.2695 in a .271 too tight?

[jdw91]

Thoughts? I'm using a steel .267 bushing in a redding FL die with new Lapua brass- 6mm BR with Berger 80's and 105 VLDs.

After sizing and seating the top of the neck measures .2695 using a Hornady electronic caliper; The caliper measures to the nearest half of a thousandth i believe. I'm not sure whether it's more towards .270 or .269, but assuming exactly in between is this too tight? How much clearance do most allow? I don't have any neck turner's and the barrel is supposed to be a no-turn. It's a pretty tight bolt close but it will close.

Jake

 

[benjamin199]

Hi jake,
I will share my observations with you, other people may have different expieriences. When I tried running with only .001 clearance I would hit pressure signs at much lower velocities than when I used .003 or more clearance. Currently I am shooting a 6 Dasher with a .272 neck and my loaded rounds are about .268 (I gave them a very light clean up to .0125" neck wall thickness) this has given me the best accuracy from my rifles. I think you may need a little more wiggle room to get a clean bullet release from the case. I do not shoot BR so those guys may have differing opionions on what works best for that sport. I shoot mostly mid range F-class and have shot multiple clean 600 yard F-class targets using what I have written above.
Good luck,
Ben

 

[Preacher]

Just because a bushing is stamped .267 don't really mean that it is.........
Same way with a barrel, the chamber may not be a no-turn...
I have a .272 marked chamber on one rifle, but you better turn em or they are to tight.
Will a fired case accept a bullet with out using pressure to put it in there ???
If all your number are spot on you have enough clearance to not be a problem...

 

[GerryM]

Preachers right" Make sure you have enough neck clearance'
Better to have thinner necks and more room for expansion.
Records are being set in benchrest groups shooting this way.
Some are using a 263 and turning necks down to .008
Sized with a 257 bushing Loaded round are about 259.
Just one example.

 

[HPMike800]

Benjamin is right when he says:
"I will share my observations with you, other people may have different expieriences. When I tried running with only .001 clearance I would hit pressure signs at much lower velocities than when I used .003 or more clearance."

I have been shooting the same set up as yours and have always been velocity challanged. I started building up donuts to boot. Shot good though. You will have to clean up the necks.

 

[expiper]

Jake ..your gun will tell u what it likes.....my reamer (marked .271" NK) is prox.~.2716"....and my brass loads ~.2685" (old "hoarded" Lapua 6mmBR-circa 2005 +/-) and works great ....the biggie is watch out for donuts!! Depending on your FB and bullet combo the base of the bullet may never get in the donut area and it wont be an issue...check your seating depth that works with your particular combo.....as long as you dont push the bullet in the case more than .300" you should not contact the donut if there is one there....let us know what works 4 U....Roger

 

[UK]

J if your loaded round measures .2695 the first thing I would do would be use a 268 bushing, or even a 269 turned upside down.
once the brass has been fired 3-4 times you will need a smaller bushing anyway, 268 upside down should work before you need a 267.
you will find though if you buy the new lapua brass in the blue plastic boxes the loaded round will give you a smaller dimension as the necks are thinner, maybe better to just buy a new box of brass than mess around with neck turning kit and new bushings.

 

[Kenny474]

I think owning a neck turning device of some sort is a must if you strive for top accuracy. By turning your necks you can gain a number of advantages. Knowing the neck wall is of consistent thickness, adjusting chamber clearance, having another way of controlling neck tension (thinner necks have less strength to hold the bullet), it basically open up a whole new world of tuning options that you will never have without the turner. I turn almost all my brass simply because I can make it a consistent thickness, which also helps run-out.

You can pick up a basic tool from Sinclair for around $50, or buy a nicer, easier to adjust model for $100 or more depending on what your needs are. The better models usually cut a little nicer, but you can still get good results from most with a little practice and some patience.

 

[jdw91]

UK, interesting about just getting new brass... has anyone measured necks on the new stuff? What's the difference in diameter with a bushing turned upside down?

I'm gonna hopefully be shooting this weekend and before i forget, new shilen select barrel break in procedure? What has worked best for you guys?

Thanks to all who responded,

Jake

 

[6BRinNZ]

Hi Jake,

below is the link to the daily bulletin about the new 6BR Lapua Brass

http://bulletin.accurateshooter.com/2010/07/report-thinner-neck-walls-on-latest-lapua-6mmbr-brass/