MK4 Fenn Trap Case Study

David Bennett David Bennett

Case Study and Review – Building A Better Rat Trap – The MK 4 Fenn Trap

Recently, I ran across a great article featuring the Fenn Mark4 trap, published on In the article, the author discusses the legal concerns and potentially dangerous mishaps users may have when prepping the Mark4, and other “body grip” traps.

Using the Mark4 as an example, the author offers a set of concise directions owners may follow to make sure they target pesky varmints, and not their precious live stock, or pets. The instructions include detailed images and textual captions to ensure one can easily follow along.

In addition to providing a wealthy resource on loading the Fenn Mark4, the author also provides measurements and requirements for constructing an artificial tunnel to house the trap. The tunnel serves several purposes. It renders the Mark4 more useful by providing a guide for the varmint to follow right to the bait and trap. Additionally, it prevents live stock and pets from inadvertently triggering the Mark4 – a trap that has the power and strength to injure, or even kill, relatively large animals.

Whether you have concerns about purchasing the Mark4 or Mark6 traps, or you’re already an owner, I highly recommend taking the time to review the full article. The question and answer section at the end also contains helpful tips and information.

Full Article: “Building a better rat trap – The MK 4 Fenn Trap” by


Tags: Fenn Mark4 Setup, Fenn Mark6 Setup, Fenn trap help, Fenn trap setup, Fenn Traps, Mark4, Mark6

5 thoughts on “MK4 Fenn Trap Case Study

  1. The main purpose of a tunnel is to provide a ‘roof’ for the trap to work against. Alan Fenn himself told me many years ago that the main reason why people had foul catches, or empty sprung traps was because they either didn’t have a roof, or one which was too high.

    1. Hello Matt, Thanks for reviewing, taking time providing prudent information, indeed have witnessed MK6 Fenn trap jump 18 inches from a dry fire.
      Your contribution of knowledge, insight, thoughts to the site is welcomed, valued, appreciated and undoubtedly helps community using or considering Fenn MK 4, MK6 traps.
      A blog with be commencing shortly, including requests for people to share thoughts, comments on topics, questions, related to trapping and pest control etc. Have several questions on tunnels and enclosures, hope you have time to review and share more thoughts. Stay tuned!

      1. I will do.

        Regarding tunnels, the most commonly used here in the UK has three sides only; allowing the ground to be used as a ‘floor’ and thereby making a more ‘natural’ feel to it.

        I did a picture tutorial somewhere years ago showing an easy method of disarming the Fenn trap. I’ll try and find you a link. I’ve also got films up on YouTube of Fenns being used to catch Grey Squirrels, just search for ‘Exmoor Trapper’ on the tube.

        Kind Regards,


        1. Hello Matt,
          Thanks for sharing helpful information on tunnels, also must make it lighter weight for carrying and easier overall management accessibility.
          Appreciate direction to search YouTube, “Exmoor Trapper”. If located your picture tutorial of disarming the Fenn trap would serve to broaden knowledge.
          Working on documentation and video for handing Fenn trap, will be available on site when complete. Content is welcomed, will share if permission granted. Thank you for help, support, contribution,

  2. Good Morning Phillip,
    Thanks for message, reviewing the site, reaching out, totally agree writing is time consuming, will take a look at Miftolo’s tools rewriter, please also feel free to email me directly at [email protected],
    Thanks for the interest,

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