How Much Does Temperature Change ELEY’s Velocity Between Summer and Winter?

ELEY’s guidance on scale is this: in some countries, extreme heat changes velocity dramatically, of the order of 30-40 ft/s. That figure describes genuinely extreme heat, not the difference between a mild and a chilly club night, and it is not a per-degree coefficient you can apply to any temperature swing. There is no published ELEY velocity-change-per-degree figure, so be wary of any source that offers you one.

What ELEY does publish is a velocity band for every product, the mean velocity recorded for your specific batch during proof testing, and a dedicated cold-weather product range engineered for genuinely freezing conditions. If you shoot across a wide temperature range, the practical answer is not a correction factor. It is to test in conditions representative of the ones you compete in.

How Big Is the Effect?

Extreme heat is the one case where ELEY puts a number on it, and 30-40 ft/s is that number.

Read it for what it is. It is indicative, it describes extreme heat rather than ordinary seasonal variation, and it is not divided by degrees. The same 30-40 ft/s cannot be scaled up or down to a temperature difference of your choosing. It is there to tell you the order of magnitude at stake when ammunition is shot, or stored, in real heat.

It is also worth putting alongside the published bands below. ELEY tenex, match, team and club are all specified at 317-330 m/s (1040-1085 ft/s), a band 45 ft/s wide. Extreme heat can therefore move velocity by something comparable to the full width of the specification. At 50 m that is a manageable amount of vertical; at extended distances it is not something to discover during a match.

The Mechanism, Briefly

Propellant is a chemical system, and chemical systems are temperature sensitive. The temperature of the cartridge as it sits in the chamber affects how the charge ignites and burns, and therefore how quickly pressure builds behind the bullet. A round fired on a cold winter morning has not become different ammunition, only the same ammunition burning under different starting conditions.

Lubricant is the second temperature-dependent element. ELEY’s lubricants differ in hardness at any given temperature: beeswax-tallow is softer, thicker and stickier, paraffin thinner and harder with a higher melting point. Because the purpose of .22LR lubricant is to ease repeated chambering, its behaviour at temperature is a chambering question rather than a velocity one.

The Published Velocity Bands

Every ELEY product carries a published velocity band rather than a single number. The premium flat-nose family sits in a deliberately narrow band:

That band is achieved by controlling the inputs: propellant measured electronically for each individual cartridge, cases of uniform length in a tightly controlled brass alloy, exacting crimping standards for optimum pull-out force, and priming in an air-conditioned facility that gives a 75% improvement in the spread of primer weights compared with other manufacturers.

What the Number on Your Box Actually Is

The lower line of an ELEY batch code is the mean velocity across four barrels during proofing. In the worked example 10 26-04 244 over 1045, that is the 1045.

It is a mean, averaging four different barrels, none of which is yours; and it was measured under proof conditions, not on your firing point in February. Treat it as a reliable comparative marker between batches rather than as a prediction of what your chronograph will show on a cold day. A batch proofed at one end of the band is genuinely different from one proofed at the other.

The Cold-Weather Engineering

Rather than publishing a temperature correction, ELEY engineers products specifically for the cold.

ELEY tenex biathlon, launched in 2012 on the tenex platform, exists because examination of bullet and chambering characteristics at freezing temperatures showed the standard cartridge could be improved for those conditions. It carries:

• A scientifically designed cold-temperature lubricant, with the box stating lubrication for use to -20°C, engineered to enhance consistency, reduce barrel wear and maintain accuracy in freezing temperatures.
• A reduced cartridge diameter, to aid cycling in bolt-action and straight-pull biathlon rifles.
• An increased propellant charge, giving enhanced terminal energy and greater knock-down force for the biathlon target, and with it a velocity band of 335-354 m/s (1100-1160 ft/s), above the standard flat-nose range.

ELEY biathlon club applies the same thinking at club level: refined bullet and case design for reliable cycling in extreme winter conditions, a specialised cold-weather lubricant and an increased propellant charge.

That a dedicated cold range exists at all is the clearest statement of ELEY’s position: temperature matters enough to design for, not enough to reduce to a single correction factor.

The Bottom Line

Extreme heat can change velocity dramatically: ELEY puts it in the order of 30-40 ft/s in the hottest countries. That is an indication of scale for extreme conditions, not a per-degree figure, and there is no published ELEY velocity change per degree to work from. Use instead what is published: the velocity band for your product, the four-barrel proof mean printed on your box, and the free proof data for your batch at eleyxshot.com.

Then settle it properly. Test in conditions representative of your competition, and book batch testing through your own barrel at eley.co.uk/vip. For genuinely freezing conditions, look at the biathlon range, lubricated for use to -20°C.