Threading barrel for chokes

[Mars1000]

Can anyone tell me where I can send a 870 barrel to have it threaded for chokes? Thanks

[Scorpion8]

Any local competent 'smith or garage mech can do it.

[BKinzey]

I second the local gunsmith. Should you question the competency just ask to see some of their work. I had a gunsmith tell me once you understand what you are doing it's not a hard job.