10-Sep-2026
Ammunition is the part of shooting most people learn by copying whoever sold them the gun. That works until the first time you stand in front of a shop wall of cartridges, or read a rifle listing that mentions twist rate and bullet weight, and realise you are not sure what any of it means for the shot you want to take. The ten questions below are the ones UK shooters ask most often about ammunition and ballistics. The answers are deliberately general; there is no substitute for your own rifle’s preference or your own shotgun’s pattern, but they will give you the framework to choose well.
The fundamentals
1. How do I select the right ammunition for my shooting?
Start with what the gun is chambered for; that is stamped on the barrel and is not negotiable. Then match the load to the job. For a rifle, that means a bullet weight and construction suited to the quarry: light, fast, frangible bullets for foxes and small vermin, heavier controlled-expansion bullets for deer, and legal minimums where they apply. For a shotgun it means shot size, load weight, and shot material suited to the target: small shot and light loads for clays, larger shot and heavier loads for game and wildfowl. For an air rifle, it means a pellet shape and weight that your barrel shoots accurately. In every case, accuracy in your gun beats theory on paper.
2. What is critical when selecting ammunition for a firearm?
Three things. The cartridge must be exactly the one the gun is chambered for; .308 Winchester is not .30-06, and 12-bore 70mm is not 76mm. The chamber length and proof of a shotgun must be adequate for the cartridge, which matters for older guns and for magnum loads. And the pressure and construction must suit the barrel: steel shot needs a barrel proofed and choked for it, and solid or monolithic rifle bullets behave differently from jacketed lead. If a listing or a box leaves you unsure on any of those points, ask before you buy.
3. What affects the way a projectile performs when it is fired?
Muzzle velocity, bullet weight and bullet shape, expressed as ballistic coefficient, determine how far and how flat it flies and how much energy it carries. Barrel length and rifling twist influence velocity and stability. Then the environment takes over: wind pushes the bullet sideways, gravity pulls it down, air density changes with temperature and altitude, and range multiplies all of it. A shotgun pattern is shaped by choke, cartridge, shot size, and wad. Understanding these variables is what lets you predict where a shot will land rather than hope.
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Rifles and calibres
4. Which factor has the biggest effect on a rifle’s maximum range?
Muzzle velocity combined with the bullet’s ballistic coefficient sets the maximum range; the angle of the barrel sets whether you reach it. That last point is the one that matters for safety. A rifle bullet fired upward at a rising bird, or a rabbit on a skyline, can travel a very long way, which is why every UK shooter is taught to know their backstop before considering the shot. Weather and altitude change trajectory at the margins, but they do not change the rule.
5. What is a rimfire rifle, and how does it differ from centrefire?
A rimfire cartridge has its priming compound inside the hollow rim of the case, and the firing pin crushes the rim to fire it. It is cheap to make and limited to low pressures, which is why rimfire calibres such as .22 LR, .17 HMR and .22 WMR are small, quiet and ideal for rabbits, rats and target work. A centrefire cartridge has a separate primer in the centre of the base, can be loaded to far higher pressures, and can be reloaded; it covers everything from .223 for foxes to the deer calibres and beyond. Both are Section 1 firearms in the UK.
6. What is .308, and is it the same as 7.62?
.308 Winchester is one of the most popular deer and target calibres in Britain: accurate, widely available and effective on all UK deer. 7.62x51mm NATO is its military cousin; the two are dimensionally almost identical, but they are loaded to different pressure standards and have slightly different chamber specifications. In practice, .308 rifles are usually fine with NATO surplus, and military-pattern rifles are fine with .308, but the safe answer is to shoot what the barrel is stamped for and to ask a gunsmith if you are unsure.
7. What is MOA, and what does MRAD mean?
Both are angular measurements used for scope adjustment. One minute of angle, MOA, is roughly one inch at 100 yards, and a rifle that groups inside that is described as “sub-MOA”. A milliradian, MRAD or “mil”, is about 3.6 inches at 100 yards and divides more neatly into metric distances. Neither is better; what matters is that your turrets and reticle use the same system and that you know how much each click moves the shot at the distance you are shooting.
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Shotguns and air rifles
8. What is a slug?
Two different things. A shotgun slug is a single heavy projectile fired from a smooth-bore, used abroad for big game and in the UK almost exclusively for practical shotgun disciplines; it is a Section 1 round. An airgun slug is a cylindrical, bullet-shaped pellet designed for high-powered PCP air rifles, offering better downrange energy than a conventional diabolo pellet at the cost of needing a barrel that suits it. Most sub-12 ft·lb rifles shoot traditional pellets better.
9. What is the best cartridge for pheasant, and for clays?
For driven pheasant, most shooters settle on a 30 to 32 gram load of number 5 or 6 shot in a 12-bore, going heavier and larger for high birds and late-season cocks, and moving to bismuth or steel where lead is restricted. For clays, a 28 gram load of 7.5 or 8 shot is the standard for sporting; trap shooters often step up to 7s. The best cartridge is the one that patterns well in your gun and that you can shoot a hundred of without flinching, which is why lighter loads are winning converts in both disciplines.
10. Why do hunters pattern their shotguns?
Because every gun, choke, and cartridge combination throws a different pattern, and the only way to know yours is to shoot it at a large sheet of paper at a known distance and count. Patterning tells you whether your chosen load puts enough pellets into a bird-sized area at your typical range, whether your chokes are doing what they claim, and whether the gun shoots where you look. Half an hour with a pattern plate before the season prevents a lot of wounded birds and a lot of unexplained misses.
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Find ammunition and the guns to shoot it on Rightgun.uk
Rightgun.uk lists rifle ammunition, shotgun cartridges, pellets and reloading components from UK dealers, alongside thousands of rifles, shotguns and air rifles. Check what your gun is chambered for, choose the load for the job and buy from a specialist who can answer the questions this guide has raised.
Further reading: Choosing the right bullet for your rifle, Rimfire vs centrefire, .308 vs 7.62, What is MOA in shooting?, Cartridge selection, Best shotgun cartridges for clay shooting, The UK lead ammunition ban and Airgun slugs vs pellets.
