https://4drentals.com/product/12-gauge-rem-choke-tap-reamer/

I used a hacksaw and this on my 870 turkey gun project. Worked great, squared the shoulder on my less-then-perfect cut. Might be an option if you're interested in DIY. Good luck.

Last edited by MonkeyWrench; 12/02/21. Reason: Posted link without explanation
The Rifle is the Weapon of Democracy