need advice on 284 reamer

[Julien]

My plan is to build a 284 to shoot 180gr brgers, and I want to use lapua brass .
My question is what freebore length and diameter should I go for to have the bullet shank boatail junction just ahead of the Neck shoulder junction , also what neck diameter.
I would like to at least skim turn the necks .

Or maybe there is a freebore length that would allow me to use bergers or sierra bullets.

This build is for an f-open gun.

 

[Erik Cortina]

.200" freebore, .313" neck.

 

[DennisH]

It looks like 180's are the bullet of choice for the 284?

 

[Julien]

Eric What about the throat diameter .2845 or maybe .2847 I know in the past I have found that a tighter throat worked well for me but I think to tight might cause more pressure .

 

[Erik Cortina]

I don't remember, but Kiff will point you in the right direction.

 

[boogershooter]

If you neck up a peice of unturned Lapua 6.5-284 brass(blue box) and load a bullet, what does it measure? I am guessing .319 ???? Thank you and Happy Thanksgiving.

 

[Erik Cortina]

If you neck up a peice of unturned Lapua 6.5-284 brass(blue box) and load a bullet, what does it measure? I am guessing .319 ???? Thank you and Happy Thanksgiving.

No way it measures .319", it should measure around .311" - .312" loaded round.

 

[boogershooter]

Thank you Erik! Should measure, or does measure?

 

[Erik Cortina]

I loaded a 180 VLD into a blue box piece of brass, it measures .312"

 

[boogershooter]

Thank You again Erik! Happy Turkey Day.

 

[Erik Cortina]

Same to you!

 

[Julien]

Thanks Eric for going through the bother of measuring one much apreciated,I would have measured one myself but I haven't gotten my brass that I ordered yet.

When I talk to Dave I will ask him about the freebore diameter but I would like to hear about some of you guys shooting 284's and hear about what you are shooting.

 

[PFAK]

Just be sure you specify Lapua brass when you order the reamer, as they make specific reamers for Winchester brass and Lapua brass. Found that out the hard way. Paul.

 

[Julien]

Just be sure you specify Lapua brass when you order the reamer, as they make specific reamers for Winchester brass and Lapua brass. Found that out the hard way. Paul.

Paul I was aware of the difference the only thing I am not sure of is what freebore[throat] diameter to use I was thinking of going with .2847 but I dont want to go to much.

 

[Lbart]

Julien,
FWIW my 7 Shehane barrels have a 0.2844" lead diameter and my 7/270 WSM barrels have a 0.2843". I am not sure why the WSM is smaller, but that is what the prints show. It was not intentional. They seem to work A-OK. Length is 0.200" on each.

Good luck with the build.

Larry Bartholome

 

[bartman007]

I've measured a few necked up 6.5-284 Lapua blue box cases too, and I have found they are consistent at .313 so Erik's measurements confirm across the ocean that Lapua and Berger provide consistent product. That is with Berger VLD's seated.

In regard to reamer neck dimension, I gather a .315 neck will allow me to skim 1 thou off the cases, to take them to .312 which will run a 3 thou clearance to the loaded round.

Is 3 thou a good clearance to run? Or is there an optimum clearance?

 

[Erik Cortina]

Is 3 thou a good clearance to run? Or is there an optimum clearance?

I like .004" clearance.

 

[Mark Walker in TX]

I'm running .003 and it's working well. There is no "optimum"...

 

[bartman007]

Thanks guys. Looks like .0035" will have to be it

No, really I have played with it a bit, and have found I get more carbon on the outside of the neck if it gets too sloppy. On the other hand, I have a 6mm BRX that gets a bit tight after 80+ rounds without cleaning (0.002" clearance).

So it is a balance.

 

[Julien]

Well I spoke to Dave Kiff yesterday I ended up getting a .313 neck ,.203 freebore and .2845 freebore diameter , according to Dave this is what he has been making for blue box lapua and 180 bergers.

What do you guys think of benchmark barrels I have a chance to try one out .