Let us design and print a gun accessory


I’m sure you all are sick of the 3D printing posts, but too bad, there are going to be a few more.

The other day I remember that some years back there was a discussion on a gun forum about a couple different bolt locks for the 10/22 which would make the gun a bolt action for use with a silencer. At the time, there were two designs that sat in between the receiver and the bolt handle preventing the gun from cycling.

Remembering this, I thought one would be easy enough to make.

First, grab the cheap crappy calipers and measure the size of the ejection port.

I’ve never been happy with this Starrett caliper, but it is plenty good enough for this case. We can see that a 0.75×0.4 inch rectangle would fit in that area.

We hop in the CAD program of our choice, type in those dimensions, and extrude it into a block.

Then lets give it a handle. We can draw a circle and extrude it out. Maybe round the corners.

Hmm, that might work, but how is going to stay in place? What about a magnet? I’m sure we all have some laying around. I grabbed a little magnet and measured it.

We could put a cut in the bolt lock for a magnet, and that would hold it to the bolt.

Ready to go. This might work.

Well, we can do even better. We gotta install and remove this thing between ever shot. Why not move the handle closer to bolt handle on the 10/22? Maybe even make it slanted so we could just pinch the handle on the bolt stop and the 10/22 bolt handle to rack the gun. I’ll just draw some lines, extrude. Then angle and size will be choose using the extremely scientific process called “wild ass guess”. And then we are all ready to print.

We export our new design with the tapered handle as an STL file. Load this STL file into our 3d printer slicer of choice,, set the settings as we want them, and have it generate G code for our printer. In this case, I set to 100% infil, and gave it a brim just to make sure it wouldn’t come loose when printing. The brim was probably completely unnecessary, but it made me feel better to have it.

Estimated 31 minute print time. Print one off, glue a magnet in, and then test it.

Yeah, I most certainly didn’t put it on the gun before the glue dried. Yeah, that didn’t happen. Un huh, no way glue got all over my 10/22 bolt.

Fits nicely.

The design works as intended. Pinching the handle of the bolt stop and the gun’s bolt handle allows you to rack the action, and then as you release your pinched fingers, the magnet pulls the stop back into place.

Perfection. End of story. . .

Well, I suppose we should actually use it.

Well damn.

This stop is has very little material around the magnet, and snapped there.

So what is next.

I could give up. Or we could beef up the stop, add more material. I could break the magnet in half and use a smaller magnet piece making it a smaller hole. I’d have to be careful to make sure I end up with a proper magnet afterwards, wouldn’t want to break at the line between poles and end up with a monopole magnet. Maybe put two smaller magnet pieces in the design in different spots.

Probably some combination of the above. There is always room for improvement. I don’t expect it would be much tweaking to get it working as intended, so I’ll end this article here.


  1. I and feel probably others are enjoying the new toy and it’s products.

    I wonder how long till it is a “restricted item” for public use.

    • I’ve been 3d printing for years, but only very recently been doing any gun stuff.
      I believe there is a good chance there will be an attempt to regulate or ban 3d printing. I also don’t see any way a ban could work or be enforced.

  2. If you manage to make a magnetic monopole, don’t forget to call Stockholm…

    Thanks – this is a neat little project to read about.

    I have to wonder … if it didn’t have the magnet hole would it break somewhere else? IOW is this a structural problem or a strength-of-materials question?

  3. Also, apologies as I think you answered this recently but I can’t seem to find it …

    What CAD software do you use? I use SolidWorks at work, but am looking for options for home use.

  4. I’m not sick of the printing posts, the real process of prototyping is interesting, and I like your assessments if time/materials used.

    Maybe a couple smaller magnets, spaced out? Maybe add a layer of metal that overhangs the printed material, acting as a spring? Maybe just print it thicker and put the magnet at the handle base with some material overlap around the magnet recess?

    Might I suggest a lanyard hole in the handle, to reduce loss if this was taken out in the field?


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