Good questions, @Richard300. I am sure that many have taken various routes in the quest for ultimate pellet accuracy, and there is not one list of definite steps you can/must take. Many do not bother, some only care for certain steps, some would go through some great lengths and try all the possible and already tried steps. Depends on personal preference, depends what you want to accomplish, and how much effort/time you want to put in it. I believe that there are certain steps that are very much required, because it's just physics that a pellet at 10gr vs 10.5gr will land differently at 100 yards. Same with head sizes in many cases. Some other steps may lead to diminishing returns, but those returns may not be same in all rifles. Some steps overlap, some you may want to repeat. Caution: I am far from being an expert, and I welcome comments/corrections.
To find the best accuracy, some go straight to determining the best theoretically possible pellet based on the physical characteristics of the rifle. For this you need to know what you are doing and how to do it, and have to have the equipment. They start with some very accurate barrel land/groove diameter measurements and go from there... I may go that route one day, but I will need to ask for advice for sure. For now, I go from a wide range of options available for anyone without precise equipment/expert skills...and narrow down to a few choices after taking several steps. I assume most others go this route too. Again, I am not an expert, this is just my view:
1. Clean your barrel and season it with a few shots. Make sure your rifle is able to shoot pellets with very little variation (regulated). Know your rifle, have a decent scope. Also, have a reliable chrono and a stable shooting environment (indoors if possible). Learn using Chairgun, or similar.
2. I try as many pellet brands I can find in various head sizes (if they make them). Trying to stick with dome or round head pellets for best ballistics at longer ranges, but that's not written in stone. Some pellets like certain speeds, above/below which they spiral/tumble. But this is not always specific to that pellet, because they may not tumble from another rifle at the same speed. There is a lot of info posted on what the consensus speed range is for certain popular pellets. For example JSB 18gr are said to be best between 850-930fps. Some narrow it even more to 880fps-910fps.
3. Once you narrow down to a few best pellets and the "optimum" velocity, see what head sizes work for your rifle best. They may all work within a wider range (i.e. 5.50-5.54mm) but I think that is rare for grooved barrels. Most likely the head sizes that work will be close in range (i.e. 5.51,5.52mm or 5.53,5.54mm). Smooth bore (what I read) is not that picky. Some people sort pellet heads using a "pelletgauge" costing about $40. Yrrah has a roll method that you also mentioned. Worth looking into his entire process as it also incorporates several further steps.
4. Weigh the pellets (Ebay has cheap $6-15 jewelry scales with at least 2 decimal accuracy). Use Chairgun for your distance and see where the variance in weight starts to affect the POI. After weighing, you can go back to more accurate pellet head sizing options listed in Step 3.
5. This is the step I have not done yet, but plan doing soon: get a simple die-press (Lee's cost $30 on Ebay/Amazon). Get a die: based on your barrel groove measurements or based on what head size works best in your rifle during your shootings, Order a die that is same size (i.e. 5.500) as your barrel groove/pellet head, and one that is 0.001+, 0.002+. I think the custom made dies from Lee are around $30. I plan to buy the 0.000 first until I see if it's worth to invest more.
6. After sizing with the die, go back to Yrrah roll, because I think at this point that's the only thing that would separate one pellet from another based on a possible unbalanced head or skirt or casting errors. All other variables such as weight, head size, skirt size (assume you sized that too with a die) should be the same. Again, I have never done this step, so please anyone chime in.
7. Some lube their pellets, but there is no evidence that I read that this works for everyone and everytime. To the contrary...it's a hit and miss in some cases while bullseye for others for the same pellet/rifle.
Again, this is not a definite guide. Some do none, some do some, some do all. Some do even more that I am no aware. But there are the laws of physics and some of the variables can be minimized to the point where only the shooter's skills remain as the only variable. Getting to the right velocities and constant shot strings may require that you repeatedly tune/modify your rifle.
