The Home Machinist!

Anyone know what the thread pitch is on the front sling swivel mounting screw for a Remington 513T Matchmaster?
Appears to be a size 10, but not a 10-32.

Of, if anyone knows a source for a replacement, that would help too.

Steve

Measure the major diameter and then check the thread pitch. You can use a machinist's ruler to do that if you don't have the proper pitch gauge. Measure the number of threads in a given distance (¼", or ½") then multiply by 4 or 2 to determine TPI.

Harold

Google is your friend.
https://www.gunpartscorp.com/Categories ... esults=100
Hope that helps.

Harold_V wrote:Measure the major diameter and then check the thread pitch. You can use a machinist's ruler to do that if you don't have the proper pitch gauge. Measure the number of threads in a given distance (¼", or ½") then multiply by 4 or 2 to determine TPI.

The problem is that we don't have the screw, so I need to make one for an unknown threaded hole that is too small to get a pitch gauge into.

I was thinking of using some small screws to see if I can feel what size catches and what doesn't.

Patio wrote:Google is your friend.
https://www.gunpartscorp.com/Categories ... esults=100

They are out of stock, just like everyone else I have found so far.

Steve

I'm sure gunsmiths have different ways and agents which harden in the threads and can be withdrawn. I few pieces of light wood which can screw into the hole and withdrawn can clean the thread down to the root. Then a little machine oil applied to the thread with a toothpick. The next piece of wood conforms to the shape and the oil leaves a dark imprint of the tpi.

spro wrote:I'm sure gunsmiths have different ways and agents which harden in the threads and can be withdrawn. I few pieces of light wood which can screw into the hole and withdrawn can clean the thread down to the root. Then a little machine oil applied to the thread with a toothpick. The next piece of wood conforms to the shape and the oil leaves a dark imprint of the tpi.

Excellent idea. Never thought of that.

Steve

You may have looked already but did you try Brownells?

Well, I have the parts here, and the pitch using spro's method appears to be 42! Not 40, not 44!

There are special thread sizes in 40,44 and 48, but not 42.

The minor diameter of the threaded hole it does into is 0.178 (measured with a small hole gauge and verified with a pin gauge).

Using a thread calculator spreadsheet, I input the major diameter of a #12 screw (0.216) and 42tpi and it says that the smallest minor diameter of an internal thread is 0.1812, which is larger than the 0.178 of the hole.

Thought there was a possibility if was metric, and a conversion chart and Maryland Metric ( https://mdmetric.com/tech/tict.htm ) says that 0.6 in metric is 42-1/4tpi, but a chart at Engineer's Edge ( http://www.engineersedge.com/hardware/m ... sizes1.htm ) says that the only screws with 0.6 for the pitch are 3.5mm, which is too small (the minor diameter is 4.5mm)

Does it look like I'm just going to have to start threading something 42tpi and just keep taking off until it fits?

Steve

It's even worse than you thought!

.1813" is the minimum minor diameter for an external thread.

The minimum minor diameter for an internal thread would be .190".

A #11-42 would work out though, as it has a minor of .177" to .183"!

In case you want to give it a try...

Steve....did you try Sarco in Easton, PA for the parts you need? They have tons of parts and list front sling swivels for the Remington 513 T on their web site.
Sometimes it is easier to just buy a part.

Keith

Owning a lathe can sometimes cloud up the thought process.