My pistol brass is sorted by headstamp (mostly use Winchester and Remington). I've found some of the same headstamp case OALs are longer/shorter, and fully loaded OAL's may vary by a .001" or .002", but I have never gotten any extraordinary differences (FPS) when shooting them across my chrony. Although they can be expensive and time consuming, I recommend to anyone who reloads - get a chrony, or find a friend who has one. The device really puts your work into perspective. Also, you will find that not all velocities, etc., that are in the various manuals are the same as what comes out of YOUR gun. With that said, I do use the manual information as a start/baseline for new loads, but have never went over published manual loads. I like my guns and body parts to much to chance it.

My reloading process is as follows: Scale - check the zero. I move the beam up and let it fall to the middle, move the beam down and let it raise to the middle Repeat 2x. Adjust zero if needed. Scale in use is a RCBS 5-0-5. Set the weight of the charge on the scale, and check the weight with weights from a weight set. Move beam up, let if fall. Move beam down, let it raise. Repeat 2x. If thrower needs adjusting, I will repeat the beam up/down process each time. Once my scale is set, I will throw 2 charges in a 38 special case and dump back into thrower. I do this 5x. After each reloading session, I empty my thrower. By throwing 2 charges (5x) this helps to fill all the nooks and crannies of the thrower and mechanism. I then check the loads, individually, for the first 10 rounds. Afterwards, I check every 50 or so.

As for the OAL checks and case guaging: I check the OAL on the first 5-10 rounds, then every 50 or so. I will drop a finished round into the barrel, and if it falls in, the OAL/taper crimp are good to go. I normally check 20-30 of the first hundred. After that 5-10 of the next hundred or so. A session, for me, is usually around 500 rounds.

Also, the type of powder you use may cause variations in the charge weight. I've used several types of powder (ball, large cylindrical sticks, small cylindrical sticks) and found that the ball powders and small cylindrical sticks meter very consistently (e.g., Winchester WSF/WST or Vhitavouri N340/N350) - at least through an RCBS Uniflow or a Dillon thrower. The larger cylindrical sticks (e.g., Varget, IMR 4895) don't meter through the RCBS Uniflow or Dillon very consistently, but the 4895 does meter through the Lee Auto Disk rather well. Varget is great powder but I haven't found it to meter very consistently in any of the aforementioned throwers.

That's my process, and initially it does take a little bit of time, but I view that time as being well spent, because like one poster wrote - It about how safe you can be, not how fast you can go. When I load for rifles - that is an entirely different animal. More time consuming, and not on a progressive reloader.