Do the Safety Function Test.
Yeah, I got the Boyds c/w handguard a few years ago. I was able to transfer all the hardware onto the Boyds (except for the front sling swivel-- I out-sourced that.
It was delivered on time and looks good--very much 'new military'. Aside from a bit of minor fitting work, it was a drop-in. I needed to thin out the rear part of the handguard just a bit to allow it to seat properly, and also to sand a bit off where the bottom of the trigger group seats onto the underside of the stock (sand the wood, not the metal part).
NB Be absolutely certain that the reassembled weapon passes the Safety Function Test by holding the trigger back while you charge the rifle.
Once the bolt is returned to battery, release the trigger. You must hear a 'click'. Then press the trigger again. If the hammer does not release...that means the sear has failed to catch the hammer at the top of its travel, and it's followed the bolt until it struck the firing pin.
This is a dangerous condition which may result in a round (or more) being discharged unexpectedly. This is often caused when the trigger group is not seated properly. That's why it is important that you sand that area of the stock. There is an optimum amount of tolerance there--too little is dangerous, yet too much is sloppy, so work slowly and perform the Function Test often until it's...just...perfect.