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Giant Hand-Forged Antique “P” Lock (Screw-key Lock)

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Posted 2 years ago


(32 items)

At over five inches long (without the key), this is a very large P-lock (the reason for the name is obvious); the average one is one to two inches shorter. P-locks are also known as “smokehouse” locks, “barn door” locks, etc. but of course they could have been used to secure anything with a large enough hasp. They are a type of “screw-key” lock. The bolt in a screw-key lock sits lengthwise within the cylindrical body. It engages the shackle either with a notch as this one has (pic 2) or by means of a hole in the shackle through which the bolt passes. The bolt is held in place by a spring. The opposite end of the bolt is threaded and when the key (having threads on its inside) is screwed onto the bolt it draws the bolt back allowing the shackle to swing open. The third picture shows the male threads on the bolt and female threads inside the barrel of the key. P-locks are fairly simple compared to padlocks and could have been made by any reasonably skilled blacksmith. The tiny brass P-lock in pics 1 & 2 is a fully functional 7/8” long miniature I made.


  1. blunderbuss2 blunderbuss2, 2 years ago
    You made that replica Ron ? I'm impressed. Maybe not as much as the .50 in your profile pic. ! U dun good, mon.
  2. UncleRon UncleRon, 2 years ago
    Thanks, bb2. I enjoy making things. Despite the occasional frustration when things don't seem to want to go as planned, it's very therapeutic.
  3. AzTom AzTom, 2 years ago
    I love the little one you made.
    How do the keys differ so that one key doesn't open all the locks made?

    As a heads up to beginners, there are some repos out there that look very much like the real thing.
  4. blunderbuss2 blunderbuss2, 2 years ago
    There are holes for the key at opposite ends of the barrel ? Still trying to completely understand the mechanism, as I've never seen one.
  5. UncleRon UncleRon, 2 years ago
    Yes there are repros but they tend to be made of sheet metal and usually have obviously accelerated rusting on them.
    The only differences between the keys is their diameters and the threads-per-inch on the bolts. Many are similar and somewhat interchangeable.
    BB2 I’ll try to explain: Imagine the body as a simple cylinder. Solder a washer, with a square hole, at the center of the inside of the cylinder. Now imagine the bolt as a rod, with a washer soldered on it in the middle, with threads on one side of the washer and filed square on the other side. Put the rod into the cylinder so that the square part goes through the square hole (you need something like this arrangement to prevent the rod from rotating – it moves back and forth but can not turn around) and push it in until it touches the washer with the square hole. Now, think of a spring the same diameter as the INSIDE of the cylinder and somewhat bigger than the threaded end of the rod. Put the spring inside the cylinder (it now encircles the rod's threaded end) and close that end of the cylinder with a cap which has a hole in it slightly larger than the threaded part of the rod. The rod is now trapped inside the cylinder, and held against the washer in the center of the cylinder, by the spring. The key is a shaft with threads on its INSIDE and a washer soldered onto it at such a distance from its end that when the key is put through the hole in the cap, and screwed onto the rod, the washer on the key screws down until it touches the cap and the key can’t go in any further. However, if you continue to turn the key it draws the rod back inside itself, compressing the spring, and of course the opposite end of the rod (bolt) is drawn out of the notch in the shackle.
  6. blunderbuss2 blunderbuss2, 2 years ago
    Guy has 150 rds of .50 BMG cases for $75 in Lexington, KY if you are interested.
  7. Windwalker Windwalker, 2 years ago
    Very cool lock ..love the history behind it as well..thanks for sharing..

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