• How to MOD your MK V Trigger.

    Here are the instructions about how to replace the trigger spring on a Weatherby MK V.
    The MOD will cover all 9 lug Weatherby Rifles from 257 Weatherby Magnum and up to the 460 Weatherby Magnum.
    Please be aware that this info is NOT for the 6 lug version of the Weatherby MK V.
    This instructions can be used to replace or to mod the original spring.
    To cut the spring is something that is out of the hands of both Weatherby.dk and Weatherby.
    So if you do so, it is on your own risk!

    First, the tools needed for the job. Trigger assembly, new spring and a mandrel.
    A hammer and some thin oil will also be handy.
    A Weatherby deskmat under the parts is a matter of course!



    Tap out pin #1:



    Pin gone, now remove "sear" part, by tapping out pin #2:



    Here is pin and the sear removed.
    Now remove the spring, and the disk below the spring.



    Tap out pin #3 and pull the trigger backwards, while you are holding your other hand over the bolt stop pin/spring.
    If not, the pin/spring will fly a feet or two...



    Now there is only one part left, the trigger spring.
    Have a look in the front of the trigger housing, you should be able to see the spring.
    Use a small screwdriver and get it UP through the hole.
    DO NOT try to remove the slottet unbrako to pull it down. It won't work!



    To the left is the old spring, to the right is the new one.


    The original spring is often grinded in the ends to make a flat surface.
    There is no need to grind the new spring, and for safety reasons don't!


    So, it is time to put the trigger back into order. Replace the spring, insert boltstop with spring.
    Insert trigger from the rear, check that the trigger spring is in place and not bended by the trigger.
    Make sure the front of the trigger is OVER the spring.
    If the spring gets bended, adjust it with a small screwdriver. Loosening the slotted hex in the bottom will also help a bit.
    Now, slide the trigger further forward, so the boltstop is resting in the trigger fork.



    Insert pin #3.
    Then insert the spring with the disk in the bottom.
    A small amount of grease/oil on the disk, will make it stick to the spring.
    So it will be easy to get into place.
    Now, press the sear down on the spring, align the holes and insert pin #2.
    This is the most difficult part of the job.
    Here it is done:


    Press down the sear and insert pin #1.



    DONE!!!
    That's all folks, hope this was easy to understand.
    Best of luck while gunsmithing your Weatherby!!!
    Comments 35 Comments
    1. Buano's Avatar
      Buano -
      Thanks everyone. I just ordered the trigger spring. If it works as well as it looks like I'll be ordering on for my A-Bolt Stainless Stalker next.

      If only I knew a source for titanium springs!
    1. ruffcountry's Avatar
      ruffcountry -
      I did it ! Bought the recommended spring and replaced the one in my .300 Euromark also did the polish while I had it apart . Went from about 5lbs to just under 3 lbs . Might still be the slightest amount of creep . Thanks so much for this helpful info .
    1. 11 Charlie's Avatar
      11 Charlie -
      Brilliant 340 Weatherby! I was lamenting not being able to adjust my Mark V trigger very low and not being able to get a Timney when I decided to try your tutorial. Thanks for the factory/after market spring picture as it confirmed my taking 1 and 1/2 coils off the factory spring was OK. I also carefully adjusted the sear to get a tiny bit of creep out of it. After 24+ bolt slams/drop tests I now have a creep free, perfect breaking, sub 1 pound pull! Better than what I thought I was going to get as I only target shoot anymore. If by some chance I ever go hunting again I can always adjust some weight back into it. Thanks again 340 Weatherby for showing what a premium trigger Weatherbys come with! Good shooting and God Bless! Bob
    1. 340 Weatherby's Avatar
      340 Weatherby -
      Thanks a lot 11 Charlie for the kind words!
      I have tuned a pile of them for friends of mine.
      Actually I have one to fix this weekend.
      Comes from a Jap 257Weatherby, and is promising as is.
    1. Parke's Avatar
      Parke -
      Awesome information!
    1. calvin17d's Avatar
      calvin17d -
      Hey guys great thread..... Just bought a spring from Ernie for my Mark V and it is actually a small amount longer than the stock spring.

      Concerns?
    1. Mike300wby's Avatar
      Mike300wby -
      Can't get the 2 screws loose that hold the trigger assy. To the action. Starting to strip the heads. Do I need to add some heat? I assume the factory has screws so I can replace once I get them out.

      Mike
    1. Broz's Avatar
      Broz -
      A good fitting screwdriver and some valve lapping compound on the tip if you have some. Also try a nice flat punch and give the screw a good tap.

      Jeff
    1. 340 Weatherby's Avatar
      340 Weatherby -
      Quote Originally Posted by JaimeChinook View Post
      When I ordered my spring, I noticed the description said it was for "current US manufacture"...
      It seems like Weatherby had a thinner spring on the first Jap triggers. I found a spring that was from an old Jap rifle. The spring was only 3.3 mm (0.130") vs. today they are around 3.8 mm (0.150")
      so it's correct. The rifle serial number was 76xxx. I have also been made aware of the Canjar set trigger for Weatherby uses the smaller spring.
    1. Uncle Jimbo's Avatar
      Uncle Jimbo -
      Performed this mod on my .300 wby Accumark using the "Ernie the gunsmith" replacement spring. Thank you for this write up! The spring swap was simple and my trigger pull went from 3.5# minimum to 1.5# minimum. I adjusted it up to 2# which is where I like my hunting rifles.
    1. Mike300wby's Avatar
      Mike300wby -
      My 1982 Japanese mfg also had a different diameter spring.

      Mike
    1. Mike300wby's Avatar
      Mike300wby -
      Any source for the triggers that use the smaller springs, & what size to get?

      Any other trigger options?

      Mike
    1. 340 Weatherby's Avatar
      340 Weatherby -
      No clue where to get a smaller spring. The only other option I know of is Timney.
    1. Yoder's Avatar
      Yoder -
      I finished this on my gun the other day. Worked great. Thanks!
    1. 340 Weatherby's Avatar
      340 Weatherby -
      Great, I'm glad this post has helped a lot of Weatherby owners!