Building my first 6BR

[jelrod1]

Hey guys. I'm going to start building my first 6br soon. I have a Rem 700 SPS in .308 as a donor for the project. I'm looking to just keep the action from it and get it trued. I want to use a KMW Sentinel stock as I have a Sentinel rifle in .308 and really like it. I'm leaning toward a Krieger barrel. What twist and length do you guys recommend? Also, any other suggestions would be welcomed along with a preferred gunsmith for the project. Thanks for the help.

ETA: the guns use will be primarily for target shooting out to 400 yards with most 200 or less. Another question would be what bullet would you recommend for that as I am new to this caliber.

I want to use Lapua brass and not turn if possible.

 

[jonbearman]

Make sure when you order your reamer tell ptg or whomever that you need the reamer for the new blue box brass.The reamer should have a .2704 neck.68 grainers work real good to 200-300 and it seems most guys are now shooting the 105-115 dtacs for long range work.Get a 1 in8 turn barrel and you can shoot anything you want from light to heavy.I would look at the home page under gunsmiths.

 

[Tim Singleton]

I have 2-6brs one is a 12 twist short 22" barrel set up for short to mid range with 80 gr bergers at 3150 fps. the other an 8 twist set up for 600 yds shooting 105 gr bergers at 2900 fps

You will be in love with your new 6BR. Your post says target shooting out to 400 yds. I would build a 10 twist throated for Berger 90gr at over 3000fps.

An 8 twist will let you shoot everything but maybe throated to long for the lighter bullets , if you throat it shorter then the heavy bullets are to deep in the case. That is why I ended up with 2-6brs one for shooting up 80grs and another for the heavies.
You just need to decide what bullet you want to shoot then pick a twist

 

[captainzeke]

I have a 6 dasher in a Kmw sentinel stock 8 twist Krieger ! I'm still on the fence about the stock and its ergos and its use in bench rest or f class ! But I would do it love the cartridge !

 

[GSPV]

I have two 10 twist straight 6 BRs that I use in 300 yard matches and for hunting. I use the Berger 87 gr VLD Hunting. I push it with 30.5 gr of 8208 XBR. I do want to try the 90 gr Berger BT to see if it is easier to tune than the VLD.

In your place, I might go to the 8 twist for the flexibility. The additional problem that you fight, though, is freebore. The stubby bullets that do well at 100-200 want less freebore than the long, point bullets that do well at long range. That's why I went with the 10 twist and midweight bullets for my application.

No matter what, I would look at a max heavy varmint contour at 27 or 28 inches. At that, depending on the stock and scope, you might have to add weight in the back to keep it from being nose heavy and dorking up tracking. Though that particular stock looks awfully heavy in the butt anyway.

Here is one of the 6 BRs. It is Mike Ezell's fine work. He is "GunsandGunsmithing" on here.

 

[Shynloco]

JelRod1,
Just a tip in case you are unaware...I ordered a new Kreiger barrel (1:8 ) for my Savage Benchrest 6mm from Kreiger in mid March. I was very specific both when ordering the reamer from PTG (which I just received) and the barrel from Kreiger. The estimated time of delivery on the barrel is Jan 2014. Info only.

As for the bullet/distance I shoot, I shoot strictly 100yds and am using Bart's 68 gr Ultra FB bullets being pushed by VVN133.

Alex

 

[jelrod1]

Thanks guys. I think the 10 twist mid weight bullet combo sounds like a good route to take for my purposes. Krieger lists some MTU 9 and 10 twist in stock, but I know nothing about those. My .308 has a Light Varmint contour in the Sentinel stock. Not sure what else works in there. I can call Terry Cross on that.

I have never ordered a reamer from PTG for my own rifle before. If I tell them what brass bullet combo do they know how to spec out or do I have to tell them?

Captainzeke and I have similar tastes. Here is my .308

 

[GSPV]

The MTU is a target profile. It's 1.250" at the shank for 2.75" then tapering from there. It is closely akin to the Heavy Varmint profile.

The main difference between it and the Max Heavy Varmint that I wrote about is the the MHV's shank is 6", giving you the option of getting more weight toward the rear.

See http://www.rifle-barrels.net/barrel.html for some info.

But time is always a factor. I always keep ahead on barrels. They are consumables, not capital assets.

On your reamer, if you call PT&G and ask to speak to Dave Kiff, tell him what bullet you want to shoot and he'll either pick one from current designs or custom grind it for you.

While you're at it, talk to him about what dies to use. My chambers are cut with a PT&G reamer and the Redding Type S FL bushing die works well.

 

[lpreddick]

agree with all said but...the freebore issue is real. for short range target shooting i am absolutely delighted with my 14 twist as it will one hole 68 and 70 gr bullets repeatedly! for heavies, the freebore will be longer and could cause a problem as to how much bullet you have in the neck and still be able to seat into the lands...most 6 mm brs seem to like this. a fast twist will indeed stabilize the lighter bullets but perform best with heavy ones and i have suspected this with other calibers. my 22 br 8 twist shoots everything but one holes with 77 gr smks only. another thing about long freebore is that after shooting a lot it will move out and to seat the same into the lands, you'll have to seat the bullet out further. with the brs long neck a short freebore with light bullets allow you to move the bullet out many times and still have sufficient neck holding the bullet. the above rifle was chambered with a reamer having long freebore but i have enough neck to work for now. when the lands move too much i'll consider rechambering with a new reamer as mentioned and order it with shorter freebore. one other thing about slower twist and lighter bullets...they cost less, sometime half. you will enjoy the 6mm br!

 

[jelrod1]

Thanks again. The knowledge here is immense. So, if I wanted to shoot 70 grain smk I would use a 14 twist and if using the berger 90 grain target (non VLD) use the 10? Then order the reamer for the chosen bullet to use Lapua brass (no turn) and have the free bore set specifically for that combo. Could there be somewhat if a middle ground there with twist and free bore to allow both bullets or is it not worth risking? Honestly the thing will be strictly for target and I have no range that let's me stretch out further so the lighter combo may be good. Lots to think about.

 

[GSPV]

Just making sure on something...that, other things equal, the longer a bullet is, the faster the twist required to stabilize it.

It is impossible to craft a solution that is ideal in all circumstances. A fast twist is great for the long bullets for long range/wind, but it is going to recoil more and torque more in the bags than a slow twist for the stubby bullets. OTOH, at 300 and 400 yards, the short stubbies are going to give you fits in the wind.

So, like anything else, you have to look hard and realistically at what you are going to do and design to those requirements.

If you want to preserve 300-400 yard shooting, I'd suggest a 10 twist and mid weight pills.

I'd also build it heavy...weight can gloss over gun handling mistakes.

Anybody here will be happy to help.

 

[jelrod1]

Thanks for the suggestions. I got things underway today with this project. I ordered another KMW Sentinel stock to match the likeness of my .308. I also took your advice and talked to Dave Kiff at PT&G and ordered a reamer and gauging ground for Lapua blue box no turn and free bore set for 90 gr Berger match target BT. I think FB was .089. Lots of brass and bullets are on the way from Powder Valley. I'm hoping varget is ok for this since I have tons of it.

I still need to order the barrel. Probably going with a Krieger 10 twist in either MTU or Heavy palma contour. The MTU is in stock but I'm thinking of waiting on a HP.

Anything else I'm missing? I'll have to send my 700 action to the smith doing the work and get it trued and bushing put in for the smaller firing pin. Anything else you would recommend?

 

[GSPV]

Varget will do you great.

In my 10 twist straight 6BR, using Lapua brass and Wolf/Tula primers, I shoot 30.7 grains of Varget with the Berger 90 BT.

When you get your brass, inspect the flash holes. I've seen a few that have a significant flake of brass showing.

I also suggest that you run a 6mm mandrel through and size back down with your neck bushing. The factory necks on mine were really tight.

Remember: The worst measurement is superior to the best assumption.

 

[jelrod1]

Thanks again. I have a 28" Krieger 10 twist on the way MTU contour. Any suggestions on what length to finish for the combo I'm using? I'm thinking of leaving it as long as I can.

I also have a Whidden FL bushing sizer, Wilson inline seater, K&M 6mm mandrel, and a Lee 6ppc collet die coming. I use pretty much the same things for .308 and want to try the collet die with this one. May or may not need it, but wanted the bases covered.

How do the 90 grain Bergers shoot for you? What other short to mid range options do I have with an .089 free bore if these are not satisfactory?

 

[Tim Singleton]

Dont over look the 88 gr Berger flat base bullet

 

[GSPV]

My other go-to bullet is the Berger 87 VLD Hunting. It's a tad more difficult to get the seating depth exactly right.

You might also try:

1. Lapua 90 gr Scenar.
2. Hornady 87 gr and 75 gr Vmax
3. BIB 95 gr flatbase. - .104 freebore is best, IIRC. I have 80 something FB and still get away with it.
4. Any of the Berger 60-something grain bullets.
5. Nosler 90 Ballistic Tip
6. Speer 70 gr or 75 gr

I don't know if I'm supposed to let the cat out of the bag yet, but my distant cousin, Larry Moore of Hillbilly Bullets is making a nice midweight custom 6mm bullet.