Bnail, I have never found one lock to be anymore difficult to inlet than another, as others here have said. However, geometry of where it is inlet is very important, and needs thorough consideration before chisel contacts wood. Most barrels I have seen are threaded for a 1/2" breech plug, and this usually means your lock will be further forward than historical arms had it. In the past I have slightly modified the plug to get the touch hole as far back as possible.
However, in this month's issue of "
MuzzleBlasts", there is an article entitled "My Masterpiece" by Mr. Hugh Toenjes. in which he shows a diagram of a breech that has been modified to correctly position the lock. This, IMHO, is a safer alternative to using a shorter plug, and also provides some room to sneak a bit of powder behind the ball in the event you dry ball the rifle. I am thinking I may try this with my next rifle.
Great article, BTW Mr. Toenjes.
M. E. Pering