I am wondering what the minimum barrel wall thickness should be in the chamber/thread extension area of the barrel. Im sure it depends on caliber size and pressures, so I guess we will use 25-06 and .350 Whelen.

Thanks

I dont specifically know how thin one can really go in chamber wall thickness.
I know that 7/8"dia.[.875"] barrel thread retains enough chamber wall thickness/strength for modern high pressure 308win, 30/06 based cartridges, but I dont know the minor dia. of that thread.
7/8-9 2A has minor dia. of .7368
7/8-14 2A has minor dia. of .7858
I dont know if they are the same 7/8 threads as used on gun barrels.

The FA Model 83 454 operates up to about 57,000CUP, am curiuous to know the outer wall thickness of the chamber.

FWIW:

Urban legend has it that Ackley claimed that AT LEAST 0.125" was necessary. IMO that's pushing things, A LOT! But, read on....

My own experience, personal experience, has been that Martini Cadets @ 0.750"-14tpi are fine with .223 Rem/5.56 chamberings (0.375") @ 50+K and also 219 Zippers & Improved Zippers (0.422") @ 40-45K but not the 225 Win (same 0.422") @ 50+K. They also work quite well with the 44 Mag (0.457") loaded to 40K.

Again, FWIW, as always YMMV.
Regards, Joe

I am mainly concerned about the thread extension area. Since the action is surrounding the thread extension does that not add strength?

quote:

Originally posted by Aaron Little:
I am mainly concerned about the thread extension area. Since the action is surrounding the thread extension does that not add strength?

Very, very little. Consider that the outer ring doesn't apply any force directly inward at a right-angle to the barrel's bore, its force is primarily directed at a right-angle to the thread surface. In the case of square threads the force is directed almost 100% forward. In the case of vee threads the inward force, although present to a greater degree than with square threads, is greatly reduced by the 30/60 degree slip angle of the threads. This same 30/60 slip angle, when the barrel tenon is momentarily jolted and expanded by the rifle's discharge, tends to slide the barrel and receiver thread surfaces further into engagement rather than resisting more firmly as would be the case if the outer ring was a tight shrink fit.

IOW no matter HOW tight you cinch it, IMO the outer receiver ring will not add much if any measurable hoop strength to the barrel's thread tenon. And besides, there's almost always an open unthreaded and unsupported section behind the receiver/barrel shoulder anyway.
Regards, Joe

I'm no firearm engineer, but I think JDS is correct. Our tooling at work is designed to be put together in "hoop" stress. These are smooth O.D.'s pressed into smooth I.D.'s. Very smooth. The amount of press fit we need to have the correct amount is way too much for thread assembly. ( I think our press is 200ton)
I see it as the barrel takes care of the cartridge radially while the receiver contains the bolt. JMHO.

quote:

Originally posted by walnut:
I'm no firearm engineer, but I think JDS is correct. Our tooling at work is designed to be put together in "hoop" stress. These are smooth O.D.'s pressed into smooth I.D.'s. Very smooth. The amount of press fit we need to have the correct amount is way too much for thread assembly. ( I think our press is 200ton)
I see it as the barrel takes care of the cartridge radially while the receiver contains the bolt. JMHO.

You got It!......Tom