too much freebore??

[243winxb]

Weatherby rifles have extra free bore . Could the Christensen be chambered this way to load hotter and get more velocity with less pressure?

May shoot very well with extra bullet jump?

I dont see a SAAMI chamber drawing?

Just a guess.

 

[spclark]

... but the Christensen rep told me they use a SAAMI reamer in all their rifles.

Then I’d ask them for a reamer drawing for the chamber they’re cutting in the barrels they supply.

Far as I know, there is no “SAAMI” reamer spec for a 6.5-284 chamber;
here are links to the ANSI/SAAMI website where their official chamber dimensions & ammuntion performance standards can be viewed and downloaded:

http://saami.org/specifications_and_information/publications/download/Z299-4_ANSI-SAAMI_CFR.pdf

There are two different ‘flavors’ of 6.5-284 though, depending on what brass is used (Norma factory vs. 284WIN necked down) alongside what are probably quite a number of minor variations for chamber dimensions. These two major variants have caused problems before for shooters, might be why you’re seeing what you do.

If you’re getting 0.1” bearing surface into your case neck @ land contact, I’d just shoot it. With this chambering you’re not gonna need to chase the lands much anyway! This is a notorious barrel-burning cartridge:

http://www.accurateshooter.com/cartridge-guides/65x284/

(LOTS of relevant info there even if it’s over 12 years old now.)

 

[JRS]

Is it chambered for the NORMA version, or, the Winchester version? The difference is substantial. NORMA has a COL of 3.228". Winchester is usually 2.800"

 

[243winxb]

3.228" COL http://www.accurateshooter.com/cartridge-guides/65x284/ seems long? Do i read it correctly?

Hodgdon has 2.950" as the longest COL. with a 130 gr. Wonder what the case head to ogive measurement is?

JRS & spclark posted while i was typing. Great info i didnt know.

 

[JRS]

3.228" COL http://www.accurateshooter.com/cartridge-guides/65x284/ seems long? Do i read it correctly?

Hodgdon has 2.950" as the longest COL. with a 130 gr.

JRS posted while i was typing. Great info i didnt know.

The 6.5x284 NORMA is CIP approved. The Winchester version is all over the map

 

[spclark]

3.228" COL http://www.accurateshooter.com/cartridge-guides/65x284/ seems long? Do i read it correctly?

S’what I mean about ‘variants’ in my post. That drawing doesn’t specify what bullet profile’s used.

And there are way more 6.5 bullets now one can choose from than in 2005.

In the load chart accompanying that article there’s a wealth of info about what was working back then, much of which still had merit.

‘Course the OP could just ask his rifle-maker for their loading recommendation for the rifle & chamber he bought, see what they use thenselves....

 

[NorCalMikie]

That is a cute saying, "You looking..", Again, the man that built the rifles is a very disciplined reloader.

If that's the case, my guess is THERE IS NO PROBLEM.

 

[243winxb]

https://load-data.nosler.com/load-data/65-284-norma/

Loaded 2.980" COL.

Now all we need to know is it a Norma or Win. ?

Two different die sets made.

 

[JRS]

NORMA says for serious competitors, the throat length for the 6.5x284 NORMA is between 0.175 and 0.212. The most accepted length is 0.212, though some will choose between 0.175 and 0.188

Christensen Arms should be willing to provide the OP with the throat length.

 

[spclark]

Christensen Arms should be willing to provide the OP with the throat length.

Agreed, and if he can get a chamber cast made & measured (or is willing to do it himself, not a difficult task), the freebore will be quite evident.

 

[JRS]

Agreed, and if he can get a chamber cast made & measured (or is willing to do it himself, not a difficult task), the freebore will be quite evident.

Looking at the Bullets dot com website, the PT&G reamer they sell has a throat length of 0.188

I just received an email from Cade, at Christensen. He says they chamber everything to SAAMI specs. CIP and SAAMI work hand in hand, and since SAAMI does not list this cartridge, unless a reamer has been custom ordered, the reamer used is made to CIP dimensions. The NORMA COL is designed for a maximum 3.228" to accommodate the heavier and longer match grade bullets at that time. NORMA realized people would have to chase the lands at some point, thus the 3.228 COL dimension.

 

[spclark]

CIP and SAAMI work hand in hand, and since SAAMI does not list this cartridge, unless a reamer has been custom ordered, the reamer used is made to CIP dimensions. The NORMA COL is designed for a maximum 3.228" to accommodate the heavier and longer match grade bullets at that time.

Right, and CIP'S proof barrel specs for the NORMA 6.5x284 cartridge shows a freebore (dimension s on lower drawing here) of 8.02mm or 0.3157", quite a bit longer than the 0.188" throat from PT&G's reamer.

(Their note regarding dimensions & tolerances for proof barrels can be found here.)

Is there somewhere else CIP makes available 'approved' chamber drawings for firearms in typical use, not just specs for proof barrels?

PT&G shows 6.5x284 Norma (CIP) & another labeled Match finish reamers (but no print's available for either unless you ask for one) then there's a 6.5x284 Winchester along with an option for one with any freebore, neck & OAL desired.

0.100" bearing surface in a case neck's certainly enough to hold a bullet. Folks do with even less in some cartridges & they still shoot well!

 

[918v]

I called them and they acted like it wasn't a big deal. He said the rifle met their sub MOA guarantee or it wouldn't have been shipped out. But he did say that I could send it back for them to look at. It took over three months to get the rifle after I ordered it. Who knows how long it will take to get back.

Freebore length is not a big deal unless you like chasing lands. More important is consistent, correctly timed, bullet base exit out the muzzle.

 

[HeathGT]

Is it chambered for the NORMA version, or, the Winchester version? The difference is substantial. NORMA has a COL of 3.228". Winchester is usually 2.800"

Norma version, my overall length with the 142 accubond lr is 3.269" and the base to ogive is 2.652". I guess when you think about it I'm only .042" longer than the specs. I'm loading some rounds for it now, gonna try it out hoping my worries go away tomorrow! Thanks for everyones input. I do appreciate it.