Barrel vs chamber?

[lil' bear]

Just a thought I was having. Does the chamber of the barrel really matter or are you at the mercy of the barrel?
For example if you were to take a 6.5mm barrel, use the same bullet and same powder. Starting at the smallest case and slightly increasing the chamber to the next case.

Chamber it in 6.5prc and find your accuracy node. Then re-chamber the same barrel in 6.5saum, find your accuracy node. Then re-chamber in 6.5ss find your node. Re- chamber in 6.5 western. Ect....

Would you actually see any difference in your nodes? Or would the barrel tune out to roughly the same velocity?

 

[Axlrod]

Usually most cases like to be close to full of powder for best results.
On a side note I have a bunch of different caliber Berger's (.243,.257,.264,.284 & .308) that all shoot really well in the 3040-3090 fps range. It's really hard to say without doing it- so when you're done post up the results!

 

[doc holiday13]

Call krieger and Bartlett. Might be a bench rest shooter or two who's done it for sure.

 

[Wrench]

I've done it but only a few times and wouldn't consider my results as the only outcome. I have a 6br that's getting cut and punched to xc now. It's beyond br quality but should be totally adequate for a .75moa gun for another 1k rounds.

Chamber dimensions and location matter a lot. Throw the chamber in off CL and it's not going to make the barrel shine.

Chamber choices can matter. While any cartridge CAN be accurate there are some that are nearly always accurate. If a 6br doesn’t shoot....something is wrong.

Barrels matter.

 

[TaperPin]

Just a thought I was having. Does the chamber of the barrel really matter or are you at the mercy of the barrel?
For example if you were to take a 6.5mm barrel, use the same bullet and same powder. Starting at the smallest case and slightly increasing the chamber to the next case.

Chamber it in 6.5prc and find your accuracy node. Then re-chamber the same barrel in 6.5saum, find your accuracy node. Then re-chamber in 6.5ss find your node. Re- chamber in 6.5 western. Ect....

Would you actually see any difference in your nodes? Or would the barrel tune out to roughly the same velocity?

That’s a great question - are the nodes based on velocity in the barrel. I can’t recall anyone doing it, although I’m sure a number of guys have out of curiosity. My gut feeling is no, based on what does effect accuracy nodes other than velocity. Seating depth can change nodes, as can simple barrel wear, all at the same velocity.

There’s no dispute the shape of a cartridge has an effect on accuracy potential, but it is very small and mainly shows up in the crowd shooting sub 1/8 MOA, which has been put to rest with the success of the 6PPC over other 6mm cartridges based on 223 or shortened 308 head sizes. In 30 cal a 30BR is slightly more accurate than a 308, but it’s only noticeable when shot side by side and the difference is less than 1/8 MOA.

Much of the accuracy of different cartridges has to do with chamber slop from designed in tolerances and clearances. Many older cartridges have large sloppy chambers by design since accuracy wasn’t highest on the list. Have a custom reamer made and almost all the advantages of one cartridge over the other goes away. A 300 Savage would then shoot as accurately as a 308. A 250 savage would be right there with a 25 creed. The current 22-250 chamber specs aren’t bad as is and would be as accurate as a 22 creed.