Accuracy testing diff powders, same session?

[Taco-XL]

I have established my most accurate loads with 3 powders.

308 Win (AR-308)
168g SMK

I have took notes and wrote down my groupings but these were small sample sizes (5-6 rounds until OCW was found). Now that I have established my OCW for the three powders (IMR 4895, IMR 4064, and Varget), I was wondering if I could load a larger sample size, say 10-15 rounds, for each powder at their respective OCW's and fire them in the same session. Assuming I'm starting with a cold, clean bore, will there be any discrepancies as far as "fouling out" the barrel with different powder types in the same shooting session? I plan on shooting each load in a 'round robin' style...one shot for each powder, then repeat. I am just wondering if different powders have diff fouling characteristics and if my method will produce accurate results or am I wasting my time? Trying to save myself 3 diff trips to the range for only 10-15 shots each.

I guess i could shoot all of one powder, let it cool, clean it, then move to the next powder, but I'm lazy and that sounds too much like work to me.

 

[Unclenick]

If you start cold and clean with each powder, you shouldn't have an issue with cross-fouling. Some match shooters say they see a bore take up to ten rounds to settle when you do that. However, most barrels benefit from a few foulers when starting clean, so I would load of few extra of the mild rounds for that purpose. How many depends on the gun. At least two, IME. Some barrels need nearer to ten, but that's unusual.

 

[4runnerman]

Assuming you are going to go to step 2 in the OCW. I don't see the need to go with 3 different powders. Your next step would be to choose one powder ( the one that performed the best). Load 5 rounds of each in .03 gn difference and fire round robin style. That will give you 25 or so rounds to shoot depending on how big your first gap was in powder charge. I guess you could do all 3 powders, but shoot one powder first, clean barrel and then do next powder. Just remember to bring a few fowler shots of each powder. Don't cross powders if not needed.