As mentioned last week, the rules pertaining to the jack are strict. Every jack must conform to BCGBA standards and be tested regularly. When tested they are stamped with the tester’s mark and the year of expiry.
Matches must be played with jacks which are in date. If played with non-legal jacks, the games are void and must be restarted.
References From The Laws Of The Game
A.1. The game shall be played with standard Jacks of 2 full bias as approved by the British Crown Green Bowling Association. Jacks manufactured after 1st March 2004 shall be black or yellow in colour. They shall weigh 666grams plus or minus 10grams. The width shall be 90.5mm plus or minus 0.5mm. The height shall be 98mm plus or minus 0.5mm.
A.3. New and renovated jacks shall be stamped consecutively with the year of expiry and for this purpose the year shall be reckoned from 1st January to 31st December. All jacks shall be re-tested at not more than seven yearly intervals. Jacks manufactured before 2004 must comply with the 2004 requirements.
A.4. Jacks are not to be stamped on more than four occasions. The first three, in date order, to be made on the bias side with the fourth and final one being made on the non-bias side. The expiry date on that stamp will indicate the year after which the jack is no longer legal.
2.7. If during the course of a match, any jacks are found to be not in accordance with Appendix. A, the affected games shall be declared void and restarted with standard jacks.