A MA­TE­RIAL DIF­FER­ENCE Re­plac­ing old leather pis­ton seals with mod­ern syn­thetic al­ter­na­tives? Jim gives it a shot

Airgun World - - Technical Airgun -

Be­fore the ad­vent of syn­thetic pis­ton wash­ers and ‘O’ rings, pis­ton seals were made from leather and in some ways, it’s not a bad choice of ma­te­rial; it’s read­ily avail­able, fairly cheap, and flex­i­ble enough to form a good air seal with­out ex­ces­sive fric­tion, but it does have one ma­jor draw­back, which is that it dries out and be­comes in­flex­i­ble af­ter re­peated shot cy­cles in the high tem­per­a­ture en­vi­ron­ment of the springer cylin­der.

In or­der to ex­tend the life of leather seals, some means of keep­ing them soft and sup­ple was needed, and the tra­di­tional so­lu­tion was a fat ex­tracted from the shin bones of cat­tle and called ‘neats­foot oil’ – ‘neat’ be­ing an old word for ‘cat­tle’. Un­like other an­i­mal fats, neats­foot oil re­mained a liq­uid at room tem­per­a­ture, which al­lowed it to soak into the leather, and this greatly ex­tended the use­ful work­ing life of seals, but in time, and es­pe­cially in the high tem­per­a­ture en­vi­ron­ment of the springer cylin­der, it ox­i­dises and be­comes brit­tle.

In or­der to ex­tend the use­ful work­ing life of leather seals, airgun man­u­fac­tur­ers used to rec­om­mend pe­ri­od­i­cally – af­ter ev­ery so many hun­dred shots – putting a couple of drops of lu­bri­cant (usu­ally their own brand) down the trans­fer port.

In springers that achieved very low muz­zle en­ergy, such as 6 ft.lb. tar­get ri­fles, neats­foot

With the lit­tle Sim­mons White Tail Clas­sic 1.5-5x20mm scope, the HW55 is a per­fect short-range ri­fle.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.