A few guys have asked about the throats in their 9.3X62 and 9.3X57 rifles. Some throats are quite deep, while others are quite shallow, and this can be a source of no small amount of misunderstanding when comparing, and sharing, load data.
IIRC, it was BUM, a very experienced reloader, who posted a few years ago that he could not seat X bullets out far enough to contact the rifling in his Husqvarna at all. Round Nose bullets were part of the answer to his situation.
Others have discovered that bullets of less pointed profiles could not be seated out to take full advantage of the magazine length.
This 285 gr 0 ogive bullet must be seated very deep in my custom pre-64 chambered in 9.3X62 (top in picture), but chambers just fine seated way out in one of my Husqvarnas (bottom). It should do great in BUMs rifle.
This photo illustrates a fairly deep freebore in another 9.3X62. It was shown clearly by partially seating a bullet, upside down, and allowing the bolt to finish seating as it came into contact with the beginning of the rifling in the chamber. There is almost 1 1/4 caliber of throat before the rifling begins. The long-throated Husqvarna from the picture above has more than two calibers of freebore!
The point is, that all chambers are not the same. They vary, and sometimes greatly, and hence velocities achieved safely do as well. Longer throats, or freebore, effectively increase the chamber capacity of a rifle barrel during firing, with consequently lower pressure using the same load.
Some of the Weatherby cartridges have throats that are more than two calibers in length, and use that advantage to achieve very high velocities. As well, rifles throats wear with use, and a rifle that has several thousand rounds down the tube can be getting far more velocity than when it was new. River Rat has a 358 Norma Mag that he got in 1973. When we first started loading for it, it would barely reach 2800 fps with 250 Speers. Today, it has over 2000 rounds down the tube, and he routinely loads it to over 2900 with good case life and tight primer pockets.
Note: Loads that would be perfectly safe in the deep throat of one rifle, will generate more pressure in another rifle with a very short throat. This is true of all cartridges, not just the 9.3 family.
Post away with your learning experiences, good and bad. Perhaps we can save someone a bit of grief, or at least save them some time.
Ted
IIRC, it was BUM, a very experienced reloader, who posted a few years ago that he could not seat X bullets out far enough to contact the rifling in his Husqvarna at all. Round Nose bullets were part of the answer to his situation.
Others have discovered that bullets of less pointed profiles could not be seated out to take full advantage of the magazine length.
This 285 gr 0 ogive bullet must be seated very deep in my custom pre-64 chambered in 9.3X62 (top in picture), but chambers just fine seated way out in one of my Husqvarnas (bottom). It should do great in BUMs rifle.
This photo illustrates a fairly deep freebore in another 9.3X62. It was shown clearly by partially seating a bullet, upside down, and allowing the bolt to finish seating as it came into contact with the beginning of the rifling in the chamber. There is almost 1 1/4 caliber of throat before the rifling begins. The long-throated Husqvarna from the picture above has more than two calibers of freebore!
The point is, that all chambers are not the same. They vary, and sometimes greatly, and hence velocities achieved safely do as well. Longer throats, or freebore, effectively increase the chamber capacity of a rifle barrel during firing, with consequently lower pressure using the same load.
Some of the Weatherby cartridges have throats that are more than two calibers in length, and use that advantage to achieve very high velocities. As well, rifles throats wear with use, and a rifle that has several thousand rounds down the tube can be getting far more velocity than when it was new. River Rat has a 358 Norma Mag that he got in 1973. When we first started loading for it, it would barely reach 2800 fps with 250 Speers. Today, it has over 2000 rounds down the tube, and he routinely loads it to over 2900 with good case life and tight primer pockets.
Note: Loads that would be perfectly safe in the deep throat of one rifle, will generate more pressure in another rifle with a very short throat. This is true of all cartridges, not just the 9.3 family.
Post away with your learning experiences, good and bad. Perhaps we can save someone a bit of grief, or at least save them some time.
Ted
Last edited:
in .366 Wagner
