6 BR freebore

[Devildog99]

Looking for a little help. When cutting a chamber for the 6 BR, what length of freebore is best for bullets in the 68-70 gr. range? Thanks.

 

[fdshuster]

Keep it short--- real short. I made the mistake of chambering one of my 6BR's with .104" of freebore and now at 775 rounds fired I'm running out of case neck when seating to touch. Estimating that around 12 to 1400 rounds I'll not be able to use my favorite bullet anymore, the 95 gr. Berger VLD. If you really want to nail to down, load a dummy round with your #1 bullet of choice, seated to the depth you want it (base of the bullet at, or very near the neck/shoulder junction?), and send the dummy round to your reamer maker specifying that the seated bullet touch the lead/ lands. A good time to also specify what chamber neck dia. you want, like a .272" no-turn? And I also specify chamber o.a.l. at 1.570" for my Lapua brass 6BR's. Do this and you get exactly what you want, not whatever the reamer that someone may have had in their shop will produce. New reamer with a floating pilot sells for $138, and if you don't want it after the chamber is cut you can always sell it & get a good portion of your cost back. if it turns out to be a good chambering, keep the reamer for future use.

 

[JohnnyJohnson]

If you are only going to shoot the bullet weights you've listed there is no way you need a throat longer than 40 thousands.

 

[JohnHenry]

Just had one built. Zero freebore and 1 in 14" twist for the 68 grain bullets.

 

[deadlyswift]

I AGREE! I just got my reamer from PT&G for a 6br. I seated my bullet at approximately, .050 above the shoulder/neck junction. I sent a note that I wanted the bullet to touch the lands at the seated depth. The reamer came to me with a .021 free bore. This was my frist reamer that I had ordered. I was sure that .050 off the shoulder/neck junction was a good place to be with the 95gr berger vld. This allowing me to jam the berger as they seem to like to be, as well have enough room to jump them if that be what they wanted, and still stay away from the dreaded doughnut that occurs with firing and sizing brass. Also have plenty of neck to have at least the .243 cal. length seated into the neck. When I got my reamer and figured out that .021 was my free bore, I was worried that I done something wrong when seating my bullet! Most had stated that their free bore was .100 to .104 for the 95gr. berger vld. So I contacted a friend about the free bore. He wanted to buy my reamer! I had not thought about throat erosion when seating my bullet! In short if it was me I would seat my desired bullet at approxmately .050 above the shoulder/neck jucntion and request that it touch the lands at it's depth! I think you will get better barrel life and accuracy with the the bullet seated at .050 off the shoulder/neck junction! Not many rifles, and I have only experience with factory barrels so far, but all factory barrels that I have have shot awesome with a .020 jump to a .010 jam. So you have plenty of neck to play with here either way! Custom or Factory!

 

[fdshuster]

Devildog99: As you can see, we are all pretty much in agreement. Bottom line is, don't give up all that valuable throat length to the throat cutting length of the reamer. Put it to good use by----- wearing it out by shooting = longer barrel life and accuracy potential. I may send my .104" reamer back to Pacific and have the throat shortened to deadlyswift's .021", for when the barrel has to be set-back & re-chambered.

 

[Ackman]

The 6BR has a long neck. With those bullet weights you don't want any freebore. My 6BR reamer has .271"nk, 0 freebore. Just touching the lands a 70BalTip seats to the beginning of the neck/shoulder junction radius. A 65VMax seats about .050" higher, and a 55BT seats 1/2way down the neck. A 55BalTip has the highest BC of that bullet weight and accuracy load is over 3900 in my 14twist barrel. Also, Lapua brass has very uniform length....spec. the reamer .010" longer than case length.

 

[johara1]

Ackman, I can't say the Lapua brass is uniform in length different lots range from 1.550 to 1.563.when i need long ones to make a dasher i seem to end up with a short lot......jim

 

[Ackman]

Ackman, I can't say the Lapua brass is uniform in length different lots range from 1.550 to 1.563.when i need long ones to make a dasher i seem to end up with a short lot......jim

That's why you get all the brass you'll need first and spec. the reamer to it.

My Lapua and Lapua/Dakota has been right at 1.750" with no more than about .001" variation. The 6BR is dead nuts on 1.555".....all the same lot. With .243 I've found about .002" max. variation in caselength.

 

[johara1]

Ackman, Just checked a box in i just made dashers out of a the variation .006 in a 100, the other box of the same lot was even shorter........jim

 

[Ackman]

Well Jim.....you're just an unlucky guy. Too bad.