Now, I'll be one of the first to say "go ahead and make it" for most things...and I'm known for doing everything the hard way myself, but honestly, unless you're making the barrel to go with it (or perhaps fitting a new plug to an old barrel with odd sizing/threads), I don't see much need in making a breechplug. 
I know not everyone has the ability or desire to make their own parts and I understand completely. The reader here is not, afterall, REQUIRED to buy a mill and a lathe and make a breech plug or lockplate.
But...
The one I made in the above photos was to replace a shop made breech, its not something that can be bought, period. So to do it right it had to be made in house. Owner wanted the breech left in the old barrel for reasons already stated.
Why did the original maker make the plug? Because he is A GUN MAKER and he worked to a standard, he could make a better plug for THAT APPLICATION than he could buy. He would make things in shop, locks and breeches etc if needed because he could make the finished gun LOOK RIGHT and not use some generic part sold by a supplier that will "function" but that's about as much as can be said in certain applications. Its still not possible to buy a good long tang plug so far as I know. I have not even tried in quite some time. Plus he started making guns in the 1950s and HAD to learn to make his own parts BEFORE HE HAD A MILL OR LATHE. There were very few parts available at the time compared to today.
The last 5 barrels I breeched I made the plugs. I did not have to in the case of 2 of them but I did anyway. If I want a short breech plug I would rather have more than 4 threads which may be all you end up with if the plug has a rebate BEHIND the threads. When I make my own I know what they are and they are made the way I WANT. I can make a tighter fit on the threads for example rather than having several thousandths "tolerance". I can make better vent liners than I can buy as another example. I made my own for years anyway because the ones available at the time were made to sell and how suitable they were was secondary. Some parts on the market are made and/or designed by people who don't know siccum about gunmaking but have an idea or a machine setting idle and put it to work to make parts to sell. Or they make parts for someone on order then let the tolerances slip a little...
There are parts available that are excellent and most of us know who the makers are. Some of the generic stuff is pretty grim and often its coin toss as to whether is worth having.
I have used precarves, but usually regret it. In trying to make a Vincent Ohio rifle once on a budget for a guy I knew I sent back 3-4 precarves in a row. The 4th/5th only had a screwed up lock inlet and I gave up and MADE a lock plate to fit the hole.
The supplier was stuck with a guy cutting this pattern who, the supplier told me frankly, did not much give a @!*%.
It turned out fine in the end and the friend who now owns now it really likes the rifle.
But in the end I could have made it from a blank cheaper I suppose.
One of the reasons for a site like this is to diversify peoples understanding and skills.
There is little skill needed to pick up a catalog and ordering a bunch of generic parts the supplier recommends and a preshaped stock. A good serviceable, even a fine rifle can be made in this way. But it will not be especially unique if the viewer can tell which precarve was used from across the room.
Demonstrating how to do the hard stuff, even if the reader will never do the work, is the value of forums such as this.
If the reader has a project or encounters one that requires a breechplug that he cannot buy knowing that a two piece "plain breech" with a high temp silver soldered tang will withstand decades of hard service opens a door that allows him to make the breech plug/tang he needs with the tools at hand in most shops. With surprisingly little work.
Dan
