272 Nk 6BR

[Ackley Kid]

Hi guys
In loading for straight 6BR what neck clearance is acceptable? I’m asking because I’m getting random fliers . On fired cases about every 3rd one I can’t insert a bullet into the neck ....
Rifle is Bat SV with Krieger 1-8 4grove ( not sure if 236 or 237 )
Chamber is 272 no turn with 105 FB
Have been using varget 30.0-30.5 / 105 Hybrids / CCI 450
Moral of the story it’s not grouping very consistent..... good one day , poor the next
Ideas on the above would be greatly appreciated, I was thinking of skimming necks to get .003 -.0035 clearance . FYI loaded rounds are presently .2695-.2700

 

[Dusty Stevens]

Skim the necks. You may have some high spots. No turn reamers are only a suggestion

 

[Capt. Oblivious]

Id also skim them down a tad

 

[dgeesaman]

I'm running a 6BRA with no-turn neck using Lapua "blue box" brass I bought this year.

While the Lapua performs very well, the necks out-of-the box are not perfectly uniform and the loaded diameter without turning is too close to .270 for comfort. I'm skimming the necks 1x to get a .2685 loaded diameter and it cleans up the necks between 75% and 100% which is perfect for me. I recommend you do the same, even though you have an extra .001" of clearance.

 

[Ackley Kid]

Thanks guys .

 

[JFrank]

Hi guys
In loading for straight 6BR what neck clearance is acceptable? I’m asking because I’m getting random fliers . On fired cases about every 3rd one I can’t insert a bullet into the neck ....
Rifle is Bat SV with Krieger 1-8 4grove ( not sure if 236 or 237 )
Chamber is 272 no turn with 105 FB
Have been using varget 30.0-30.5 / 105 Hybrids / CCI 450
Moral of the story it’s not grouping very consistent..... good one day , poor the next
Ideas on the above would be greatly appreciated, I was thinking of skimming necks to get .003 -.0035 clearance . FYI loaded rounds are presently .2695-.2700

You may be a little hot, recommend an abbreviated ladder test to ensure your in the node as well as an abbreviated seating test , you may be experiencing extra throat erosion effecting your tune.
272 no turn neck runs good in my shop.
Just me of course

 

[Ackley Kid]

SPJ
I’ve done OCW from 28.5 right up to pressure ( 31.4 ) Also done seating depth in 2 thou increments from 10 thou in to about 30 off . I was just curious on what others run for clearance on the 6mms . Necks seem a little lumpy 13-12.2 neck wall on Lapua blue box . Bullet was 105 hybrid .... getting lots of fliers just trying to sort it out .

 

[JFrank]

SPJ
I’ve done OCW from 28.5 right up to pressure ( 31.4 ) Also done seating depth in 2 thou increments from 10 thou in to about 30 off . I was just curious on what others run for clearance on the 6mms . Necks seem a little lumpy 13-12.2 neck wall on Lapua blue box . Bullet was 105 hybrid .... getting lots of fliers just trying to sort it out .

Humm
As Dusty mentioned skimming but I just wonder if something else is going on.

I run.003 clearance / 269 loaded round without issues.

 

[jrg]

I have a 6BR with .272 Neck & .125 FB, I turn my necks to appx. 12-12.5 & my Loaded rounds are
267.5-268, I have also run .269 with no problem. I am using 107Gr, SMK @ .005 off the lands.
I tried 105 gr, Berger Hybrids, but my gun did not like them or I never found the happy place.

 

[Ackley Kid]

Thanks guys
Will try a skim cut and different bullet . I have some 107s and 105 VLD . Appreciate the help .

 

[gunsandgunsmithing]

As others have alluded to, I doubt clearance is the problem. Skimming will uniform the necks, which can't hurt but .002-.0025 is enough that you shouldn't be having problems from clearance. I like a MINIMUM of .002 and prefer closer to .003.

I hope it fixes it but I'm betting on it being something else.
Are you using wind flags? If it's a gun or load problem, those problems will usually be there at closer range, too and it minimizes the wind variable...but still, use flags always. Especially when trying to pinpoint a potential problem.

 

[jrg]

SPJ, I am running a 26"with a 7.5 twist bartlein with .272 neck & .125 FB I am turning my necks 12-12.5
& my loaded rounds are 267.5-268. I would recommend you try the 107gr. SMK with 30.0 Varget. My rifle shoots
1/4" groups @ 200 yds, before I started turning the necks I was having problems with chambering as well.
In my opinion that will solve your problem!

 

[JFrank]

Thank you

 

[lawman29]

Try some BR-4's.

 

[gunsandgunsmithing]

A .272 neck 6br is not an unproven concept. If anything, people went with smaller neck chambers (.271)when Lapua made dimensional changes to their 6br brass, which coincided nearly but not exactly with the change to the "blue box". There is and never was a problem using Lapua 6br brass in a .272 chamber. It's been done with great success a million times. Don't overthink this aspect, as it's proven to be very good. Unless Lapua has made yet another change, which the op's numbers do not support, look elsewhere. Uniforming the necks can't hurt but in terms of closing the bolt, clearance is clearance, whether it's .0002 or .002 or more, the bolt closure should be the same.

 

[jobhopper66]

^^^^There you go again Mike, injecting common sense into this discussion! LOL

 

[gunsandgunsmithing]

^^^^There you go again Mike, injecting common sense into this discussion! LOL

I'm sorry! I know that really messes up theories sometimes. Lol!

 

[group therapy]

Hi guys
In loading for straight 6BR what neck clearance is acceptable? I’m asking because I’m getting random fliers . On fired cases about every 3rd one I can’t insert a bullet into the neck ....
Rifle is Bat SV with Krieger 1-8 4grove ( not sure if 236 or 237 )
Chamber is 272 no turn with 105 FB
Have been using varget 30.0-30.5 / 105 Hybrids / CCI 450
Moral of the story it’s not grouping very consistent..... good one day , poor the next
Ideas on the above would be greatly appreciated, I was thinking of skimming necks to get .003 -.0035 clearance . FYI loaded rounds are presently .2695-.2700

might wanna try segregating the bullets. I've separated a fair amount of Bergers and every now and then, there's more than one that is like "whoa, where did that come from!!". just my .02 and good luck

 

[rhovee]

My 6BRA no turn is .272 neck.

 

[Geronimo Jim]

Bullets won't go into fired cases until the SECOND firing.