6mmBR-DX freebore

[AckleyImproved]

Hi

I need to order a reamer, but before I do I need to know what sort of freebore I want to run. Plan on using 105/107's.

My last Dasher I went for 0.125"FB, which I really liked. I wouldnt mind something similiar to that bullet position in the case on the 6mmBR-DX.

I have had Custom FL bushing die for the 6mmBR-DX sitting here for a few years doing nothing, so time I did something with it!

Cheers

 

[cmillard]

just tell dave kiff what bullet you are using, and where you want the bullet in relation to the neck shoulder junction.

 

[tclaunch]

If my memory serves me, the BR-DX neck is .039" short of 6BR length, the Dasher .100". This leaves the BR-DX with a .061" longer neck. To keep the same position in relation to the neck/shoulder junction you should use the same amount less freebore. .125" less .061" for a .064" freebore. I like a bit more than .125" on my Dasher and would opt for .090" freebore on a BR-DX if it were my project. There are other figures come into play. The chamber length the most. This is figured on the BR-DX the same chamber length as your Dasher. I like 1.565" minimum to 1.570"

 

[fm1947]

Could someone exsplain freebore, I think I understand but could not exsplain it my self, useing a 6mm br as the topic and a out of box gun like savage versus a custom chamber with less or no free bore , I would like a visual description if possible to understand totally.

I believe it is amount of throat less throat length means less bullet length to lands. correct me if i am wrong

 

[AckleyImproved]

Well, I think I have worked out this. If I run 0.125"FB on the 6mmBR-DX, that will leave around .243" of projectile in the neck, but since having a longer neck would result in the projectile being well above the neck shoulder junction.

Thinking it could be a little longer actually!! Sound like a plan?

As for freebore, take a given projectile, longer freebore will seat the projectile out further in the case before jamming in lands, shorter freebore seat deeper hence shorter OAL.

 

[fm1947]

Yep, got it

 

[NorCalMikie]

If it was me building a rig, I'd make sure I had as much bullet in the case neck as I could get for starters. Once the chamber is cut, the freebore can't get any shorter!! And as you fire more rounds, the freebore will get longer and the bullets (105s/107s) you started out with won't be in the same position in the case neck. Think "less freebore" when you start. JMHO, Mike.

 

[AckleyImproved]

If it was me building a rig, I'd make sure I had as much bullet in the case neck as I could get for starters. Once the chamber is cut, the freebore can't get any shorter!! And as you fire more rounds, the freebore will get longer and the bullets (105s/107s) you started out with won't be in the same position in the case neck. Think "less freebore" when you start. JMHO, Mike.

Yeah.. good idea, but I am liking the idea of a freebore of 0.125". As said it will leave around 0.243" of projectile in the case, and from what I gather that is a good amount... that is, keep a full caliber width in seating depth. Is this like a rule of thumb to use?

Cheers