"GearBox" for Browning® Buck Mark


(135 reviews) Write a Review
0.30 LBS
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"GearBox" Installation Instructions for the Browning Buck Mark


At a glance:

  • Upgraded sear spring lowers trigger pull weight by .5lbs or more!*
  • Installation frame houses spring for easy installation and consistent sear engagement
  • No need to experiment with DIY spring fixes - one simple drop-in replacement!


The Browning Buck Mark has a great trigger right out of the box. But if you’re like many Browning Buck Mark owners, you’ve likely researched ways to lower the gun’s trigger pull weight and adjust the feel even further.

There are many DIY solutions out there, including the well-known “Heggis Flip” or Buck Mark sear spring flip. But these solutions can be complicated to perform, provide inconsistent results and can cause potentially dangerous issues with the fire control system.

Put an end to DIY fixes with the new “GearBox” for Browning Buck Mark from TANDEMKROSS! The “GearBox” is a simple, drop-in replacement for the factory Buck Mark sear spring that makes installation easier and lightens the trigger pull weight.

The “GearBox” comes complete with a redesigned torsion spring housed in a polymer installation frame. The frame captures the spring for easy installation and then, once installed, works as a guide for the spring, ensuring proper alignment and consistent engagement with the sear.

Simplify your trigger upgrades and install the TANDEMKROSS “GearBox” today. Pair with a Browning Buck Mark “Victory” Trigger for ultimate performance!

*Individual trigger pull weight results may vary.


*Fits all Buck Mark models including the Buck Mark Rifle

135 Reviews

  • 5
    GearBox for Browning Buck Mark

    Posted by Al Sypniewski on 4th Aug 2023

    I am not a gunsmith so I was a little concerned about my skill to replace the sear spring. The GearBox made it quite simple after I watched the installation video. Provides a very crisp break; already had a Victory trigger. I'm very pleased with this purchase.

  • 5
    Works as advertised

    Posted by Chaos Customs Inc on 17th Jul 2023

    It lightens the trigger pull, and makes reassembly easier. I've installed these on two customer's guns so far, both are very pleased.

  • 5

    Posted by Mark Creech on 14th Jul 2023

    If you own a Browning Buckmark and you want to make one change, the Gearbox from Tandemkross is your #1 choice. They have many easy to install products this is one of my favorites!

  • 5
    Browning Buckmark Gearbox

    Posted by James Hill on 31st Oct 2022

    Easy install. Replaced Heggis flip. Increased my trigger pull weight very slightly, but made it feel more crisp and with less pull to pull variation. Worthwhile upgrade.

  • 5
    Gearbox Browning buckmark

    Posted by Vincent on 18th Aug 2022

    Quality part, easy to fit. Definitely lightens trigger. I Recommend this

  • 5

    Posted by Demoniakkin on 18th Jun 2022

    Livré en moins de 15 jours pour équiper mon Browning Buckmark field target. Installation en moins de 2 minutes (démontage inclus). J'étais sceptique : poids de détente réduit à 1,15kg au lieu de 1.85. Aucun incident de tir (alors que le flip Heggis me donnait une non percussion sur deux). J4ai testé sur 150 cartouches de CCI standard. Vient compléter l'extracteur, le percuteur et le halo ring de tandemkross. Que du bonheur ! Je recommande vraiment cette pièce.

  • 5
    This is awesome

    Posted by Joe on 19th May 2022

    This gear box works awesome I am still using the stock gold trigger because I like the look of it and I do notice a big difference. I didn't expect the trigger to feel this light with the stock trigger. I've had my buckmark since around 2004 so the difference in pull is very noticeable with the gearbox installed and it was easy.

  • 5

    Posted by Ken on 18th May 2022

    Very easy to instal and big difference in trigger pull. Will shoot it tomorrow for live fire test.

  • 5
    Trigger pull under 2 lbs

    Posted by John on 10th May 2022

    This along with the Tandemkross trigger helped lower trigger pull from just above 4 lbs from the factory to just under 2 lbs. Highly recommend.