How much freebore in 6BR for light weight bullets?

[Lefty Trigger]

Thinking of having a slow 12 or 14 twist 6BR barrel made to shoot light weight bullets 70-80gr. Barrel maker wants to know freebore needed.

 

[Eric Leonard]

.050

 

[BoydAllen]

Depends on the bullet. For 55 gr. varmint bullets I suggest a zero FB, for typical short range benchrest bullets, something between .040 and .060.

 

[NorCalMikie]

How much? ZERO!! And 70 or 80 grain arn't "lite" bullets. Zero freebore, no turn neck, start with 45 or 50 grain bullets stuffed at or into the lands.
Go heavier as the throat wears and it will. Sometimes sooner than you expect. Don't like a zero freebore? You CAN make the freebore longer but you can't shorten it without doing a re chamber. Plan ahead.

 

[dolek]

How much? ZERO!! And 70 or 80 grain arn't "lite" bullets. Zero freebore, no turn neck, start with 45 or 50 grain bullets stuffed at or into the lands.
Go heavier as the throat wears and it will. Sometimes sooner than you expect. Don't like a zero freebore? You CAN make the freebore longer but you can't shorten it without doing a re chamber. Plan ahead.

OP said 70-80 range, nothing about 45-50 grain bullets so Zero Freebore is not wise .

 

[swadiver]

.060" to .085"

 

[jackieschmidt]

I use a .060 for 65 and 80 grn Bart’s.

 

[expiper]

I have been shooting short range BR with BR's since the 70's and have two reamers,,,the .040" FB has worked well with every 70 gr and lighter ((Euber-Fowler-Hammons-Watson-Conway-Hoppe-Hottenstien-Bart-Berger)) bullet,,my other reamer is .100 FB which has proven to be perfect for the 105 class bullets,,,Roger

 

[Boatschool02]

search "6br freebore photos"
I did a long write-up.
Highly recommend thinking in terms of length and boat tail (or not) instead of weight.

 

[NorCalMikie]

Thinking of having a slow 12 or 14 twist 6BR barrel made to shoot light weight bullets 70-80gr.

OP said 70-80 range,

And I said 70-80 grain bullets are NOT lite bullets. And the OP says he's THINKING of having a 6 BR built. My suggestion???....
So when the throat is WAY gone, what do you do? Go to 100=120 grain bullets?

 

[dolek]

And I said 70-80 grain bullets are NOT lite bullets. And the OP says he's THINKING of having a 6 BR built. My suggestion???....
So when the throat is WAY gone, what do you do? Go to 100=120 grain bullets?

Sweet story bro.

 

[Murray Brook]

Had a 10 twist 6br built last year, went with 0 freebore. Even with this the 64 gr Berger is only appx .183 into the neck touching the lands and the lighter bullets even less.

 

[NorCalMikie]

I load all my rounds into the lands so, ZERO freebore works best for me. YMMV.
I also prefer as much bullet/neck contact as I can get.
First off the shelf 6BR barrel had way too much freebore so lighter bullets had to jump to the lands. Sold it off to someone that wanted to shoot heavy bullets.
From that point on, I order chambers cut to MY SPECS.
Lite bullets stuffed .010 into the lands and I have dumped powder into the chamber when pulling a loaded round but I knew what to expect. Easier to keep it clean that way. I bench shoot so a jam is what works best for me.

 

[Lefty Trigger]

I have been shooting short range BR with BR's since the 70's and have two reamers,,,the .040" FB has worked well with every 70 gr and lighter ((Euber-Fowler-Hammons-Watson-Conway-Hoppe-Hottenstien-Bart-Berger)) bullet,,my other reamer is .100 FB which has proven to be perfect for the 105 class bullets,,,Roger

I know my 105gr class barrels are .104, never messed much with the lighter bullets but a few guys in our club have built rifles this year and are killing it with Sierra 70gr SMK's. I was going to try some in my 8 twist barrel but after doing a lot of reading I think I should lean towards a 12 or 14 twist but those are not so easy to find nor a smith that has a shorter freebore reamer. I think my barrel maker has a .085 on hand but no barrel blanks in slow twist.

 

[Lefty Trigger]

I load all my rounds into the lands so, ZERO freebore works best for me. YMMV.
I also prefer as much bullet/neck contact as I can get.
First off the shelf 6BR barrel had way too much freebore so lighter bullets had to jump to the lands. Sold it off to someone that wanted to shoot heavy bullets.
From that point on, I order chambers cut to MY SPECS.
Lite bullets stuffed .010 into the lands and I have dumped powder into the chamber when pulling a loaded round but I knew what to expect. Easier to keep it clean that way. I bench shoot so a jam is what works best for me.

What twist rate do you use for the light 40-50gr bullets then? I kinda like the idea of shooting lighter and as it wears going a little heavier. I have a 6BR barrel now that still shoots good but even 105's fall out of the case at the lands, probably over 4000 rounds.

 

[NorCalMikie]

Like I had mentioned earlier, had one "off the shelf" barrel that I couldn't get close to the lands. Shot good but just wasn't to my liking. Sold it to someone that wanted to shoot heavier bullets.
Did LOTS research and ended up with a PacNor 8 twist straight pipe in SS with ZERO freebore and a no turn neck. 50s touching the lands with LOTS of bullet/neck contact.
BT slightly down into the shoulder area but not into the powder charge.
Flat base bullets just at the shoulder neck junction.
Found that a jump to the lands would start showing pressure at a given powder charge BUT, that exact same load (powder/bullet) with the bullet jammed into the lands wouldn't show pressure and I could even bump up the charge with no Ill effects. The longer we're at it, the more we learn.
AND,what works for me may not work for you so keep that in mind.

 

[swadiver]

I know my 105gr class barrels are .104, never messed much with the lighter bullets but a few guys in our club have built rifles this year and are killing it with Sierra 70gr SMK's. I was going to try some in my 8 twist barrel but after doing a lot of reading I think I should lean towards a 12 or 14 twist but those are not so easy to find nor a smith that has a shorter freebore reamer. I think my barrel maker has a .085 on hand but no barrel blanks in slow twist.

70gr SMK is a very underrated bullet. shoots awesome in a 13.5 twist Krieger 6BR with a .045" freebore. shot a .015" five shot group with this rifle using N135

 

[Ackman]

If you're talking about "light" bullets, that's 55-70gr. Go ZERO freebore. The 6BR case has a long neck. In my 0 freebore gun, a 55gr. bullet seated just shy of the lands is exactly 1/2way down the neck. A 70TNT is .100" above the neck base, and a 70Ballistic tip is .050" above the neck base. They all shoot really! well in a 14twist barrel. You'll be fine with 0 freebore.

 

[AckleymanII]

I think that a tad bit of freebore is a good thing. I have a zero freebore reamer and touch it up with a unithroater for a .020 freebore. A tiny bit more freebore gives me a warm fuzzy feeling looking at it in the bore scope. H335 and AA2230 gives unbelievably long barrel life with bullets up to 75g shooting barrels real hot on p. dog towns. Much easier clean up than the 322 versions also.

The 6 Dasher and 6 BRX are monsters with these lighter bullets using H335 and AA2230 with zero to .020 freebore. 55's at 4100 in a 27", 12-14T are the norm....beats a 220 swift and 22/250 AI!

 

[Lefty Trigger]

Nobody seems to have slow twist barrels and if they do that dont have a 0 freebore reamer or just flat out dont want to fool with it. To keep me shooting I ordered another 6,5x47 Lapua barrel from Shaw, was instock and shipped today so that will give me something to play around with till I can get a BR barrel found. Northland told me that Shilen is the only company they deal with that has that reamer but they are 20-25 weeks out! I'm 9 weeks in on my 7mm BR barrel now and its driving me nuts waiting. Just got a crap ton of 70gr Sierra match kings and Berger 80gr flat base bullet in,... just no barrel for them... Grrrrr.