Throat movement...

[Judd]

I have shot just under a 1k rounds in my 6BR and decided I would take another measurement for curiosity sake. It has moved in .011. It's a PacNor barrel for those who might be curious.

Does this sound about right?

 

[areaone]

Do you mean it has eroded or lengthened, thus a longer throat than when new by.011?

 

[Judd]

Eroded...from shooting. Sorry, should've been more clear. This is my OAL using a modified case and same bullets I shoot.

 

[polebilly]

At 1000 rounds it sounds pretty good. One of my barrels in 6BR moved that much in 400 rounds.

 

[fdshuster]

judd: A big factor is the bullets used. Short, lightweight= less erosion. Long, heavyweights= more erosion. Your .011" lengthening sounds minimal to me, based on what I see with my 14 twist versus the 8 twists.

 

[Judd]

All good info, thanks.

More info...this is 8 twist and I've been shooting 105 Berger hunting VLD's. The previous owner shot Fowler 80's.

I thought barrel life on the 6BR was 2000-2500. Am I giving it to much credit?

 

[bugman]

Last two barrels, both kreiger, 8tw, .237 bore, 4 groove, HV.......both shot out .010 to .012...on one barrel it was @ 800 rounds, and on the other it was @ 1300 rounds. Same bullet weight, same reamer, and within 0.1-0.2 grains of the same powder brand (different lots).

Have no proof for the difference, but my best "guess" is steel quality.

IMO, 2500 rounds is very rare IF you expect match-quality results, and run them @ the upper node.

Jack

 

[expiper]

my experience is sorta like Donavans,,,,the lil bullets take more powder ,thus more bbl wear....i usually see .002-.003 per hundred rounds....in Kreiger bbls...Hart about the same ....Shilen/Lilja/Bartline .003-.004(that dont sound like much but it is aprox TWICE as quik)....Roger

 

[Judd]

So do y'all use this measurement to determine when it is time to get rebarreled or do you specifically look at groups? This is assuming you don't have a bore scope to really know what things look like.

I've learned quite a bit on this post.

 

[expiper]

Judd,,,I look for ocasional flyers,,,,the throat wears out length wise and also the bore gets much larger for the first cupla inches,,(the bbl wears out for its entire length,,just quiker and more funnel shaped at the breech)...eventually the bullets arent gripped enuff to spin correctly and they "strip" like a nut on a bolt ...and once they strip it never works rite again...the first time I had this happen I wuz oblivious to what was going on (dum kid)...now when I see the lil' sparks and lightning fling out of the muzzle I usually hear/feel the blast recoil being different,,,,some bbls look great and wont shoot and some look lousey and shoot world class....(sorta like women)...the cut bbl that I have used in the last several yrs seem to wear much betr than the button bbls (except Hart which wear very slow)...I dont know if it is d'ue to the cryogenic treatment or manufacturing methods..jsut that they wear better and shoot better/longer...Roger

 

[Judd]

Thanks...more great information! Sounds like I am closer rather than further from having a new barrel spun on.

 

[expiper]

Tom,,,you are correct,,,that is why most B"enchrest shooters want aprox .007 of jam,,,that way they dont have to worry about bbl wear during a 2 day (weekeend shoot) match involving aprox 200 rounds,,,and not have to remaesure or reset their seater die,,,,Roger

 

[johara1]

I never chase the lands, shot the same barrels all year. I may adjust the the powder charge,never the seating depth. The barrels out lasted the scope, it went south the last two matches. The same old Brux barrels will be used again. To say a barrel is done in 1200 - 1500 rds. may not be written in stone, match Quality acc. is a product of a lot of things. I think if you take care of them, they will out shoot you most of the time. I know i am the week link. ......... jim

 

[johara1]

Tom, Your right, prof on the paper. As long as it keeps shooting i leave it alone, and it did last all year. set backs seem to shoot as good or better......... jim