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6mm BR build

 
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  #1  
Old 09-21-2013, 07:19 PM
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Join Date: Jul 2011
Location: Bend Oregon
Posts: 91
6mm BR build

I really want to say thanks for all the great feedback I get on here,

I was considering a 6mm BR build and was going over some of the details,Ive decided to go with that caliber , but was considering the advantages of going with a tight neck vs a no turn neck, considering the quality of the brass today any thoughts on whether the gain in accuracy with turned necks is worth the effort ?

Also concentricity gauges, 1 are they also worth the cost and effort ,any practical accuracy gains ? if so which one do most folks going with these days, I see Horaday has one that can "correct" concentricity anyone have feedback ?

I just bought a Forster bump/neck bushing die, have only used the expander ball type dies thus far, Ive been reading about these ex pander mandrels , are they only used with neck turning or could one use them when neck sizing with bushing dies ?

regarding "donuts" how to avoid / correct them when using bushing dies ?

Thanks in advance Scott
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  #2  
Old 09-22-2013, 06:16 AM
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Join Date: Dec 2005
Location: Tucson Az
Posts: 1,294
Re: 6mm BR build

I suggest you read all you can on the 6 BR here:

6mmBR Cartridge Guide within AccurateShooter.com




At the bottom of the article they have frequently asked questions. One is titled: tight neck/ turn or no turn neck:

NOTE: they prefer LAPUA brass and suggest the reamer has dimensions that work best with that brass. If you are serious you will have your own reamer made. I think it is a very important aspect to creating an accurate rifle. It is well worth the $140. I use Pacific Tool and Gauge. After reading the articles you can call Dave Kiff and discuss the dimensions on YOUR reamer.

You won't get donuts if you don't turn the necks. Or if you turn the necks and do it properly you shouldn't have a donut either. The trick is to cut a portion of the shoulder when you turn the necks.

From the tight neck/no turn article in frequently asked questions:

"The collective wisdom is evolving on this issue. Originally, 6BR shooters emulated what works for the 6PPC–tight .262″ necks with a .009″ or so neck wall thickness. Now the trend is in the other direction. Many shooters have had great success with .268-.269″ necks that allow full neck uniforming with a cut up into the shoulder to block the formation of doughnuts. That said, we are now seeing very accurate rifles being built with .271-.272″ and even .274″ chambers that allow Lapua 6mm BR brass to be loaded and shot with no neck-turning. The results have been encouraging to say the least. Richard Schatz recently set a 1000-yard world record with a .271″-necked 6mm Dasher. And there is evidence that the longer VLD bullets work best with the greater neck tension allowed by unturned or minimally-turned brass. One well-known shooter says he has seen no loss of accuracy since changing to no-turn necks, and that’s how he will chamber all his future barrels. However, most top smiths still recommend turning necks, but not down to .262″. A .269″ chamber appears to be a good compromise, allowing a quick, easy one-pass turn without sacrificing beneficial neck tension. For a varmint or tactical rifle, the choice is clear, however–go with a no-turn neck so you can spend more time shooting and less time reloading. Both the Lapua and the Norma brass are good enough that you will give up very little accuracy."

There are many articles on the 6BR here, enough to keep you busy for hours.


As to the bushing dies. I prefer Redding S bushing die and a separate body "bump" die. The combined FL/bushing die doesn't allow the flexibility IMO.

I have used this concentricity gauge and really like it:

SINCLAIR CONCENTRICITY GAUGE | Sinclair Intl

Read all those articles and register on forums at that site. You will get a wealth of information from the best BR site on the web. Forums:

SHOOTERS' FORUM - Index

I am certain you will hear from others here. Good luck on your quest.

Ross
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  #3  
Old 09-22-2013, 10:25 AM
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Join Date: Jul 2011
Location: Bend Oregon
Posts: 91
Re: 6mm BR build

thanks for the feedback Ross, when you are using your concentricity gauge, what do you do with the round that have too much runout? do you just use them for foulers. or is there a way to correct them ?

also with this are you measuring both brass necks and loaded rounds ?

thanks again Scott
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  #4  
Old 09-22-2013, 10:49 AM
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Join Date: May 2008
Location: South of Canada and North of Wyoming
Posts: 5,954
Re: 6mm BR build

Quote:
Originally Posted by D Scott View Post
thanks for the feedback Ross, when you are using your concentricity gauge, what do you do with the round that have too much runout? do you just use them for foulers. or is there a way to correct them ?

also with this are you measuring both brass necks and loaded rounds ?

thanks again Scott
Develop hand loading techniques and use equipment to consistently produce concentric rounds. I find that FL dies produce the most concentric necks. If sized down much smaller than the expander, the expander might induce some runout. Lubing the inside of your necks will reduce or eliminate that. The best thing to do IMO is to have a custom die made to your chambers specs and have the neck portion made so it only reduces the ID to 1 or 2 thou less than the expander. Some use FL dies without ex panders, but I think ex panders eliminate any irregularities inside the neck.

Use a seating plug that best matches your bullets ogive and learn how to seat producing the best results. Using a concentricity gauge during the sizing and seating process will show you what is not working and what works best. I find that starting the bullet into the neck then backing off and turning the bullet about 180* helps get better results. Also, I work the sizing and seating strokes slowly.
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  #5  
Old 09-22-2013, 01:20 PM
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Join Date: Feb 2006
Location: az
Posts: 2,252
Re: 6mm BR build

D SCOTT - what rifle? scope? what are you shooting at??
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  #6  
Old 09-22-2013, 02:53 PM
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Join Date: Jul 2011
Location: Bend Oregon
Posts: 91
Re: 6mm BR build

I have 2 NF, one is a BR 12-42, other is an NXS 5.5-22x 56
I will either re barrel my savage LRP into this 6MM or build up a benchrest/varmit rifle, off either a Farley or Viper action, I shoot mostly at steel long range,varmints, here and there, no big game hunting
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  #7  
Old 09-22-2013, 02:55 PM
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Join Date: Sep 2010
Location: New Zealand
Posts: 321
Re: 6mm BR build

Quote:
Originally Posted by roninflag View Post
D SCOTT - what rifle? scope? what are you shooting at??
Would be interesting to know your rifle spec
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