Hi,
No commercially produced Brown Bess reproduction made today is authentic or representative of the workmanship found on original British muskets. Your musket is probably what they sell as a "pattern 1748" musket. You can make it more authentic by getting rid of the lock moldings, thinning them dramatically, changing the trigger guard for the proper style not the 1730 style, reshaping the tip of the ramrod correctly, replacing the nose cap with one shaped and installed correctly, and trimming down and reshaping the carved apron around the barrel tang. The lock will have to be worked over to bring it up to a standard expected of the originals. Even with all that work, you will still have issues. Measure the outside diameter of your barrel at the breech. The originals were 1.35-1.42" in diameter. The outside diameter of the muzzle should be 0.91". I'll bet your barrel is barely 1.09" at the breech and about 0.88" at the muzzle. Those dimensions change the entire architecture of the gun.
Part sets from TRS are about the best you can do with respect to authenticity. They are cast from originals and generally have the correct dimensions albeit sometimes slightly smaller likely due to shrinkage during casting. The barrels are very close to the originals and you can build up the locks into ones that are historically correct and made to the original high standards. Here are a couple of Bess locks I made that would pass muster with British ordnance. Take your lock off and compare it with mine.
Now look at the inletting in your lock mortise and compare it with this done the way they were originally made.
Here is the mortise on an India made short land Bess that we recently repaired.
My example is a pattern 1730 so the carved lock moldings are appropriate unlike all later pattern Besses. Note how thin the flat surrounding the lock is and no need for that ugly notch to clear the flint cock. The precarved stocks supplied with TRS sets are usually pretty authentic but the machine inletting of components like ramrod pipes and butt plates can be off a bit. On the pattern 1742 parts that I recently ordered, I asked that the stock only be fitted for the barrel and ramrod, and roughly profiled. No other machine inletting. We will see how it goes.
dave