A 23-gauge headless pin has a diameter of 1/64″, which makes it about 22% smaller than an 18-gauge nail, and it’s about 10% smaller than a 21-gauge pin.

The choice of filling the holes is up to you. On light coloured wood I usually fill the holes. I find that on darker woods the holes show up much less, and the finish further helps to obscure them.

I use a 23-gauge pinner to fasten narrow lightweight mouldings, face trim on panels, dentil blocks, and irregular shapes that are awkward to clamp. One of my favourite uses for a pinner is holding stock together during glue-up. Invariably, when you begin applying clamping pressure the pieces begin to shift slightly. Pinning the pieces together before applying the clamps does a good job of keeping the pieces from sliding around. Likewise, I use a pinner, rather than tape, for attaching narrow edge trim on panels. You’ll still want to use glue, but the pins will provide enough pressure so that, in most cases, you can dispense with clamps. In fact, you can use pins in most situations where you would use tape to hold small stock during glue-up. I also use a pinner in place of double sided tape when making templates. The pins hold the template firmly in place, yet the two pieces can be separated later on.

Because I use a pinner intermittently – picking it up, putting it down – and rarely holding it for longer than five or ten minutes at a stretch I prefer one that is compact and light in weight.

The new Milwaukee M12 23-gauge pinner (#2540), a runner up in the power tool category of the 2021 Tool of the Year Awards, fits the bill and then some. It’s available as a tool-only for those who already have an M12 battery charger and an M12 battery , and in a kit that also includes a charger, 12V 1.5Ah battery and carry case.

With battery installed the Milwaukee 2540 weighs just 3 pounds 12 ounces, and measures a scant 7-1/2″ head to heel, making it the lightest and most compact pinner on the market. Compared to the cordless 23-gauge Ryobi P318VN it’s almost 1-1/2 pounds lighter and almost 3″ shorter.

You can shoot pins from 1/2″ to 1-3/8″ long. I almost always use 1″ pins, but it’s nice to have the option for longer pins should the need arise. The magazine holds a single strip of 100 pins, and I found it very quick to open and close the magazine.

You need some way of knowing when to add more pins. With the 2540 you can just keep shooting right down to the last pin until the lockout feature kicks in and the driver automatically stops firing.  There is a second way to know when to add pins – the small status window on the side of the magazine. Looking through the window you can see when the magazine is nearly empty.

The 2540 comes with a no-mar tip that helps to protect delicate surfaces from being scratched. Sooner or later though, the tip will wear out or you’ll loose it.  Milwaukee has thoughtfully stored a second no-mar tip right on the pinner (next to the hex wrench on the side of the magazine). The no-mar tips have alignment guides integrated into their top and sides that enable you to precisely line-up your shots. I haven’t found much of a difference using the pinner with or without the no-mar tip when working on hardwood, but I do use it when working on softwoods and pre-finished sheet goods.  Line of sight down the front of the pinner is also excellent, making it easy to place pins accurately.

I always leave the pin depth adjustment wheel at it’s maximum setting so that pins are set just below the surface – I don’t find it makes a substantial difference whether I’m pinning into hard or soft woods.

On both sides of the 2540 rubber pads are strategically placed to protect the pinner when set down on a work surface.

I haven’t encountered any jammed pins using the 2540. But, if a pin does get jammed all you need to do is remove  two bolts, loosen a third, slip off the cover plate, and remove the errant pin. The striker blade is made of hardened steel, so should last a lifetime.

To fire the 2540 you depress a safety level in tandem with the firing trigger – a nice safety feature. Each time you pull the firing trigger it shoots a pin. Unlike some pneumatic pinners there is no actuated tip – there doesn’t have to be any contact with the work piece for the trigger to fire. And, there is absolutely no ramp-up time when you pull the trigger.

Just above the nose plate cover is an LED work light that comes on every time you depress the safety lever. Its a convenient feature to have if you’re working in dim light.

The 2540 also features a reversible belt hook. If you use the pinner exclusively in the shop, then you can remove the hook; otherwise, it’s a convenient feature to have on a job site.

Power is delivered from a 12V 1.5Ah battery. You can easily sink five or six pin strips with this battery. I’ve had no problem sinking 1-3/8″ pins into ash side and end grain. If you want a longer runtime you can upgrade to either a Milwaukee 12V 3Ah (#48-11-2430) or 6Ah battery (#48-11-2460) that will give you oodles of extra power (though at a higher weight for the 6Ah battery).

The Milwaukee 2540 is a professional grade, sturdy, well-designed pinner that gives you the performance and power of a traditional pneumatic pinner without the hassle of an air hose or compressor. It uses a nitrogen gas spring mechanism – essentially a sealed nitrogen-filled tank creates pressure that drives the striker blade – a very dependable system that’s widely used by other battery powered pinners.

It’s about as perfect a pinner as you can get for precision fastening of narrow, thin or delicate stock.