Gunsmithing 6mm BRA freebore

[cecztayl]

Hey guys! I’m looking at having a 6bra built. Needing recommendations on freebore from the guys that have ran them.

We are wanting to run the 105-110 class bullets.

What do you think would be optimal for this? Also want to take in consideration being able to chase the lands if need be.

Thanks!!

 

[Sheldon N]

Mine have been 104 freebore, and I think that's a really common choice. Gets a 105 hybrid bearing surface clear of the neck shoulder junction and still leaves lots of neck to work with. Don't worry too much about having to chase the lands, I've only seen about 30-40 thou of throat erosion in 2k rounds.

 

[cecztayl]

@Sheldon N i was hoping to hear from you as I have found some of your posts from the past!

I seen a post from you sometime ago recommending the “Alex wheeler” reamer from JGS. Just to request a .272 neck for no turn.

Would you still recommend this or have you found another design you favor more?

 

[Sheldon N]

I'm still using the same reamer, on my second barrel with it. Been very happy with how it shoots.

 

[cecztayl]

Thanks man! I think this is the route we will go.

 

[Dlwheel]

I’m using the same reamer at .104 and no-turn neck. You’ll have no trouble with 110’s. However I’m running 105jlk’s.

 

[idahoorion]

Any donut issues?

Idahoorion

 

[cecztayl]

When you say “no turn” did you go with their recommendation of like .274-.275 on neck diameter?

Or did you go a little tighter like the .272-.273 route?

All the late Lapua Brass I have checked neck thickness has been around .0125. That should put a loaded round at about .268. I was thinking a .272 or maybe .273 neck would be a little tighter but still not require turning necks.

 

[Dlwheel]

.272. No issues with carbon rings.

 

[idahoorion]

cecztayl, Either work, if you anneal every 4-5 resizes the necks will out last the primer pockets, JME from the dasher

Idahoorion

 

[cecztayl]

cecztayl, Either work, if you anneal every 4-5 resizes the necks will out last the primer pockets, JME from the dasher

Idahoorion

Man I like it when y’all tell me what I want to hear!!!

Thanks for all the info guys!

 

[Sheldon N]

@idahoorion No issues with donuts, and the bullet is far enough up the neck that it wouldn't contact them even if they were there.

With a .272 neck and Lapua brass I'm seeing loaded round diameter at around .268 and fired brass comes out of the chamber at around .270 after springback (with mild/moderate loads). Plenty of neck clearance IMO. No harm going to .273 or .274 but don't know if it's needed.

 

[jd5521]

.104

 

[skeetlee]

more importantly the free bore diameter needs to be right. I have a proven BRA reamer and i would love to help you with your project. Lee Gardner Precision.

 

[cecztayl]

Thank you @skeetlee!
A good friend of mine with Big Buck Customs here at home will be doing the work for me.

 

[Shanerbanner10]

272 nk 130 freebore, no issue.

 

[Alex Wheeler]

The reamer that I have had the most success with, I call the 6BRA#1 and the print is available to the public through JGS. Its a .268 neck, just ask for a .272 if you want to do a no turn. It works well with Harrell's D3 BRA fl bushing sizing dies. The freebore diameter is .244" and is how I designed it. Multiple world records have been set on this reamer by my customers.

 

[cecztayl]

Hey Alex! Thanks for chiming in. I think that is the reamer I ordered.
I called JGS and told them I wanted the Alex wheeler design and requested a .272 neck. Should have it in about 6 weeks or so now.

 

[Alex Wheeler]

Yes, I only have one thats available to the public so you cant get the wrong one. Have others in testing but thats the one you want.