. And as such we just do NOT find this sort of stuff at the local hardware stores. A gunsmith or even a local gun shop yes. But at Home Despot or Pneu Canadian? Not a hope.
 
Always like to find a new supplier. But it seems like Bolt House is pretty well industrial. The smallest and finest machine screws they list is 8-32.

Not many of us need a box of 100 screws in each size either. So one option might be a screw assortment intended for use by gun owners such as this one.

http://www.ebay.com/itm/Pachmayr-03...135063?hash=item58cf3f0217:g:DGMAAOSw6EhUQaq4

It has the popular sizes used for mounting scopes, plug screws for filling in unused holes and even saved my bacon on a couple of screws for a grip on a handgun.
 
BCRider said:
Always like to find a new supplier. But it seems like Bolt House is pretty well industrial. The smallest and finest machine screws they list is 8-32.

Not many of us need a box of 100 screws in each size either. So one option might be a screw assortment intended for use by gun owners such as this one.

http://www.ebay.com/itm/Pachmayr-03...135063?hash=item58cf3f0217:g:DGMAAOSw6EhUQaq4

It has the popular sizes used for mounting scopes, plug screws for filling in unused holes and even saved my bacon on a couple of screws for a grip on a handgun.
Click to expand...

You need to walk into the store. They sell individual pieces. Only time they didn't have what I wanted in stock was a Whitworth thread. Then hit up McMaster Carr http://www.mcmaster.com/
 
Gunneegoogoo said:
Where is a good source, in Canada, for those types of screws??

-J.
Click to expand...

Mail order from Brownells. Hey, your mail box IS in Canada, no?

Otherwise, it amounts to finding someone that has already mail ordered from Brownells, or has a stock built up over the years of spares from other gun jobs. No local gun stores? Then its back to mail order anyway.

Most of the fastener specialty stores will sell you a box of 100 as the minimum order, unless they charge a LOT for a part box that may well never move off their shelves.

If you think you may be playing with this stuff on a regular basis, order a couple of the assortment kits as well as a few taps and dies to round out the order from Brownells.

Cheers
Trev
 
An assortment would be good.
It'd last me, and my son, and his son, but hey - I'd rather have a 60$ assortment on hand than miss a range day!!!
 
BCRider said:
HD certainly does not have anything even close to the 6-48 or 8-40 threads that are common in firearms.

Folks, you need to realize that the fine threads suitable to very shallow blind holes and commonly found on firearms are NOT the common garden variety NF threads. They fall under the "extra fine" specialty listings. And as such we just do NOT find this sort of stuff at the local hardware stores. A gunsmith or even a local gun shop yes. But at Home Despot or Pneu Canadian? Not a hope.
Click to expand...

What he said:agree:
You will be lucky to find 1/4 x20 set screws and #10 x 24 if you are extremely lucky. Try finding #5 x 40 set screw .25 long. Tried 3 places in Edmonton no luck. Picked them up while visiting back in Ontario at Facca fasteners in London Ontario.
sm
 
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