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Old 08-05-2019, 12:28 PM
hara-julu
US Air Force

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Put an 7-2 in an 7-4 stock (trigger mod)



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I have done two of these now and something like a process is forming, will share. I am a tinkerer, not a machinist, engineer or smith. The mechanics of these 7-2 triggers are pretty simple, but all caveats apply, if you are in any way not comfortable with firearms modification, read for entertainment only.

So the 7-2 is an really fun rifle, the paddle action is the defining feature, nice trigger is next (imho) and the bull barrel with recessed crown is third. The small birch stock however is not in the same class as the hardware it holds.

Thankfully its big sister the 7-4 has a strong following in the biathlon community, which is where I crossed paths with my first 7-2. Stocks for an 7-4 are plentiful and varied and more importantly available for purchase. Unless you are one of the supremely talented folk making stocks on this site, you are out of luck.

The bear stock is one of my favorites (and what I run), a bit expensive and there are many options: Lost Nation, Larsen, Biatar...



So the reason one can not simply get a 7-4 stock and jam in an 7-2 action is trigger placement. THe trigger on an 7-2 is extended from the rear of the trigger assmbly and will want to be approximately where your neat new palmswell is occupying on that new stock. No joy.

Here is an 7-2 action, not the trigger coming from the rear of the trigger assmbly



Fortunately, all the other measurements are the same between the 7-2 and 7-4. Mounting lug locations? yes, contact points, yes. Magazine location? yes. Paddle clearance? yes. Just the trigger location (and safety) are different (and dry fire mechanism, more later)

Here is a picture with the mag well lined up of the trigger guard from an 7-2 below against an 7-4 stock with an modified trigger (my first attempt)



So the trigger needs to extend directly south of the trigger block. THe trigger is a simple lever with a pivot point, drift out the pin and have a look:



So a cut here and a grind later the trigger is now a stub. It is important to leave the rear segment for about 1/4" as this will impact the rear of the trigger frame as an over-travel control.



You can see an trigger I ground up from an 170 year old iron nail, surplus from an ongoing remodel.

The trigger is fit pretty snug and devcon does the rest. I am careful to leave a little extra devcon on the bottom to "build" some additional lateral support. An real machinist could use threading or alternate mechanical approach but I warn the trigger is of unknown material, feels like an steel something alloy, pretty light and I fear would melt away under any real heat.



A simple rig to hold everything square during gluing goes a long way.

So from here it is reassembly (and a few turns on the trigger spring adjustment to get the pull nice and light) and we can see the trigger is now oriented correctly.



Oh, right, grind of the extra!



And drop it in the fancy new larsen stock:



Go race!

(If you are in new england, we race at HSC Biathlon in Harvard MA, pm me and come on out)
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