Regardless of the selection of an IR gun or contact probe pyrometer they must be calibrated at least annually. IR guns, As long as you get a good one such as the Fluke 561, have a very good range, up to 999°F I believe, and can be used from very close range to several feet away which has many advantages.
Remember, most preheat and interpass temps are MINIMUMS but under some codes you will also need to watch your maximum limits. And, as you mention, accomplishing all the data recording for the PQR is more exacting than can often be accomplished with Tempilstiks, even with the whole set which is a little expensive.
Hopefully Al or one of the others will pitch in and offer some more complete advice.
He Is In Control, Have a Great Day, Brent
Temp Sicks are great, but terribly inaccurate and often used incorrectly so supply misleading info.
IR Laser devices are extremely handy, but again can supply misleading info, especially when reflectivity is an issue. I've seen 100 F differences an inch apart of the same piece of steel, depending on if the laser point was on mill scale or a grind mark.
IR Thermometers and contact pyrometers are best for critical functions when accuracy is a must.
Tim