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BT100 Hammer Spring Life Cycle Data

Discussion in 'Uncategorized Threads' started by IndyJohnO, Oct 1, 2008.

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  1. IndyJohnO

    IndyJohnO TS Member

    Jan 29, 1998
    BT 99 and 100 Hammer Spring Life Cycle

    SITUATION: After a number of months of 100% primer ignition, the primer ignition failure rate gradually increases to 4 out of 25 shells during a 30-day period. Then failure rate gradually increases.

    When light firing-pin-to-primer hits result in consistent primer ignition failure, the cause is almost always a weak hammer spring. Replacing the hammer spring corrects the situation. Although powder residue in the firing pin hole can contribute to the failure rate.

    10,000 Targets/Year Hammer Spring Life Cycle Data (Spring Replacement):

    2 yrs/7 mos

    3 yrs/1 mo

    2 yrs/4 mos

    Hammer spring was never left over night "cocked" under tension. The measured length of the replaced spring and the new spring (neither under tension): the replaced spring is usually 2 coils shorter.

    RECOMMENDATION: Replace the BT 99 or 100 hammer spring every 2 years. The top-lever spring life cycle is the same. Replace it at the same time. Both cost $4.25 each and are easy to change.

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