A buffalo at close range is a large target. It is sufficient to put half-a-dozen fairly rapid shots into a six group at around eighty paces with your chosen rifle / sight / calibre combination from the shooting positions most commonly encountered in the bush.

Правильно ли я понимаю, что "a six group" означает группу из шести буйволов, на которую вполне можно потратить шесть выстрелов?

Аскер, еще контекст есть?

In my opinion, the correct calibre for buffalo is the largest that can be carried comfortably, handled with absolute confidence, and shot with a reasonable degree of accuracy. With all of the buffalo species, correct first-shot placement is absolutely vital. The buffalo's formidable reputation of being nasty, vindictive, and seemingly impervious to bullets when wounded, stems from either poor initial shot placement or inadequate terminal bullet performance. No animal, buffalo included, will remain on its feet for more than a minute or two with its lungs punctured and the top of its heart or the major thoracic blood vessels that emanate from that area destroyed. Severing the first half of its spinal column will produce the same results. If a good bullet of adequate calibre is shot in the right place and penetrates to the intended target, these results are inevitable. The larger the calibre and the bigger the hole, the more extensive the damage and the more rapid the onset of the inevitable will be-it's as simple as that. The only limiting factor is being able to carry, handle, and accurately shoot the chosen rifle/calibre combination.

A buffalo at close range is a large target. It is sufficient to put half-a-dozen fairly rapid shots into a six group at around eighty paces with your chosen rifle / sigh t / calibre comb ina tion from the shooting positions most commonly encountered in the bush. It is imperative that the would-be buffalo hunter learn to handle and shoot his chosen rifle / calibre combination well before embarking on a hunt. I see no point in anyone being punished by shooting a large-calibre rifle repeatedly off the bench. Once the chosen combination has been sighted in-dead on at 100 paces will be fine-leave the shooting bench alone and practice from the positions you will encounter here in Africa: sitting on the ground with your elbows resting on your knees, kneeling with an elbow on a knee, from a set of shooting sticks, leaning against a convenient tree, or offhand. Repeated benchrest shooting with any large, heavy, recoiling calibre is extremely unpleasant, and all it encourages is flinching and gun-shyness.

The two previously mentioned 9.3mms-the 9.3x62mm and the 9.3x74R-and the .375 Flanged (or rimmed) Magnum are about as low as one can sensibly and legally go. However, it has been my experience that the recoil generated by any one of these cartridges in an 8-to 9-pound rifle is about as much as anyone unaccustomed to firing large-calibre rifles can handle. All PHs, myself included, would rather have a client shoot a buffalo with one of the smaller but legal calibres in the right place than use a monster magnum and place the first shot poorly.

в сабжевом предложении он говорит не о тактике на охоте,
а о точности/кучности стрельбы как таковой - о способностях охотника в общем, тобишь

It is sufficient to put half-a-dozen fairly rapid shots into a six group at around eighty paces with your chosen rifle / sigh t / calibre comb ina tion from the shooting positions most commonly encountered in the bush.
~
показателем достаточности качества стрельбы будет способность охотника положить 6 пуль кучно при достаточно быстрой стрельбе выбранным им оружием из любой позиции, характерной для срельбы из убежища типа "куст" =))

Надеюсь, поможет.