7mm WSM build - things to consider

Discussion in 'Gunsmithing' started by One_Duck_Limit, Nov 17, 2010.

  1. One_Duck_Limit

    One_Duck_Limit Well-Known Member

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    I am thinking about building a 7mm WSM. The donor action is a Rem 700 Long with a magnum bolt face. The original chamber was 7mm Rem Mag.

    Are there any modifications that need to be done to the action to make this work?

    Those of you that have a 7mm WSM and shoot Berger 180 VLDS what speeds are you getting and how long is your barrel?
     
  2. JeffVN

    JeffVN Well-Known Member

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    What are you going to use it for?

    I have two 7WSM; both run the Berger 180s out of 9 twist barrels:

    I have a tactical 7WSM with a 26" Kreiger; it runs at 2,920 fps all day long.

    For F-Class use my 7WSM wears a 30" Bartlein and finds 3,050 easily reachable with no pressure issues in the Las Vegas Summer. The wind hold at 3,050 is stunningly small. I love it.

    I run RL-25, H1000, H 4831SC. RL-25 does not like the Las Vegas sumer, but ran like a champ in Houston, TX. H100 is my tactical rig powder of choice. H4831 is my F-Class powder of choice.

    JeffVN
     

  3. DMCI

    DMCI Well-Known Member

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    I built mine on a new WIN 70 CFA in 300 WSM. This is a better approach in my opinion because action was designed to handle larger case from the git go. No bolt section reduction required to handle Jeffrey case. Gunshop purchased barrel, stock, trigger group. This paid for more than half the cost of donor rifle. They keep parts for people with damage rifles or worn barrels.

    Put Lilja 3 groove 26" varmint pattern barrel on rifle and what at the time was the first production MacMillan stock for that action. Jewel trigger rounds out package. 26" barrel gives a little more velocity, but is pain in gun safe not designed for same. :) Had USO make custom picattinny rail for rifle. Initially had 3.2-17x44/58 shown, now has 3.8-22x58. Gives touch more power and better low light function.

    Rifle fires 180 VLD Berger fairly accurately using F215M primer and VV N165 powder. Velocity with 180 around 2830 or so. see 100 yard development target below.

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    Last edited: Nov 17, 2010
  4. J E Custom

    J E Custom Well-Known Member

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    The main thing to watch for is the case touching the bolt rim because of the rebated rim.
    (It is bigger than the bolt rim dia. and can interfere with getting a true headspace).

    I allways put a small chamfer on the inside of the bolt face rim to clear the case body
    and make sure the case head sets on the bolt face not on the case body.

    The rest of the build should be normal.

    J E CUSTOM
     
  5. One_Duck_Limit

    One_Duck_Limit Well-Known Member

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    This will be my long range hunting rig.

    I have a barrel on order. It will have a 1:9 twist and finish at 28".

    What about the magazine box? I did a bit of reading last night and it looks like the feeder rails will have to be opened up. Do I need to replace the follower?
     
  6. J E Custom

    J E Custom Well-Known Member

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    I always use a center feed mag box and a flat top follower.

    The center feed box makes it easy to tune (You can bend it in or out)

    The rails will have to be opened ether way.

    J E CUSTOM
     
  7. toader

    toader Well-Known Member

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    Watch the feeding system - the WSM don't like to feed sometimes!!

    Use a center feed like J E stated & make sure it feeds with a few in the mag.
     
  8. One_Duck_Limit

    One_Duck_Limit Well-Known Member

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    Thanks for the info.

    One more question. Will the mag capacity be reduced due to the larger diamater case? Will I go from a 3 mag capacity to 2?
     
  9. DMCI

    DMCI Well-Known Member

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    I used a .300 WSM Winchester Controlled feed action. I also got one of the first MACMILLAN A5 Stocks for that action. Should be no change from factory WSM action. This was not a recut of a 300 WINMAG Action.