I understand where the gunsmith was coming from. IMO there are many rifle owners or gunsmiths that don't know enough about what they have chambered. Using SAMMI specs is a good practice if neither is as well versed as some of us loonys.
I prefer to order a reamer to suit my magazine length, and a specific brand of brass. Also prefer to consult with my reamer maker on which throat angle and length leade will work the best.
Some chamberings like the 6.5-284 have multiple versions and it would be appropriate to ask the gunowner as to which way they want it done. Some of those 6.5-284 reamers are match dimensioned and even using the wrong brand brass could get an unaware handloader into trouble with insufficient neck clearance. I know because I helped someone build a load for one and discovered the neck clearance required turning AFTER firing a few rounds and having high pressure.
Heck even Gunwerks had issues with some customers complaining about high pressures. Turns out the brass supplied from Hornady changed wall thicknesses and caught gun owners and Gunwerks by surprise. FYI Gunwerks now uses a different reamer with more neck clearance.
Last edited by Azshooter; 09/19/14.
