300BlkTalk

I figured this might be the best place to post this question since it has to do with shot groups.

I've been working ladders with different powders, powder loads, bullets and ogives to see which supersonic load my rifle likes(16.5" barrel) and after about 12 different recipes I noticed that the first rounds(which is always the lightest powder load) would always give me the best groups, sometimes one ragged hole but as I worked up the ladder with more powder, the groups would get worse(up to 4" groups) for each load. Today it hit me while going through all the data that maybe I need to clean the barrel after each load and that the increase in group size might be due to a dirty barrel. I know that some of my other rifles like my 22-250 gets better as the barrel gets dirtier, to a point that is.

So any of you out there have a 300 BO that likes a clean barrel, just want to get an idea before I do more tests?

You would expect that group sizes change as you work up your ladder, so that is not a problem. To see if the barrel needs cleaned, shot a 5 shot group of your best load. Let the barrel cool and shoot another 5 shot group of the same load as before. Were they the same? If so, you have found the load that your rifle likes the best. If not, then keep testing or try cleaning the barrel and see what happens.

I like to shoot a ladder from low to high, let the barrel cool then shoot the ladder high to low. That way you see what effect that a hot barrel has on a given load when you compare the targets. If you find a load that is good either hot or cold then tour search is over.

What you mentioned is about what I do except for shooting both directions. I was just wanting to see if one or more of you have noticed if yours shoots better when clean. I know most rifles are all different but I just want to see if there was a pattern. I'm going to load up some more of my best loads and try again this time cleaning after each group plus try the cooling down method also. Thanks for your input.

BTW, after testing different bullets and brands, so far my best groups are with the cheapest bullets so far, the Sierra 110gr Varmit rounds #2110.

When I'm worrying about groups, I clean the barrel a little between strings. I try to start and stop with a similarly dirty barrel, but I don't get in there with copper cleaner or anything, just a pull through system like a bore snake, rip cord, or whatever Remington calls those squeegees. Quick and easy.

Clean when testing loads!
Dirty once I get my load developed. Clean maybe every 300-500 rounds.
Had same barrel since 2010.

I'll take my bore snake with me tomorrow and see if that helps out any. I'm retesting the best loads this time and will see if it helps, hurts or neither.

yup of course clean barrel