6ARC Tikka

[The Guide]

I'm confused. How does the bolt face support the case head? I'm not sure why firing a 441 case on a 473 bolt face would be an issue at all.

I'm definitely not talking about firing a 6aec round in a 308 rifle. Only using the 308/473 bolt.

I am under the impression that the bolt face diameter is sized close to the diameter of the case to provide support during firing. As in prevent outward growth of the brass and provide the back stop for the chamber during firing. If that's not the true and the bolt face doesn't have a role in supporting the case head, I'm always open to learning!

I see. No it doesn't support the case in that way. If it did, you would need a special bolt head for many different cartridges. Example, Tikka magnum bolt can shoot 300wm, 300saum, 300wsm. Different rim diameters and body diameters.

I'm confused. Are you saying the bolt face doesn't need to match the cartridge? That you could use a typical short action with a .473 bolt face and rebarrel to say a 223? I'm sure you know that's incorrect but I'm not getting your point.

The bolt face does not support any part of the cartridge, it only provides a rear face for the chamber the same way the rear breach of a single shot rifle does. The issue using a larger bolt face with a smaller cartridge rim is that while it would feed in and fire properly, extraction would be your primary issue. No way to pull the spent brass out without changing the extractor system.

Jay

 

[TheM1DoesMyTalking]

I see. No it doesn't support the case in that way. If it did, you would need a special bolt head for many different cartridges. Example, Tikka magnum bolt can shoot 300wm, 300saum, 300wsm. Different rim diameters and body diameters.

The bolt face does not support any part of the cartridge, it only provides a rear face for the chamber the same way the rear breach of a single shot rifle does. The issue using a larger bolt face with a smaller cartridge rim is that while it would feed in and fire properly, extraction would be your primary issue. No way to pull the spent brass out without changing the extractor system.

Jay

Good clarification! Thanks for setting the record straight, @HighUintas and @The Guide

I did a little reading on it and found this:

Bolt Face Clearance
The bolt face always needs to be larger in diameter than the case rim maximum. You can have a larger bolt face, but it’s important to be aware of extraction claw engagement. The bolt face doesn’t contribute to supporting the case like the chamber wall does. This is because the web and rim of the case are so strong that this part of the case doesn’t need to be squeezed in from it’s circumference. Clearance affects both extraction and ejection. Smaller rounds are not a problem, but you may find it difficult to extract them.

Common Bolt Faces Demystified (Bolt Action Centerfire) – Ultimate Reloader

ultimatereloader.com

 

[HighUintas]

I'm confused. Are you saying the bolt face doesn't need to match the cartridge? That you could use a typical short action with a .473 bolt face and rebarrel to say a 223? I'm sure you know that's incorrect but I'm not getting your point.

For tikkas, the only thing you have to worry about is feeding and extraction. If you put a 223 barrel on a 473 bolt Tikka, it probably wouldn't extract reliably of at all because the extractor is not the appropriate distance from the cartridge rim. As far as feeding, I'm not sure if the extra clearance around the cartridge rim would cause any issues or not.