Cast Springs

Please note that this is for guidance only, there may already be a
tried and tested method that you have previously used on our
springs and if so there is no need to change.
We cannot accept any responsibility for any breakage during the dressing or fitting of any spring/s, we do offer a fitting service , please ask if required. However should a breakage or malfunction arise and the spring is considered suspect for fault then please return to us for inspection.
If at any time you harden the spring unintentionally when making adjustments then simply heat and cover to allow to cool slowly.
*Suitable eye protection should be worn at all times when handling or fitting springs*
Note above safety advise
Normalise the spring by heating to red and holding in flame for one minute, remove flame gradually so as to cool spring as slowly as possible, alternately remove flame and cover spring in ceramic blanket or similar until cool. (the use of Oxygen and Acetylene is not recommended as the heat can be to intense)
Allow spring to cool.

Use runner (if any) to grip for light cleaning of casting any file marks running across the spring should be removed, this will eliminate the chances of breakage.(Any marks should ideally run the length of the spring)
Remove the runner and clean up runner area.
Ensure that spring will position flat on the lock plate and that the hook / link/ top leaf will engage correctly on the tumbler / Frizzen toe / Sear bar. Any correction to the seating of the spring should be undertaken at red heat.
Open spring (at red heat) to the desired "set" allow approximately 1/8"/ 3mm extra to allow for the set bedding in once tempered.
Heat spring to cherry red and quench in a suitable spring tempering oil.(Remember at this stage the spring is extremely brittle).
Clean up and temper by…….
1/ In a controlled oven at between 400 - 480 degrees centigrade for approximately 1 hour, remove and allow to cool.
2/ Place spring in tin (steel or Stainless steel) and cover with tempering oil, heat tin from underneath as evenly as possible and allow the oil to ignite.(flames may be quite vigorous so care should be taken).When the flame appears to die down the spring can be removed from the tin and allowed to cool. (always remove before all oil has burnt away so as not to over heat).
When fitting spring use a suitable spring clamp and wear eye protection (see above *).
Bed in the spring by compressing gradually, On main springs onto half cock and leave for a short period before going onto full cock.