What are these reamers for?????

[Illinoyance]

I am going to vote for throttle shaft reamers.

[rickyb]

A friend dropped these reamers off said they were in his fathers things, he had a gun shop many years ago,
I neglected to add sizes ..371, .3695, .343, .312, .250

These look exactly like miniature versions of the in-line reamers used to ream bushings in heavy truck spindles. The pilot is smaller than the reamer diameter and is long enough to pass through the first bushing and then pilot in the second bushing as the reamer enters the first bushing. The diameter behind the reamers is the exact diameter of the reamer and pilots in the newly reamed bushing while the reamer cuts the second bushing.

measure the diameters and you will know if it is this type.

[John MacArthur]

What are their large and small diameters? Might give a clue.
Johnny

[BCRider]

Joel, barrel liners would require a larger size to allow for the OD of the liner and not the bullet bore. But you're right. I've got a liner and drill for re-lining an old 22 so I can keep the barrel markings intact. The liner needs a 5/16 hole which I have the drill with pilot for doing on hand. Still need to get "a round tuit" on that one....

The throttle bushing reaming makes a LOT more sense.

[LKeithR]

I think they're probably valve-guide reamers of some sort. Although that pilot is exceptionally long I've seen
and used lots of valve-guide reamers that were configured exactly like those the OP showed.

[Joel]

Like Andy said:
https://www.minimania.com/part/TOOL1...e-Shaft-Reamer

Not that they can't be used for any similar type of work.
What are the diameters? If they were used for pistol barrels, the diameters should match up to common calibers, no?

[andywander]

... I can't think of any reason for that much pilot length other than concerns about accuracy.

If you ever get the chance to ream some carburetor shaft bushings, you will see the reason immediately. The bushings are separated by at least an inch, and maybe as much as 2 or 3 inches.

[nickel-city-fab]

Or, (possible) custom-made reamers? Certainly they aren't in any catalog that I've seen. I can't think of any reason for that much pilot length other than concerns about accuracy.

That's possible. But Brownell's only shows piloted drill bits for doing the prep work for relining. And nothing like that long a pilot. There'd be no need even on pistols for that long a pilot.

Same with the freebore option. There would be no need or desire for as long a pilot or cut to just push the beginning of the rifling lead out a very few thousandths.

I've been looking at this stuff as part of my interest in doctoring my own firearms and the stuff I've see that does the gunsmithing jobs mentioned don't look like these. As in not even close. So I'm thinking that it's from some other industry

[BCRider]

Given the length of the pilots vs the length of the flutes, I'm gonna guess for re-lining small-caliber pistol barrels?

That's possible. But Brownell's only shows piloted drill bits for doing the prep work for relining. And nothing like that long a pilot. There'd be no need even on pistols for that long a pilot.

Same with the freebore option. There would be no need or desire for as long a pilot or cut to just push the beginning of the rifling lead out a very few thousandths.

I've been looking at this stuff as part of my interest in doctoring my own firearms and the stuff I've see that does the gunsmithing jobs mentioned don't look like these. As in not even close. So I'm thinking that it's from some other industry

[John MacArthur]

I think throat reamers too, Astro. For increasing "freebore", or distance to the rifling from the bullet, to accommodate longer bullets. https://en.wikipedia.org/wiki/Freebore
Johnny

[A.K. Boomer]

they might be for line reaming separated pairs of bushings, like those in carburetors for throttle shafts, etc.

That's a good guess id say...

[nickel-city-fab]

Given the length of the pilots vs the length of the flutes, I'm gonna guess for re-lining small-caliber pistol barrels?

[DrMike]

Hard to tell without having even a hint of the diameter or length.
Based on the "gun shop" teaser and built in pilot, I'll guess they are to ream shotgun barrel forcing cones or chokes.

[Astronowanabe]

gunsmith throat / neck reamers seem to come close but I never heard of them before

[BCRider]

Chamber reamers ?

Not that shape and length. They aren't even close to a chamber reamer shape.

One thought was for reaming out bores prior to rifling. The long forward pilot could be for ensuring a straighter run. But they aren't long enough to do any sort of rifle barrel. And I've never seen any reference to reaming the bores after a gun drilling operation. So it's a mystery...