Did I ruin my 6br barrell?

[lpreddick]

a .020 thous recession of the lands. you seat the bullets longer to get back into the lands at the tension you had earlier. if your powder charge stays the same then your bullet will arrive at the muzzle earlier than when lands were new. chris long's "shock wave theory of accuracy" describes a shock wave going from breech to muzzle and back multiple times before bullet exit and the wave at the breech when bullet exits gives the best accuracy. seating depth changes as little as .005, when jumping bullets, will change group size and location. the thinking here is surely the same when jamming bullets whether by .005 or deeper. you seat the bullet .020 longer with the same charge and you will alter the bullets arrival time in reference to the shock wave's position. i have always jumped bullets and noted the above. i am now seating into the lands at various depths and must adjust the previously accurate load to regain the one hole group and it does return! on copper fouling, there is the suspicion that a lot of copper fouling has nothing to do with bore roughness, since a hand lapped smooth barrel will foul, but that some copper is vaporized from bullet base due to the extreme heat and that it "condenses" when cooled...in the last few inches of the barrel. is there something here or am i all wet?

 

[nonliberal]

I thought my new barrel was toast the other day when it was really hot out. It was shooting .1s and .2s all day in calm conditions, then after I cleaned it the next 3 shot group was over 1" and the one after that was 1.5"!! I was sick, took it home and could not find any problems. Went out the next day with a box full of tools and spare scopes to isolate the problem. First 5 shot group was a .128 @ 100.

All I can figure was something got too hot the day before, never had it happen again and I didn't do anything to fix an issue. It's still shooting great.

 

[AllanR21]

I went out again yesterday morning. It was pretty humid. I used the same load. 105 HB's and N-540. For the most part, I shot excellent groups. My concern was that I had a few unexplainable flyers. I had some 4 shot in about the same hole at 200 yards and a one shot flyer about 1/2 away. Now, I'm concerned because I can't afford those flyers in a match at 500 yards. I think the post about playing with the seating depth will be my next move here. It sounds like the powder charge will have to be altered slightly to make up for this change. I've been using pretty standard powder charges for now. I'm actually thinking about bumping the charge up. I beleive the rifle can handle it. It's a Bat MB action with a Krieger barrell. Very tight tolerances, thankfully. I have never had pressure signs, ever with the current load. Any thoughts on this theory? When I load my current powder charge, it seams there is plenty of room for more powder. It looks like it might be back to doing some chrono work to see what looks good.

Thanks to all for keeping this thread alive. It has been very helpful. Any other thoughts are appreciated.

Allan.

 

[AllanR21]

Update. I guess the barrel wasn't ruined after all. I shot it in an F open 60 shot 500 yard prone match yesterday and scored a 598 35=X.

I almost scraped this barrell because of the struggle I had originally posted.

Thanks to all that gave their opinions. That's why I didn't give up on this barrell ;D

Allan.

 

[fayettefatts]

598-35x .... yea, It's junk ;D ;D ;D