Cold bore shot vs dirty bore shot

Something I noticed a long while back is that if you're shooting a heavy bullet, just on the verge of what your twist rate will stabilize, CCB's go closer to the group.

Don't ask me why that is... I have no idea. Haven't thought that much about it...

but it works in two factory Savage rifles and a Douglas barreled .243 win...

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Is it just me or does the 1 to 1.5" difference in shot placement sticks out... For your rifle that seems excessive or indicates that your barrel is over lubricated after cleaning. Liquid is non compressible and if excessive could slow your first bullet and explain the large drop.

Is this difference at 100 yards or further. I never see more than .75" off center group on 4 shots including ccb. Typically it hard to notice but on lower grains 165 I've seen the .75.

Just my input .
 
Since I posted the first question to this thread I have tried a few things. I have left the rifle seasoned with one shot through it after cleaning at the range. went back out to see how it would do. The result with a CB seasoned barrel shot; center, right on the money. I cleaned the rifle and oiled and then dry patched and one more run of a dry bore snake back through the barrel. It was a little better than what was my first result of cleaning, light oil and a few dry patches. I think the ideal of having some slight amount of oil in the barrel was causing the biggest difference. Resentally I have change powder load to Hybrid100 loading 49gr from the hodgens web sight has give me about 40fps faster and I am not overlaoding from what was spec for the 4831sc. I was running 51.5grns of the 4831. I really like the 49grns of Hybrid 100V because it is very consistant and crnograph very well. I was shooting at about 6800ft and it was 56 degrees. My ES was right at 10ft/sec on the load for 10 test rounds. So lets just say I love the load. The rest of the loads I banged steel out to 600yrds keeping Sub MOA groups of 3 shots on the steal at the different ranges. starting at 200 out to 600. I was using the drrop data from my 4831 load at 2800fps load. At 600 yrds I was shhoting high but still keeping it on the steal in a sub minute group. Really thinking about this I started knoticing the difference at 400yrds. My impact height was starting to hit a little high dut the 40fps faster volicity in the new load. But back to the original issue with the CB low shot; I think was just my own cleaning issue. I was leaving to much oil in the barrel I guess and we are not talking about the barrel being soaked but I dont think I was running enough dry patches through it. But make a long story short the best groups comes after one seasoning shot down the barrel. So for hunting season I cleaned the rifle and then shot it once before placing it in its case before the season opener. gun)
 
Although I don't remember the source, I KNOW I've seen credible testing that concluded beyond any doubt; it takes 4-9 shots to burn oil residue out of a bore. This before the bore could be considered stable in fouling. More interesting in it was that this also applied to NEW fouling from another powder type. In both cases, the tester was initially sure that reasonable efforts removed any offender to stable fouling.

My father taught me that a gun is to be put away cleaner than it was pulled. So I don't pull a gun unless I'm going to use it, & clean it either way.

To cover both concerns for barrels, I clean bores to bare metal, as verified with my borescope, after use -every time. That is, DRY bare metal. Then I prefoul with a dry burnish of WS2 and this is how the gun is stored(in a safe, in my house). All my bullets are also WS2 coated/waxed, and this is a condition of load development.
With this, my first shot is often my best.
That's where cold bore load development goes hand in hand with prefouling.
 
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