6 br budget build

Smokestick

Active Member
Joined
Feb 7, 2015
Messages
32
This is my first build, so I am reading all I can get my hands on, to be sure I get it right. So my question is when reaming your bore for your caliber I have read about also setting freebore at the same time, I am not completely clear on what free bore is, and pac nor factory specs. differ from those on a few articles I have read, how crucial is this, and although I will have a gunsmith do this what exactly do I ask for?
 

FearNoWind

Well-Known Member
Joined
Jul 10, 2012
Messages
2,323
Location
North Central Valley California
"Free bore" (aka throat or lead) is that portion of the chamber immediately ahead of the lands.
This diagram may help you better understand it:

https://www.google.com/search?q=rifle+chamber+free+bore&client=ubuntu&hs=jA7&channel=fs&tbm=isch&imgil=XBuF6t7Jwx3FJM%253A%253Bp6qcYwC9OYcD8M%253Bhttp%25253A%25252F%25252Fbisonballistics.com%25252Farticles%25252Fan-introduction-to-rifle-chambers&source=iu&pf=m&fir=XBuF6t7Jwx3FJM%253A%252Cp6qcYwC9OYcD8M%252C_&usg=__4gs065EvKw4moqH4GH1t_NlqcCw%3D&biw=1231&bih=927&ved=0CEEQyjc&ei=nGXjVMXuBtTnoATM7IK4Ag#imgdii=_&imgrc=aoSsn5HClt_ABM%253A%3BA7wd4PzOXui9eM%3Bhttp%253A%252F%252Fbenchrest.com%252Fattachment.php%253Fattachmentid%253D9251%2526d%253D1267208204%3Bhttp%253A%252F%252Fbenchrest.com%252Fshowthread.php%253F67906-What-does-quot-zero-quot-freebore-mean%3B370%3B242

This diagram is a bit more complex but if you understand engineering drawings it too may help you:

https://www.google.com/search?q=rif...hat-does-quot-zero-quot-freebore-mean;370;242

If you study the diagrams you'll note that the overall length possibilities for the bullet is limted to the distance from the base of the case to where the bullet's ogive contacts the lands. Once the ogive contacts the lands the bullet's OAL can't be increased. If you increase the freebore the bullet can be moved further out within the case neck. That increases case volume, decreases surface contact between the bullet and the case neck, and increases the seating depth possibilities.
Whether there's any advantage one way or the other depends, IMO, on how you want to use the rifle. But there's more to it than just free bore lengths. Lead angle (the mechanical feature that guides the bullet into the lands) is another factor to consider:

https://www.google.com/search?q=rif...Farchive%2Findex.php%2Ft-128691.html;1350;617

Are you building a hunting rifle or a competition target rifle?
 

Smokestick

Active Member
Joined
Feb 7, 2015
Messages
32
Mostly hunting, but I would love to compete a little to. There is no competitions real close to my area so, for now just building the best custom, I possibly can
 

FearNoWind

Well-Known Member
Joined
Jul 10, 2012
Messages
2,323
Location
North Central Valley California
Have you reviewed this?

6mmBR Cartridge Guide within AccurateShooter.com

When you get to this part " ... Similarly, every 6BR that I’ve dealt with will shoot 30 grains of Varget and a 105- to 108-grain bullet" don't get too excited. That load is waaaay too hot for my 6BR. I'm currently loading just 28.6 grains of Varget.
You may find, in your testing, that your rifle can handle more. Maybe not. Be sure to start low on the Hodgdon scale and work up in small increments. Your rifle will never perform precisely the same as the other guy's.
 

Smokestick

Active Member
Joined
Feb 7, 2015
Messages
32
Thanks for your help, will be a while before I am shooting but will let you know how it goes, and likely will have more questions between now and then thanks again.
 
Top