by Tom Gaylord
Writing as B.B. Pelletier
The El Gamo David is a lower-powered breakbarrel from the 1960s or’ 70s.
This report covers:
- H&N Finale Match Heavy
- Breech seal
- Pick it out
- Seal is out
- What to do?
- Cocking effort
Today we look at the El Gamo David breakbarrel rifle’s velocity. In Part One I predicted that, if the powerplant is in good shape, the David should be able to push an 8-grain pellet out at between 550 and 600 f.p.s. I have not chronographed a single shot yet, so I will find this out as you do. Let’s get right to it.
H&N Finale Match Heavy
The first pellet I tested was the 8.18-grain H&N Finale Match Heavy wadcutter. The tin says they weigh 8.18 grains. I weighed five and got this:
Then I shot a string of 10. Before the string started I shot 2 pellets to “wake up” the powerplant. Then I shot the string and 10 pellets averaged 480 f.p.s. The low was 464 and the high was 487, so the spread was 23 f.p.s. That’s not a terrible spread for a springer, but I would always like to see it smaller. At the average velocity this pellet generated 4.2 foot-pounds. I had expected more like 5.5 foot-pounds.
That string was slower than I expected. But the powerplant sounded okay. What is the first thing you should look at when you discover that a breakbarrel is off its feed? I’d like to turn this into a quiz, but we really don’t have the time, so I’ll tell you. The first thing you look at is the breech seal. Let’s look now.
The David’s breech seal isn’t looking so good.
Everything you see that’s round in the photo above is the breech seal. It may look like an o-ring but it’s not.
Take a look at the picture. The David breech seal is not an o-ring. It’s much larger. That tipped me off that Gamo had used a formed proprietary breech seal. For the prospect of fixing the rifle quickly, that’s not good.
Pick it out
I used a dental pick to start the breech seal coming out. That puts holes in the material and even tears out chunks, so this side of the seal cannot be reused. It took about ten minutes to get the seal out far enough that its size could be seen. I had hoped to possibly substitute a Weihrauch breech seal, but once I saw the size of the David seal I knew that idea was out. The David seal is huge!
By the way, both ends of my dental pick were severely bent in the process of picking out the seal. The good news is the bent ends will break off and I will have a different sort of pick when they do.
It probably looks like the seal is ready to come out at this point. Not so! It took another 10 minutes of careful work with a small pocketknife blade to get it out.
Once the seal was out I confirmed that nothing I had on hand would replace it easily. I can think of many ways to repair the gun quickly at this point. Fitting a wood or metal spacer in the deep breech seal hole and topping it off with an o-ring seems possible. The spacer would resemble the original seal in size, but would be shorter so the o-ring that sat on top would seal the breech.
Or find a piece of rubber tubing that’s close to the same diameter as the breech seal, but a little smaller. Wrap it with Teflon tape to bring it to size. Cut it shorter than the breech seal so an o-ring can sit on top.
Or cut several leather washers and stack them in the hole. Either top them off with an o-ring or make them so high that they squash and become the breech seal themselves.
Once the David’s seal was out I could see the size. It’s huge! More like a section of thick tubing cut to length. We are looking at the bottom in this photo, showing that the seal cannot be reversed. It’s not smooth enough.
The breech seal hole is very deep. I measured it as 0.372-inches from top to bottom.
That seal hole is deep — 0.372-inches to the bottom! It needs to be cleaned.
What to do?
What to do next is another pop quiz question. If you’re a lover of these old-timey airguns you know what to do. Get on the T.W. Chambers website and look under El Gamo. Only there is no listing for EL Gamo. Okay, just Gamo then. There is a listing for that, but no David model is shown. But what do we know?
First, we know that the El Gamo Expo was popular around the same time as the David and it lasted a lot longer. We know that from comments left by readers Lain and GunFun1 to Part 1 of this report.
Second, we know that the Expo was roughly equivalent to the David — or at least we believe it was. We believe that the David was for a limited market and the Expo was for a broader market and most likely replaced the David when it came out.
Third we know that in manufacturing a company will always attempt to make one part work for many different models. That is especially true of parts that share a common purpose — like breech seals. If you have gone to the trouble of creating the tooling and fabrication processes for a proprietary seal, you want to do it as few times as possible.
That only makes sense, as each unique part not only needs to be manufactured, it also needs to be managed. The fewer unique parts you have to manage, the better. You can buy 100 o-rings for a dollar and call them breech seals or you can spend the time and labor making 100 unique seals. The fewer unique parts that are in your product, the easier it is to make — though the performance will be at the mercy of the generic part you select and you will also have to ensure a longtime supply of the generic part.
The drawing of the Expo shows a breech seal that’s shaped like this one. It’s worth a try!
I GUESSED that the breech seal for the Gamo Expo that TW Chambers does have in stock will also fit the David. The price was 5.25 British pounds, plus shipping. By the time it arrives in about two weeks I will have about $15 invested. If I’m wrong about the fit, I can explore the other less desirable options.
Well, I can’t shoot the rifle without a breech seal, so the velocity test has to be suspended. But I can test the cocking effort.
The David cocks with 15 pounds of effort. That makes it good for kids.
That’s where we find ourselves with the David. We are waiting on parts and we have a baseline on where the rifle was with the breech seal that was in it.
This is the downside of working on older air rifles. Sometimes they need attention. That’s just as much a part of the story of the El Gamo David as any of the other testing will be. As anyone who fools with vintage airguns will tell you — this is the fun part!