Critique my 6 dasher reamer specs

[bsumoba]

I wanted to get some input on my reamer specs. I dont have a pic of it now, but here are the major specs.

I will be using 6mmBR Lapua Blu Box brass and 105gr hybrids. I will probably do a no neck turn or cleanup on the brass. Barrel will be a 1:7.5 twist, 0.237 bore.

Is this too much neck clearance for Blue box lapua? If I cleanup the brass to 0.012", I will have somewhere around 0.006" clearance. If I leave necks as is, I will probably get around 0.005"

Base/Web Diameter: 0.4707"
Shoulder Datum Diameter: 0.3500"
Shoulder to Neck Junction Length: 1.3087"
Max Brass length: 1.5700"
Neck Diameter: 0.273"
Freebore Length: 0.1550"

 

[kemiha]

I'm no expert, but I believe the recommended freebore for 105 grain Berger Hybrids is .135", someone who knows better may be able to chime in.

I would go with the .2705 neck size for a no-turn neck.
--
Kevin

 

[ridgeway]

I'm no expert, but I believe the recommended freebore for 105 grain Berger Hybrids is .135", someone who knows better may be able to chime in.

I would go with the .2705 neck size for a no-turn neck.
--
Kevin

That number is by all means is not set in stone. Lots of guys have very good success way over .135".

 

[Alex Wheeler]

Freebore is the hardest number to hit on a reamer. A true .135 would work ok, but .140-.150 is where I like with a 1.555" case. .135 may be the way to go with a 1.570 case. Depending on who makes the reamer I would run it into a barrel stub and check the seating depth that way. I have seen them way off.

 

[ShootDots]

Brian, my reamer is exactly like yours, except my neck is a .271 instead of a .273.. You will do very well with that reamer..

 

[bsumoba]

So based on this info and with more research that I did, I will be changing my neck to 0.271 and a 1.555" case length.

thanks everyone.

 

[pmarauder]

I would go .4715 on your base... Seems like most factory FL bushing dies dont quite size the base enough. By about the 5th firing....you may get clickers, and usually is due to not enough sizing at the base.. My reamer is .4712 at the base, and I wish I had a tad more.

Derek

 

[bsumoba]

Here is the final print. Made a few slight modifications:

Kudos for JGS. They are very responsive and have accomodated all my changes despite me changing it every couple days. I think this one is final.

 

[ridgeway]

I just noticed you have a freebore diameter of .2435". I would go tiny bit more to a .2438" for the simple fact that some lots of Hybrids seem to have a large shank diameter. If you have normal shank diameter under .2435", the .2438" won't hurt anything.

 

[pburr]

Glad I saw this then I compared it against the print I have with JGS and the freebore diameter of mine is even smaller at .2433. I also noticed that my bore size is set at .236 and the barrels I have are .237. Would the barrel size of .237 also have an impact on the freebore diameter? I also plan on using the 105 Hybrids.

 

[pburr]

Here is the print I have on order now.