How To Replace A Shotgun's Hinge Pin
September 23, 2010
There are some gunsmithing jobs that I really enjoy. They aren't necessarily the high-dollar jobs or even the quick and easy ones--though I sure do like to see some of those from time to time to pay the rent and keep my wife happy.
The hinge pin is located at the front of the receiver, and the barrel pivots on the hinge pin when the action is opened.
The jobs I like most are the ones where the owner will see a dramatic difference in his gun after I've finished with it.
For example, I remember a number of years ago, an older fellow came into my shop with what had to be one of the most beat-up, worn-out single-barrel shotguns of all time. All he wanted me to do was make it like new! I was concerned about that because of the work involved, and I let him know that the cost of repair would be far in excess of the value of his gun. It seems the gun had belonged to his grandfather, so the actual value was of no importance. The owner was a successful businessman in the community, so he had no problem with paying for the work.
The gun was an inexpensive single-barrel, break-open 12-gauge shotgun probably made around 1900. I don't recall the name stamped on it, but it definitely wasn't a major brand. Besides mechanical problems, a broken stock, and a rusted metal finish, the barrel was loose as a goose. I could hold the gun in one hand, shake it, and watch the barrel move in the receiver. This was of special concern to the owner and to me. To make a long story short, when the owner picked up the gun from me after I had worked on it, aside from all the other needed repairs and refinishing, the barrel locked up in the receiver as tight as a bank vault. The owner was delighted and couldn't believe it was the same gun. He thought I was a magician! It was an impressive repair, if I do say so myself.
Many old single-barrel shotguns have loose barrels. In fact, it's pretty common. On many old guns, you can easily move the locked barrel from side to side and sometimes up and down as well. If you can move the barrel up and down, that's an indication of wear on the locking lug or on the locking lug recess on the barrel. If you can move the barrel side to side, that indicates wear on the hinge pin or on the hinge-pin contact surface of the barrel lug.
Not too long ago, I picked up an old Harrington & Richardson Topper Model 48 single-barrel, 16-gauge shotgun made in 1945. The gun was in fairly nice shape with a good, solid walnut stock. The only problem was excessive wear on the hinge pin. Because of this, the barrel would move from side to side when locked.
Before getting into how you make this repair--and it's really simple and easy--let's take a look at what you don't do. Over the years, I've seen many shotguns on which someone had taken a center punch and made a series of punch marks inside or along the outside edge of the hinge pin contact surface of the barrel lug. The idea was to move metal back against the hinge pin and tighten up the barrel. It would work for a while, but sooner or later, those punch marks would flatten out, and the barrel would be loose as well as disfigured by the punch marks. That's a bad practice--one I wouldn't recommend.
The way I make the repair is to replace the hinge pin. If your gun is like my old H&R, the original hinge pin is nothing more than a solid pin pressed into the receiver. With a simple pin like this, it only requires a few basic hand tools to do the work. If your hinge pin is more complex and is threaded or has through-holes for part of the ejector mechanism, then the job becomes more difficult. Until you've replaced some of the simple, solid hinge pins, I'd pass on the more complex ones.
To make the work easier, it's best to remove the buttstock. Of course, you must take off the barrel and forearm. On my gun, I also removed the spring-loaded ejector.
The next step is to remove the existing hinge pin. With my H&R, all it required was to place the receiver right side down on a metal bench block and drive out the pin. Generally, these solid pins are driven out from the left to the right. Be sure to use a flat-faced punch just a bit smaller in diameter than the hinge pin. If your punch is too large, you'll scar the side of the receiver. A few healthy hits with a hammer will normally drive out the pin.
Once the pin has been removed, the barrel is placed back in the receiver. You'll need to use clamps to help hold the barrel in place. I use a homemade clamp that is made of two pieces of all-thread rod, a couple of pieces of flat stock for cross pieces, and some nuts to secure the barrel. One of the cross pieces is placed on the muzzle side of the forearm lug on the barrel, and the other is placed behind the rear end of the receiver. The nuts are tightened up so the barrel is drawn back tight against the face of the receiver.
Another clamp--in this case a small "C" clamp--is used to press the barrel down into the receiver. It contacts the top of the barrel near the breech and the under side of the receiver ahead of the trigger guard. With these two clamps in place, the barrel is held firmly in place in the receiver.
Take a look through the hinge-pin hole in the receiver. You'll see the hinge-pin contact surface on the barrel as being slightly recessed. That's where we have a problem. We'll use a tapered pin for a replacement hinge pin.
Commercial taper pins are available in a variety of sizes. The ones most often used in a gunshop range from #5 to #8. The smallest diameter of the #5 pin is 0.243 inch, and the pin increases to 0.350 inch on the big end. As the number increases, the pin gets larger. These pins are matched to tapered reamers. Both reamers and pins are available from gunsmith and machine-tool-supply houses.
In selecting the correct reamer, first measure the diameter of the left-hand end of the old hinge pin. In the case of my H&R, it is 0.375 inch. I used a #8 reamer because it would completely clean up the inside of the hinge-pin hole.
With the shotgun secured in a padded vise, I applied cutting oil to the reamer and inserted it from the right side of the receiver. The reamer was turned clockwise and removed frequently to clear chips and reapply cutting oil. I visually checked the inside of the hole each time. I was looking for a single smooth surface f
rom the right side of the receiver to the left side. I also wanted the contact surface of the barrel lug to match the hole surface in the receiver. Once I had achieved a single smooth surface, I stopped cutting.
The hole was cleaned of all chips and cutting oil, and the replacement #8 taper pin was also cleaned with a degreaser. The #8 pin was then inserted into the receiver from the right side. Put the little end in first! The pin should extend all the way through the receiver with pin stock protruding from both sides.
Take a heavy hammer and drive in the pin until it's firmly seated. Remember, the only thing holding the pin in is friction, so you want a nice, tight, secure fit. While you don't want it to come out, you don't want to get so hammer happy you damage the receiver. A few sharp blows are all it normally takes.
Remove the clamps and check the barrel-to-receiver fit. There should be no side-to-side movement at all. As an added plus, any gap between the end of the barrel and the face of the receiver should be eliminated as well. If everything checks out, you can cut the ends of the pin flush with the receiver. If you are refinishing the receiver, you can polish the pins down for a perfect match with the receiver. If not, be darn careful you don't scratch the receiver as you file down the pin.
You should be aware that the taper pins are normally not hardened. Unless they're hardened, they'll eventually wear. However, unless your gun is subjected to an unusual amount of use, this new pin should last for many years. The original, which was fairly soft, lasted 50 years.
Replacing a hinge pin is an interesting project. And who knows, once you tighten up one of these old guns, you might convince someone that you're a magician!
Until next time, good luck and good gunsmithing!