Rebated rim cartridges for precision

[med358-boise]

deleted

 

[fseaman]

Sometime next year I will know empirically how a rebated rim works on an old Weatherby Mk V six lug action. A Pac-Nor 7mm barrel will be here early next year. The ADG 7 Nosler brass will be turned down to fit the .470 bolt face.

Are you willing to share your cartridge design? For parent case, I am not familiar with something called "7 Nosler". Do you mean 28 Nosler?

(repeating know information for reference) Since Weatherby now makes the 6.5 and .338 Weatherby RPM where RPM stands for Rebated Precision Magnum. Function with rebated cartridges is known to work. If your design is based on a 375 Ruger or 404 Jeffery, it may get harder.

so

If your design is similar to any of the rebated rim chamberings in the 6 lug you'll be good. Worst case, get mag box for the next closest chambering and have the bolt stop groove lengthened. I think I have a belted magnum in my 6 lug inventory (not sure, it's late, safe is locked ) If there is a belted magnum chambering for the 6 lug that the OD of the belt is close to your base OD and the COAL is similare, the mag box for that cartridge may bey your friend.

 

[med358-boise]

These folks don't seem to have a problem with it. This list is from 2020 and the2018 list was basically the same.

Cartridge Selection in F-Open Division

In addition, Matt produced an interesting listing of cartridge/caliber types for the F-Open division. This is helpful because cartridge choice is unrestricted in the F-Open class. By contrast, the F-TR division is limited to .223 Remington (5.56×45) or .308 Winchester (7.62×51). You can see that the .284 Winchester (and variants) currently dominate F-Open.

 

[fseaman]

Yes, due to the internal diameter above the web, more psi is exerted over the primer pocket and the sides of the web diameter is reduced for the extractor groove, this allows more brass movement outward either side of the pocket.
Unless the web is beefed up, read this as thicker, and the walls of the case are radiused from the web, then it will expand more laterally.
This is why primer pockets loosen in Norma brass prematurely.

Cheers.

Thank you sir!

I'm gonna restate with reference to my "favorite" rebated rim parent case, the 404 Jeffery and it's offspring. Please tell me if my restating follows your description and the logic there in.

With it's deeper/thicker web and more gradual internal radius the more recent chamberings based on the 404 parent may not experience the "weak primer pocket" endemic to the original 284 Winchester.

So

Painting all rebated rim chamberings with the sins of the original 284 Winchester may be "over exaggerating" and applying faults to a completely different parent design.

Correct?

 

[fseaman]

Cartridge Selection in F-Open Division

It may be just that event but do you know of anyone using the 7mm WSM?

The shoulder is pushed 0.037 and the neck is only 0.243. It seems the original spec was for a 9 twist so a build would need to be 7-8 twist for the heavies it can throw and throating to match.