Contained are STEP files for 9x19mm, 10mm, and .357SIG, and their respective chamber negatives. I've seen a lot of snapcaps around, but their accuracy is dubious, and I never see chamber negatives to go with them. I built these off of the drawings contained in SAAMI Z299.3 – 2022 for the purposes of integration into CAD projects to predict tolerances and fitment.

The chamber negatives are accurate, and so are the casings for the ammunition. The only thing that I took creative license on were the projectiles for the ammunition (as those can vary widely and are not specified), but I tried to best match conventional shapes, like 9x19mm 115gr FMJ. It is also worth noting that the ammunition data does not contain internal dimensions, only external. Internal spec for ammunition varies widely between manufacturers and is rarely indicated in public documentation. It also does not contain primer data for similar reasons, though I'd like to one day include it.

The chamber negatives are used for headspacing. To use integrate them into your model, seat the base of the negative (the wide end) onto your boltface or breech, and center it with your barrel. Of course, headspacing is a fine art, so it may take some iteration to get things right. I suggest treading on the side of caution, rather than assuming your headspacing is correct on the first go. Feel free to message me if you have any questions.