6br a study of the zero freebore

[cj8vet]

freebore tutorial please
--where does this measurement go to/from--I know ogive is one but?? zero freebore seems like it ought to have the ogive at the case mouth-help ? pics/diagrams?
Thanks
Mark

 

[urbanrifleman]

Would you mind sharing which powder that you’re liking with 70 grain and under bullets in the BRA?

LT32 should be the BOMB.

 

[urbanrifleman]

What twist are you using with your zero freebore 6br TKS

Mine is 13.5 but my next one will be a 12 so can shoot 80 BTs.

 

[urbanrifleman]

The 55 blitz is the most explosive I have found so far.

The 80 Blitz hits like a hammer.

 

[Alex Wheeler]

freebore tutorial please
--where does this measurement go to/from--I know ogive is one but?? zero freebore seems like it ought to have the ogive at the case mouth-help ? pics/diagrams?
Thanks
Mark

A zero freebore means the throat (the tapered section) starts at the end of the chamber. There is some extra chamber length and a chamfer, so even a zero is still more like a .020-.030 from the actual case neck. And the ogive does not contact at the very start of the taper usually, so thats why you see the bullet hanging out more than you would expect. If you had some really short bullets like you see in the .22 cals you could go to a 2 degree throat to help get more shank in the neck.

 

[urbanrifleman]

The 70 TNT explodes like a grenade. BTW and man, do they shoot. Shockingly so... They shoot only marginally worse in my rifles than the Barts Avenger, maybe a 1/8 minute worse with no flyers.

 

[gunsandgunsmithing]

A zero freebore means the throat (the tapered section) starts at the end of the chamber. There is some extra chamber length and a chamfer, so even a zero is still more like a .020-.030 from the actual case neck. And the ogive does not contact at the very start of the taper usually, so thats why you see the bullet hanging out more than you would expect. If you had some really short bullets like you see in the .22 cals you could go to a 2 degree throat to help get more shank in the neck.

Well said. I had a guy asking me the same question just yesterday. I did my best to explain exactly what you just said but I'm not sure he understood, still. I failed to mention the 45° angle at the end of the chamber. Another small factor is case length vs actual chamber length, ie trim to length. I think people just have a hard time visualizing it but it's not complicated, just a tad confusing. Nobody ever wonders about it when you say it has, say .188 freebore, for example. Just zero. Lol!

 

[Murray Brook]

Mine is 13.5 but my next one will be a 12 so can shoot 80 BTs.

Would you think a 10 twist would be to fast...

 

[urbanrifleman]

Would you think a 10 twist would be to fast...

For a zero freebore I would think 13 is optimum but 12 lets you shoot 80s. Ten twist if you have it should shoot good up to 90 grain.

 

[urbanrifleman]

I would use the standard 104 for ten twist unless you want to shoot the 55s

 

[Murray Brook]

I would use the standard 104 for ten twist unless you want to shoot the 55s

I was thinking of shooting the lighter bullets and as the throat gave way to erosion I would be able to move up to the longer ones in an effort to get a better round count. Just not sure if the 10 twist would be to fast for the lighter ones.

 

[urbanrifleman]

I was thinking of shooting the lighter bullets and as the throat gave way to erosion I would be able to move up to the longer ones in an effort to get a better round count. Just not sure if the 10 twist would be to fast for the lighter ones.

Nah. It is not ideal but my 10 twist 243 shoots the 70 grainers lights out even at 3800 fps.

 

[Murray Brook]

@urbanrifleman
What barrel length are you using/reccommend in your 6br. TKS

 

[urbanrifleman]

@urbanrifleman
What barrel length are you using/reccommend in your 6br. TKS

My zero freebore is a 13.5 Kreiger HV at 26 inches. My next one will be a Bartlein or Rock Creek 1-12. My Kreiger barrrel shoots. I had no idea how well it is shooting until I started comparing it to guys shooting the PPC that post here. My 6BR will hang right with them I think.

If you have a Remington 700 I just sent my 6br zero reamer to my friend Paul Craddock and he is going to make some 1-12 Bartlein prefits if you want one. His barrels shoot insane good.

 

[Murray Brook]

@urbanrifleman
Thanks for the info and offer, but I live in Canada and to get the barrel across the boarder would be a paper work nightmare and a very expensive export permit. There is a barrel maker up here that makes great barrels. ( J C Custom) TKS

 

[Eric Leonard]

80 Berger in .104 fb 6BRA

 

[urbanrifleman]

View attachment 1147694 80 Berger in .104 fb 6BRA

104 works great for that Berger 80.

I am having a 50 fb 6bra reamer made now.

 

[Brians356]

The 70 TNT explodes like a grenade. BTW and man, do they shoot. Shockingly so... They shoot only marginally worse in my rifles than the Barts Avenger, maybe a 1/8 minute worse with no flyers.

Speer TNT is all I shoot now for varmints, and they are so inexpensive. I shoot them in 223 (50), 6mm Rem (70), and 250 AI (87).
-

 

[urbanrifleman]

Speer TNT is all I shoot now for varmints, and they are so inexpensive. I shoot them in 223 (50), 6mm Rem (70), and 250 AI (87).
-

My last pdog hunt all I shot was 50 tnts and 70 tnts.

 

[Mark W]

I shoot a lot of 70 Gr TNTs for cheap 100 and 200 yard practice, but 70 Gr Blitzkings show a distinct advantage in the prairie dog fields. The sound of a solid hit is even more satisfying with the BKs.