Posts Tagged ‘double-set trigger’
by Tom Gaylord, a.k.a. B.B. Pelletier
It’s been a while since I wrote about this gun, I know. Airgunner Larry Hannusch told me how to disassemble it, and I started…only to stop when I encountered a barrier. I’ve resolved that barrier, and today I’ll show you the inside of my gun to the extent that I’ve disassembled it.
Larry told me to remove the screws on top and beneath the action that were obvious, then separate the two parts — action and stock. I removed 4 screws, and the action came loose from the stock a little bit. Then, it stopped cold. That was where I stopped working and set the gun aside. Yesterday, I picked it up and began from that point.
A bugelspanner (actually, correctly spelled buegelspanner or bügelspanner since the u has two dots — called an umlaut — over it) translates to a triggerguard-cocker. The triggerguard is pulled down to retract the piston and set the sear for firing.
Triggerguard is up in the shooting position.
The triggerguard lever is fastened to a pivoting axle bolt located in the back of the stock. The bolt shows in the photos above. Since this lever is connected to a linkage that’s connected to the back of a piston held under tension by powerful mainsprings, it made sense to me that it had to be disconnected from the piston for the stock to separate.
I removed the bolt that screws into a very long bushing inset into the opposite side of the butt. Then that bushing was tapped out the other side of the stock. But the cocking lever wasn’t quite free. At the top of the triggerguard lever, the cocking linkage passes through the lever and is prevented from coming free by a small screw that passes through one end of the linkage. I have arranged the two parts and their screw below for you to examine.
The triggerguard and cocking linkage, arranged as they are in the gun — I think! Until I assemble the gun, again, I won’t be sure of the correct orientation of the cocking link.
That tiny handmade screw goes through the hole in the cocking link and prevents it from slipping through the triggerguard when the gun is cocked. Notice that it has two smooth bearing surfaces — one on either side. As the gun is cocked, the cocking link moves up and down in the cocking slot that’s in back of the triggerguard. It’s a moving fulcrum.
This is the triggerguard lever pivot bushing and screw on which the lever pivots when during cocking. Note the smooth band around the base of the bushing. We may assume that’s where the pivoting happens.
The screw and pivot bushing have been removed from the stock.
The entire underside of the stock is open, allowing room for the cocking linkage to move.
When I removed the cocking link from the back of the piston rod, I found the screw that attached the link to the piston rod was sheared in two, plus the rest of the screw was very mangled from pressure and work. Clearly, this part is too soft and also overworked.
The screw that holds the cocking link to the rear of the piston rod is mangled and galled from too much strain. The threaded portion remains in the back of the piston rod and needs to be removed. This part may need to become a roller bearing.
The first part to come off the gun was actually the top action plate that also holds the rear sight. It is the anchor plate for 2 long screws and one short one that holds the action together. Once they were out, the plate didn’t come off without a lot of wiggling and some prying.
Three screws, and the top plate came off with the rear sight attached.
This is where the top plate came from.
The gun is now partially disassembled. The double-set trigger mechanism is exposed and can be disassembled and cleaned, but the piston is still under compression inside the compression chamber that hasn’t yet been separated from the barrel. To see the piston and mainsprings, The backplate that the piston rod passes through has to be drifed down out of its dovetail
The double set trigger assembly is now exposed for cleaning and possible disassembly. To remove it from the gun, it’s tapped down, freeing its front dovetail.
The double-set trigger assembly must now be removed downward from the cylinder dovetail, freeing the trigger plate and back plate from the cylinder and relieving tension on the mainsprings.
I found the number 80 on many of the larger, unique frame parts. I believe that’s either a serial number or an assembly number to keep all the parts together because this gun shows a lot of handmade parts and hand-fitting.
When I open the barrel, I see some dark particles that I believe are small chunks of leather that have broken off the piston seal, so it may be deteriorating. And I need to look at the condition of the mainsprings, plus probably lubricate them just a little.
The bottom plate on which the double-set trigger sits is dovetailed into the frame (the rear of the compression/spring tube). It has to be pushed straight down to relieve tension on the mainsprings, and I do this with by tapping with a rubber hammer. The plate comes out of the dovetail easily enough; but the double volute mainsprings are under considerable tension even at rest, and the trigger plate and separate backplate fly off the gun along with the volute springs.
The trigger plate has a dovetail at its front that grabs the rear of the cylinder and holds the powerplant together. The cylinder back plate (left in the photo) is held between the 2 parts. The black part that’s flopping down on the back plate is the sear.
The piston can now be withdrawn, and I can see that the leather seal has, indeed, deteriorated. The part that comes in contact with the air transfer port is damaged from repeated impacts. I think I’ve found the reason the gun fired so roughly.
Bugelspanner piston at the top is much fatter than the Beeman R1 gas-spring piston unit below, but the stroke is also shorter. The notch in the bugelspanner piston rod is the cocking notch.
The leather piston seal has deteriorated. It looks okay, but it’s crumbling and flaking off. This is why the gun fires so harshly.
Double volute springs attached to a central guide for the mainsprings of the bugelspanner. They’re in good condition but very dirty and dry.
The double-set trigger has a weak front trigger leaf spring, which accounts for it not setting well and firing too easily. That will also have to be corrected.
The inside of the compression chamber is filthy, but it doesn’t seem to be damaged. A good cleaning is all it needs.
For many of you, looking inside this airgun is probably like looking at the dark side of the moon. So many of the parts appear foreign to your eyes. All that has really changed over the years, though, is how the parts are designed. They work in the conventional way that modern spring-piston parts work, so they must be corrected in the same way that a modern spring-piston powerplant would need to be.
There are numerous major repair jobs that must be undertaken before this airgun will shoot again. There’s certainly lots of cleaning, which is followed by careful lubrication of many of the parts.
Some new parts have to be fabricated, as well. That will not be an easy task, but it’s worth the effort. I know you were hoping to see a test real soon, but that’s not going to happen. I have to feel my way around this gun carefully; because if every job isn’t done right, the gun won’t work when it goes back together. I’ll go about the work methodically and take some pictures as I go, but I probably won’t report on the gun again until all the work is completed.
by Tom Gaylord, a.k.a. B.B. Pelletier
Today, I have a story for you. A couple weeks ago, one of our blog readers — a man named Eric — emailed me a link to a local craigslist.com posting. Eric met me at a gun show last year, and I sold him a Winchester model 427 (Diana 27) air rifle. He already knew about fine vintage airguns, and the 27 had been on his wish list for a while, but I don’t think he was a blog reader. Well, we fixed that right away! Since then, he’s been reading the blog and becoming more familiar with his new rifle and airguns in general
The listing he sent me showed a Tyrolean air rifle with the traditional high-cupped cheekpiece and hooked buttplate. What was even more fascinating were the double-set triggers and the large aperture sight located at the rear of the receiver, as well as the sporting sight mounted on the barrel.
The gun was a bügelspanner, or loosely translated, a triggerguard (lever) cocker. I’ve owned 2 bügelspanners in the past, but neither was as nice as this one. And the funny thing is that this was posted on craigslist! That’s funny because guns are sold on gun websites — not on a general website like craigslist.
But this posting had lasted for a minimum of 2 weeks before I saw it. So, I contacted the seller and, glory be, he still had it! We met last Sunday, did the transaction and this was one of those rare times when the gun was exactly as represented.
The gun is a smoothbore .25-caliber gun. The seller, named Joe, told me he had owned it for the past 34 years and had gotten it at the age of 8 as a gift from his father. The gun is much older — probably dating back to around the 1920s or ’30s.
It’s a spring-piston gun that has 2 opposed volute springs that compress against each other. They push a leather-covered piston in the same way that a coiled steel mainspring does in a conventional spring-piston gun, so this is just an odd form of spring-piston airgun.
Two volute springs push against each other when compressed.
The volute spring is a flat spring that’s been coiled and stretched into this shape.
I was attracted to this airgun because of a long, abiding interest in zummerstutzens — indoor gallery or parlor guns used for target shooting. I’ve been fascinated with them since I was a teenager and first read about them in Guns & Ammo back in the early 1960s.
The zimmerstutzen rifle is usually found in the Tyrolean style, but not always. It’s nominally 4mm, but there are more than 20 specific calibers for which the guns were bored. They fire either fixed ammunition (a cartridge) or separate ammo with a percussion cap and round lead ball loaded separately. Rather than get into the full description here, I invite you to read my full article about them. I normally don’t like giving homework assignments; but if you read that article and look at all the pictures, you’ll have a much better understanding of the gun we’re examining today.
The subject gun
I was inclined to believe the subject gun is a dart gun, but what little historical documentation there is mentions using pellets as well. I thought it was a dart gun because it’s set up for extreme accuracy, and I didn’t think that pellets could be that accurate in a smoothbore barrel. But we did do a test of the Diana 25 smoothbore at 10 meters and established that it is, in fact, very accurate at that distance. So, I really don’t know if I’m supposed to shoot darts or pellets in this gun. For the present, I only have pellets because .25-caliber darts are not that common. But I could certainly make some.
This type of gun either fits or doesn’t fit — there’s no in-between. I’m lucky that it fits me pretty well. But that sporting rear sight does get in the way of seeing the front sight. I would have to remove it to use the rear sight.
Why a sporting rear sight? Shooters in the US are not familiar with how European airgunners view target shooting. They use their guns for both precision target shooting and also for sporting use. I guess the best comparison would be to the Hunter Class of field target. Therefore, European target guns often have both a precision rear peep site and a second sporting rear sight located somewhere on the barrel. The subject gun has both.
The front sight is a fine post and bead, which is typical of all zimmerstutzens and, indeed, of many target guns from the 19th century. This sight is very fragile, so it’s protected by steel “ears” on both sides.
The sporting rear sight is adjusted in both directions by a clock key.
Rear peep sight is also adjust by a clock key and can be removed to use the sporting sight, only.
Front post-and-bead sight is delicate, so two steel ears protect it.
The gun has an octagonal barrel, which dates its manufacture to before World War II. It’s impossible to get a more precise date than that because these guns were made from the beginning of the 20th century until the early 1950s. The octagonal barrel also suggests a time before 1940. Most likely this gun was made in the 1920s or 30s, but I have no way of proving that.
The name Original is engraved on the barrel. Several sources say that this is a name used by Oskar Will in Zella Mehlis, Germany; but one source says that name, by itself, was used only by his competitors, and all of his guns also have the word Will on them, as in Original Will.
The name Original may mean this gun was made by Oskar Will of Zella Mehlis.
The gun is cocked by pressing down on the triggerguard, which is actually a long lever pivoted near the bottom rear of the butt. You can see the pivot pin sticking through the rear of the buttstock. A linkage pulls the piston back, compressing the two springs. To load the gun, you press a catch forward on the right side of the forearm, and the rear of the barrel can then be tipped up. You could call this a breakbarrel, but the barrel doesn’t have anything to do with cocking the springs. In that respect, the gun is like the breakbarrel Whiscombe rifles.
The cocking effort is pretty demanding. It’s on the order of 40 lbs., at least. I can’t see how a boy of 8 was able to cock this gun, but maybe his father cocked it for him until he grew into it.
Triggerguard is shown up…in the firing position.
Triggerguard is pulled down to cock the springs.
Push the catch forward, and the barrel can be tipped up for loading.
The double-set triggers on this gun are interesting. They work in the normal way — the rear trigger is pulled to set the front trigger and the front trigger fires the gun. However, there’s one difference. Many guns with double-set triggers will also fire when the front trigger is pulled without being set. This gun will not. If the trigger is not set, the gun cannot be fired.
Double-set triggers function normally, except the gun won’t fire unless the trigger is set. Many double-set triggers will fire when the front trigger hasn’t been set, but not this one.
Joe told me he shot the gun, so I figured it would be okay for me to do, too. First I dumped about 20 drops of 3-In-One oil down the air transfer port and gave it an hour to soak into the leather piston seal. The, I loaded an obsolete 20-grain Diana Magnum pellet and shot it into the trap from just a few feet away. The firing cycle was very harsh, so I won’t be doing that, again, until I can examine the condition of the powerplant. I could hear how slow the pellet moved, which leads me to suspect I’m right about this being a dart gun.
The gun is stocked with a light-colored walnut that’s checkered on the straight pistol grip. Also typical of the Tyrolean stock is the thumbrest that protrudes from the right side of the grip. That makes this a definite right-hand rifle!
This top view shows how thick the buttstock blank had to be to begin with!
The gun’s metal is finished with a combination of heavy nickel plate and hot-tank bluing. I would put the finish at 80-85 percent, which is to say…a lot! There are pepper tracks of rust scattered around the blued barrel, but an application of Ballistol and steel wool has begun to remove them. I’ll keep this up for as long as it takes to get down to smooth metal.
This report will not follow the traditional pattern of velocity testing followed by accuracy testing. For starters, I think the gun is too fragile to shoot that much, plus it does fire harshly. I need to find out what’s going on inside before I do much of anything.
I made this Part 1 so I could come back to it with a second report, though I have no plans for that right now. But as I learn more about it, there will be enough information to make an interesting Part 2.
by Tom Gaylord, a.k.a. B.B. Pelletier
Adam Vierra is this week’s Big Shot of the Week on Pyramyd Air’s facebook page.
I wasn’t sure there was going to be a Part 3 to this report. But yesterday, when I read your interest about the airguns with double-set triggers, I decided that it was okay to do one more, and this one will be about set triggers, match triggers and stuff like that.
As it happens, this blog is very timely for me, because this past Wednesday I was at the range shooting several firearms and a new airgun that you’re going to read about in January. One of the firearms I shot was my new Winchester high wall in .219 Zipper Improved. Some of you may remember that was the rifle I recently bought and discovered after the fact that it has a single-set trigger.
The screw that hangs down behind this trigger is the telltale clue that it’s a single-set trigger. You can either pull it the usual way, in which case it breaks at about 3-1/2 lbs., or push the trigger forward after the rifle is cocked. It then breaks at just 6 oz.
Shooting an obsolete caliber like a .219 Zipper Improved is a lot of work because they don’t make ammunition for it. In fact, they never have. This cartridge is called a wildcat because it’s always been necessary for the shooter to make the ammunition from some other cartridge. The .219 Zipper was a standard commercial cartridge at one time and is based on a 30-30 case. The Zipper Improved is based on the standard Zipper case, which means it, too, can be made from a 30-30 case. In fact, that’s how they’re made today.
Here we see a 30-30 (left) and the .219 Zipper Improved that sprang from it.
But my shooting buddy, Otho, discovered that the case dimensions of the now-obsolete but far more recent .225 Winchester are virtually identical to the .219 Zipper Improved. The rim is thinner and a trifle narrower, but it’s close. So, he thought we could make our cases from .225 Winchester cases, which are now being produced in limited quantities.
To make a long story short, the .225 case is so exact that all I have to do is prime it, fill it with powder and put a bullet in the neck. That saves me about 5 minutes of case preparation time for each case (when making them from a 30-30), and I also don’t have to clean my gun after fire-forming the new cases, which is a royal pain. Also, I lose about 40 percent of the formed cases, and I don’t think I’m going to lose any with this new method.
On Wednesday, I was at the range with 20 rounds of .219 Zipper Improved made from new .225 Winchester cases to see if this works. The measurements said it should, but since we’re generating 45,000 psi with every shot, theory and practical application are two different things.
I loaded the cartridges on the light side for safety, and I loaded only 5 with each amount of powder so I wouldn’t have to pull apart dozens of cartridges if they weren’t right. I’d seated the 40-grain bullet out as far as I felt I could and still keep it stable in the case. That’s supposed to improve accuracy — if the bullet doesn’t travel far before engaging the rifling.
The set trigger
Now we come to the subject of this report. My rifle has an aftermarket single-set trigger that releases with 6 oz. of pressure. To me, it feels like nothing. I can barely feel my finger touch the trigger blade when the gun fires. That’s as light as I ever want a trigger to be, and only then if it’s on a target rifle or a varmint rifle like this one. I want to be in position and ready to take the shot before I touch that blade.
So, now you appreciate that everything was perfect for this endeavor. If the loads I cooked up were accurate, nothing should get in the way of the results. Put the crosshairs in the center of the aim point at 100 yards, get stable and touch the trigger — BAM! The deed is done. All you have to do is look through the scope. The bullet should be moving at about 3,600 f.p.s., so the hold isn’t very much of a factor. Just make sure you have your head at the same spot every time so parallax cannot enter into the equation, and you should be good to go.
The first 5 shots included the very first shot after the barrel had been cleaned. That one went almost an inch wide, while the next 4 shots landed in a group that measures 0.51 inches between the centers of the two widest shots.
The rifle was shooting a little high so I adjusted the scope down for the next group.
The next 5 shots were with a powder charge weighing one grain more than the first load. I saw the first bullet from this batch land almost exactly on the vertical line above the center of the aim point, so I proceeded to shoot 4 more shots after it. I couldn’t see these shots through my 10x rifle scope, but the spotting scope revealed a tight cluster next to the first shot. That was worth investigating. We called a cease fire, and I walked down to look at the target. What I saw was amazing. The final 4 shots had landed in a tiny cluster measuring 0.239 inches between center. When the first shot is added, the group opens to 0.444 inches. For me this is a very good group!
Top group is the first 5 shots with the new cases. Bottom group is the second 5 shots, using one grain more powder. The group measures 0.444 inches between centers…and the smaller group of 4 measures 0.239 inches, which is less than a quarter-inch at 100 yards.
But the single thing that made this group possible — other than lucking out and picking the right bullet and the absolute best powder charge on the first time out with these new cartridges (which is at least a thousand-to-one-guess) — was the set trigger. It took me out of the equation, by virtue of making the rifle fire when all things were perfect. Even a heartbeat, which can throw off a bullet by more than an inch at 100 yards, was not an issue because I was using the M-T-M Predator shooting rest that holds the rifle perfectly on target without my help.
And that’s what set triggers do. They allow you to either eliminate the human from the shooting equation; or, conversely, they allow the human to knowingly pull the trigger at the exact instant the sight picture is perfect. That’s called sniping the target, and it’s usually not recommended; but since a set trigger doesn’t move the gun like a standard trigger does when it’s pulled, you get away with it.
So far, I’ve mentioned only the single-set trigger. The double-set trigger is more common and works just as well, if not better. Perhaps the most familiar place to see this kind of trigger is on a muzzleloading rifle, where they were favored over the plain trigger.
Double-set triggers often work like normal triggers if they’re not set. Usually, the rear trigger is pulled to set the front one, though not always. The double-set was very popular on bellows dart rifles in the 1700s and 1800s, and these are the triggers that are famous for being so sensitive that a breath of air can make them fire. I’ve owned several rifles with double-set triggers, including a five-lever trigger made by Aydt that was extremely sensitive. But I’ve never experienced a trigger so light that air, alone, can set it off.
Pull the rear trigger to set the front trigger. The rifle can also be fired by just pulling the front trigger, though the pull will be heavier.
Set triggers and target rifles
Set triggers were once an important part of all target rifles. From the days of chunk shooting, when the rifle was a Kentucky long rifle rested on a log (called a chunk), to the final days of international match shooting at 1,000 yards, the set trigger was as common as the vernier peep sight and spirit level front sight that eliminated cant.
In the sporting world, set triggers were found on many varmint rifles of the past. The double-set was more common than the single-set, but either one can be a blessing when you’re trying to do precise work. In recent years, set triggers have been making a comeback on many factory guns, but they may not be as necessary as they once were due to innovations in replacement sporting triggers. More on that in a moment, but let’s now take a look at set triggers on airguns.
For some reason, set triggers have not been very popular in airgun target shooting. Perhaps this started as a safety rule; but considering the light match rifle triggers now in production, that cannot be the only reason. The fact that set triggers do exist on target air rifles indicates that some people wanted to try them at one time, but the rules were written to exclude them from competition…just like Tyrolean stocks and tube rear sights…and today they’re seen only on vintage guns.
Here’s a prediction: If an airgun manufacturer were to put a nice set trigger in an accurate low- to mid-powered .177-caliber air rifle today, they would have a hit on their hands!
Non-set triggers that are still remarkable
This is for our blog reader GenghisJan, who asked blog reader Kevin how he would compare a set trigger to a match trigger. I believe the big difference is that you must intentionally set the set trigger for it to be light. If you don’t set it, the trigger-pull seems about normal. But a match trigger releases at just one weight, and it’s always light. How many times have I seen people fire a match gun before they were ready, simply because they were unaccustomed to how light the trigger is? It actually takes some learning to operate a match trigger safely, and some people never get it.
A Benjamin Marauder trigger can be adjusted to have a two-stage release where the second stage is light, but also positive. It’s more than the few grams of pressure that a true match trigger needs, but far lighter than most sporting triggers. This is a wonderful compromise in a trigger, to my way of thinking.
In the world of sporting guns, triggers have continued to improve until it’s possible to buy drop-in units today, or sometimes the parts to make a factory trigger as light as a set trigger. There are many manufacturers doing this — companies like Jewell Trigger, which makes sporting triggers that break at mere ounces. They’re a sort of set trigger that’s always set!
But in airguns, the choices are fewer. In the world of spring guns, there’s the Rekord that can be adjusted to release at just ounces of pressure if properly set up, and the Air Arms trigger that’s even more adjustable. There used to be some aftermarket triggers from companies that would drop in certain guns and be even lighter and better than Rekords, but they’re gone from the marketplace.
You’ll find more good triggers in the PCP world because they don’t have to restrain hundreds of pounds of force. And the state-of-the-art 10-meter match rifle trigger is at the top of the heap. With triggers this sensitive, you don’t touch them until you’re safely on target.
What’s it going to be?
I like a set trigger in the right circumstances. And since most of them can be fired without setting, I found them to be ideal for everything. But I’m just starting to experiment with the crop of new and improved replacement triggers that have hit the market. Though they’re less flexible than set triggers, they might be a good modern alternative.
As far as a true target trigger is concerned, the only place for that is on the range. And you have to train with it by dry-firing so you are ready when the time comes.