Machinist (?) advice needed

[drkphibr]

Have an old pump action 22 with a forend that is missing one of its screws. Searched online and actually found a place that reproduces the screw (which is supposed to fit a number of forends).

New screw looks great, nice job. Unfortunately, as you can see from the pic, the threads are about ~2 too short. The screws are about the same overall length and the threads are the correct size, but due to the screw head being much thicker/higher than the original I can't get the threads to "grab" the pump action bar threads. There is also a metal ring around the forend holes, so there is no way to remove (nor would I) any wood in the hole to account for the higher head.

Long winded way of asking what would be a viable way to shorten the bottom of the new screw head to give me back those 2 or 3 threads I need for someone who isn't a machinist (no lathe, etc.)? Just have general garage type tools.

[9mmContagion]

Easiest way is to find the correct thread size, head to the hardware store and find longer ones. Or search for longer ones online. Remember you can always cut down longer ones to the correct length (band saw, Dremel cutoff wheel, hacksaw, etc.)

[sonofeugene]

First off, if you didn't notice, the threads are different. Regardless of anything else, it won't work. You need to get the correct threads first. The new threads are coarser than the old threads.

[Barbarosa]

My local Ace Hardware has a couple of plastic bins full of gun screws. I've found many oddball screws there.

[SkyHawk]

Those threads are different for sure

Anyhow, assuming the threads did work - you might chuck the screw into a drill that is clamped into a vice, with the head of the screw exposed and the threads taped to protect them. Then run a small/thin file or emery board along the bottom of the head while running the drill. If necessary you could run the screw into something for an extension first to protect the threads and also give you some more space (for a larger file) between the bottom of the screw head and the drill chuck jaws.


Better though to get a longer screw with the correct threads. Better to have a longer screw that you can shorten, than a too short screw.

[sonofeugene]

Get one that will match the existing threads (first and foremost) and head height. Then cut the length down to fit.

[norcalAF]

As stated, a too long screw is always preferable to a too short screw [emoji16]

[Bt Doctur]

Do you know the exact thread size , brand of gun, parts listing, part number, etc

[Tarmy]

First, carefully find a nut that fits the existing screw...note the size/thread count. Now you can then hunt for the CORRECT thread/screw size...

As mentioned, too long is better...that screw has a shoulder on it too...so note that in your search.

[drkphibr]

Do you know the exact thread size , brand of gun, parts listing, part number, etc

forend screw for a Marlin model 37 pump .22. No idea on the thread size at the moment.

[SkyHawk]

Numrich shows a long and short foreend screw option. These are factory originals - both kinds are in stock. I don't see any no-thread areas on these screws though

https://www.gunpartscorp.com/products/374830

https://www.gunpartscorp.com/products/374810B

[71MUSTY]

My local Ace Hardware has a couple of plastic bins full of gun screws. I've found many oddball screws there.

This ^^^^^ Surprised me but TRUE

[sonofeugene]

Numrich shows a long and short foreend screw option. These are factory originals - both kinds are in stock. I don't see any no-thread areas on these screws though

https://www.gunpartscorp.com/products/374830

https://www.gunpartscorp.com/products/374810B

Both look like their threads are too course to work.

OP: Measure the threads. Diameter and then thread pitch. To measure thread pitch, measure from peak to peak over as many threads as you can find. Or valley to valley. Then, divide the number of threads measured. With those two numbers, even if they're not completely accurate, you should be able to determine both diameter and thread pitch. SAE or metric. Not a big deal.

[eaglemike]

forend screw for a Marlin model 37 pump .22. No idea on the thread size at the moment.

Do you have any dial or digital calipers? Measure the outside diameter, and start with that. Here is the formula for telling the screw size number:
(.013 X (screw number)) +.060 = nominal screw outside diameter
(.013 X 10) +.060 = .190 the nominal outside diameter for a #10 screw.
(.013 X 4) + .060 = .112 for a #4

Usually they are .002-.005 under that.

It's easiest to use a thread gauge for the threads per inch (or mm).

Where do you live? There's a lot of talented people on this forum.

[sonofeugene]

forend screw for a Marlin model 37 pump .22. No idea on the thread size at the moment.

The thread diameter and pitch is the first thing to find out. Then the head height/diameter/type. Then the length. For screws like that, length is measured from the underside of the head. Flathead screws are measured from the top side of the head.

Note that any measurements you get will be off a bit, based on how worn the original is and how good you are with calipers. But it should get you what you need.