PLENTY of hunters, me included, have been putting the cart ahead of the horse when we enter a gun shop with a pocketful of money.

By then we've a mindset on the calibre we need. Or at least we should.

The selection criterion includes several factors, foremost being a minimum calibre for the humane dispatch of the feral pest/game on which the sights in our mind's eye are set.

The golden rule about using enough gun shouldn't be too far from the centre of our thoughts.

We can build on that. Retail staff generally have shooting backgrounds and steer the unsure in the right direction.

An important consideration may arise. Wholesalers offer specials that may include a particular brand of gun or rifle-scope packages.

Most dealers do the right thing and mention the fact.

The size of hunting lands or the dimensions of a range have a high priority.

The list then subordinates into matters of ammunition availability and cost, along with reloading components.

Recoil and barrel life are worth a thought.

Last - but in no way least - are matters to do with the average distances over which shots will be fired, the number of cartridges expended per trip, and the inherent accuracy and knockdown of that cartridge ... which brings us back to square one.

It's no surprise really to learn that there are a higher set of harmonics out there.

They begin with cartridge selection, descending through a menu that includes the type of projectile most likely to be used.

A prior knowledge of the twist rate that best stabilises the projectile is a handy piece of information.

Rifle barrels have different twist rates.

The prior selection of a sighting system needed for the type of game or targets is another piece of back-to-front-ness we can undo.

It's at this point that hunters and shooters who've nutted things out beforehand select their delivery vehicle ... the gun to launch whatever projectile we're settled on.

There's a neat parallel with fly-fishing. So many fisher folk purchase a fly rod on the strength of its firepower when hooked up to a lusty fish and bent through to the corks.

It's an errant notion. The key criterion lays with the size of the fly to be cast. Flies range from Black Gnats, which need a magnifying glass to be seen, to things more like half an unplucked chook.

At the risk of some contradiction, where a lot of this aforethought falls down is in the vast differences between range and field shooting.

One happens in a controlled environment, where there's a large measure of anticipation or plenty of time to make sure of the aim.

The unexpected is always on the cards in the field. I'd never pass up a feral cat just because the .270 I happened to have pig shooting was too much gun.