.338 BR vs .338 Spectre
 

I’m debating between the .338 BR vs .338 Spectre. There doesn’t seem to be Starline 10mm magnum brass available for the Spectre so I’m leaning towards the .338 BR (Whisper) since it uses the more common 7mm BR brass and also the more common .308 bolt face. I can get dies for either so that’s not a problem.

Does anyone know if there is a .308 compatible bolt for a standard AR-15 upper (*not* AR-10)? Or can the 6.8 bolt face be opened up slightly from 0.421 to 0.473?

Any other advantages to one over the other?

The expensive way to get a 308 bolt for an AR-15 is to buy a RRA 458 Socom upper.
They don't sell the bolt by itself. You might try Marty at Teppo Jutsu : TeppoJutsu@peoplepc.com
I'd suggest you check cartidge length for the bullets you'd like to shoot. In my opinion the 338/7mmBR loaded with VLD bullets is closer to 308 length (2.8"), not 223 length 2.26"). Of course you can shoot shorter 338 bulelts, but why go to all the effort for a 338/7mmBR to do that. Just shoot a 300-221 if you go below 240 grain bullets. they'll have better BC's and as much energy.

It's real easy to get a DPMS LR-308 or AR-10 with a 308 boltface and a magazine.
the right size. If I wanted a subsonic AR-15 in 338 I'd shorten and open a 7.62x39. Bolts are readily available. Considering the available of dies and reamers for 338-7mmbr or 338-10mmMag it's about as easy to make a new wildcat.

A 308 dia bolt for the AR15 can be had here for $65.http://www.mgimilitary.com/store/ind...85b8f6d3ddd69d
The spectre is aprox .23 shorter than the BR. That can be fixed by a slightly shorter chamber & reducing the neck length on the BR case. I have a modified 338BR reamer to be here this week. I hope by early march to have all the issues resolved. The AR10 with its 308 mag would be best for the BR case but I dont want or need that much gun. The last time I saw some 338Spectre brls for sale they were in the $400 range. No thanks. If you want a specter contact Marty at Teppo Jutsu. See what he charges. If you would like to look at the BR case, contact me & I can give you some #s on a 338BR brl/upper. I am also looking at using the 44AMP brass. This matches the spectre lenth. Lots of options here.

Does anyone happen to have a .338 BR cartridge drawing they can share? If not what is the COAL and the brass length?

Thanks.

Bolts can be opened up to .514" which is what the 50AE is .I did that for Tromix years.I also made the 50 AE barrels for them.So opening up a bolt is easy.The problem is getting an extractor for it.

I think that case head diameter on 10mm brass is the same as the case head diameter for 6.8spc brass. So you might be able to make 338 Spectre cases by cutting 6.8SPC brass.

Then you could use a 6.8 bolt.
320pf

its the same but you will need to neck ream.

What about the SSK 338#2
 

JD Jones uses the 221 FB and open it up to a 338 caliber, just like his 300 Whisper.

Midway has 10 mm mag brass in stock. I just got 100. I also just got .338 Spectre dies from CH tool and die, they were in stock and I got them in 4 days!

What bolt do you use for a spectre? Do you just have to have one opened up or will a 6.8 spc bolt work?