You do have to remove the stock in order to adjust the trigger. The adjustment tool for your rifle will only go in one place so don't be intimidated by it.
As far as the stock goes, I have never had a problem with a proper amount of torque to be placed on a stock. I would still buy an inch pound torque wrinch to have, but if you want to adjust the trigger, don't be afraid take the stock off. Just make the screws snug back on the stock so as not to allow the screws to easily back out.
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