Methuselah - Part 1
Rebuilding a Markham BB gun
by B.B. Pelletier
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Vince rebuilt a Markham gun for Wacky Wayne, and here's the first part of that project. If you'd like to write a guest post for this blog, please email me.
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Methuselah--Rebuilding a Markham BB gun
Wayne is a trusting soul, no doubt about that. Doesn't know me from Adam, yet he starts sending me all sorts of stuff to work on, including a very old and somewhat rare Markham Model D BB gun dating from somewhere around the turn of the century.
Before I get into the gun itself, a little history on the Markham Model D is in order. But I don't know any, so I'll have to confine my remarks to pointing out that this gun seems to follow the standard turn-of-the-century methods of BB gun construction and operation.
I guess that by the 1890s termites had finally gotten the better of the all-wood BB guns, such as the Markham Chicago, and that mass-produced sheet-metal construction had become standard practice. The 1902 Sears catalogue boasts that sheet-metal guns have "no castings to break," so the cheap way of doing things was being passed off as the better way of doing things. Then, again, maybe castings were a real problem back then.
So, Wayne buys this thing on gunbroker.com and has it shipped directly to my house. Now, I've not seen or handled a genuine vintage BB gun before, so I really didn't know what to expect. In my mind is the whole mythical idea that back in yonder years they made REAL BB guns, not the plastic-y toys you get today. And because they'd not been soiled by the cheap, imported competition and the liability-minded bean counters of modern times, these old BB guns must have been something else.
It was with considerable anticipation that I awaited the arrival of the Markham. When it does show up, the first thing I noticed was that the small box felt empty. At first, I thought the seller had forgotten to put the gun IN the box, but no, it was in there all right--all 1-1/2 lbs. and 31 inches of it. Immediately I'm clued in that this is not at all what I expected. All my presuppositions about the Markham got tossed out the window.
Cosmetically, it's so-so. The metal parts are all nickle-plated, and it's deteriorated to the point where it's maybe 60-70%. The wood is actually pretty good. Almost immediately, I tried to evaluate its operational condition, which means oiling and shooting. It's supposed to shoot real lead BBs. The original lead BB was shotgun shot--0.180" in diameter. So, the modern steel shot (0.173") is a bit too small. The Markham is a muzzleloader, and I was worried about the possibility of a steel BB falling right through whatever was supposed to catch and hold the lead BB and that it might end up rattling around inside the action. I muzzleloaded a .177 pellet, and the gun pops it out at about 135 fps.
Not all that bad, really, and I know that Wayne wanted to make a conversation piece/shooter. I figured that was quite enough, knowing that it would go even faster with modern steel shot because, even though they're quite a bit smaller, they weigh only 5.1 grains compared to over 9 grains for old-style lead BBs. I also got the bright idea of installing a modern shot tube into it. That way he could use steel shot without a problem because a modern shot tube would be properly sized. If we're gonna put a new shot tube in it, why not a 499 competition shot tube? They're only $12, and a match-grade 100 year-old Markham would be a hoot. I ordered a couple to see what I could do.
After a couple of days, I tried the Markham again and found that the velocity had dropped drastically. There's some black gunk spitting into the barrel. Fearing the worst (almost), I decided that the powerplant had to come apart.
Even though I suspect I'm the first one in there in 100 years, getting it apart wasn't that bad once I figured it out. Turns out all you have to do is pull out the trigger screw and slide a sleeve to the rear, which relieves the spring pressure. That sleeve didn't want to move at first, but I coaxed it out without damaging the gun. After that, the rest of the Markham came apart easily.
The Markham Model D disassembled.
A couple of side notes. There's only one casting in this rifle--the trigger, and it's pretty ugly! Maybe sheet metal construction for the rest of the gun wasn't such a bad idea. I'm guessing that mass-production spot welding had yet to be perfected since the Markham is actually soldered together! Not sure what solder formulation they used, but it had to be a time-consuming process.
Once I got to the innards, I immediately looked at the piston seal. The piston is made from a piece of square tubing with a steel disk attached to the front of it. The seal (a simple leather disk) is pinned to that metal disk with a copper rivet. The leather seal was disintegrating just as I thought, but it turned out there was a bigger problem to deal with.
The piston assembly was supposed to be held together by two ears that came through the back of the disk and were bent over, but one of the ears was broken.
Top: The end of the piston showed only one side was intact...the other had broken off. Bottom: The metal disk that fits over the end of the piston isn't securely held in place due to the aforementioned break.
This is a structurally critical part, as the mainspring bears against the disk, not against the piston. But the trigger and cocking link act on the piston, so when the gun is cocked those ears have to hold the pressure of the compressed spring. If both those ears broke, the disk would slam forward while the piston stayed behind.
After much soul-searching (after all, I had a real reluctance to do ANYTHING to the original parts), Wayne, BB and I concluded that it would be OK to bronze-braze repair the piston/disk assembly. I thought about trying to reuse the rivet (or getting a new one), but it occurred to me that in another 100 years or so Wayne's great-grandson might be asking my great-grandson to put a new seal in this thing. I wanted to make it easier for him, so I decided to use a No. 6 machine screw, a filed-down nut (so that it would fit inside the piston) and a countersunk washer. Of course, the screw would be trimmed down in length and secured with a threadlocker once it was time for final assembly.
This picture shows the repaired part along with a new leather seal, the old copper factory rivet that held the seal in place and the parts I was going to use to secure a new seal (more on that later).
First, I had to make a new seal. The one in the above picture turned out to be a smidgen too small, so a cheap leather belt from Walmart volunteered, and I made my first-ever-from-scratch leather piston seal.
I cut the seal a bit oversized and trimmed it down until I got a nice, snug fit in the tube. I put it all back together.
The leather seal assembly topped off the repaired piston.
Now I had another problem. There's a leather plug that forms the end of the compression tube. While it hadn't deteriorated as badly as the piston seal, it was obviously on its way out. The plug is made from three leather disks with a tapered brass transfer port sandwiched in there, so I'm back to making more leather disks. Turns out that an almost perfectly sized punch could be made from a piece of 3/4" copper water pipe, but copper is hardly the best punch material around. If Wayne starts sending me Markhams in bulk, I'm gonna make one out of steel.
I made 3 new leather plugs for the end of the compression tube.
It turns out that the brass piece between the second and third disks is what catches the BB. The hole on the small end is about 1/8-inch, so steel BB shot won't fall through. The breech end of the shot tube fits snuggly into the hole. When a BB is dropped into the barrel, it falls into this plug and wedges itself into that transfer port. It does a fair job of holding it, and a loaded BB will not fall out even if the gun is pointed straight down.
I assembled the new plug and bound it together with a couple pieces of thin bailing wire
Bailing wire holds the 3 leather pieces snugly, along with the brass piece sandwiched between them.
When I installed the plug into the gun (it goes in from the rear), I first dropped in a steel washer so the front of the plug had plenty of surface to bear on and was not pressed up against the end of the barrel shroud.
The v-shaped transfer port holds the BB so it doesn't fall into the compression tube or roll out...even if the barrel is pointed downward.
Like the rest of the parts in this gun, the piston was not exactly "precision machined." However, the rear portion of the cutout was reinforced with some extra steel. The years haven't been kind to the cocking slot. It took quite a beating over the past 100 years and looks a bit longer than the factory intended.
No precision machining on this piston, but it did have some reinforcement.
The cocking slot was chewed away over the past 100 years, making it a bit longer than when new.
The cocking slot lengthened as the cocking link pulled the piston back against the mainspring. Since that spring is undoubtedly softer than it was when the gun was new, I expect that the slot isn't gonna wear much more. The link was getting jammed in that slot extension, so I opened it up a bit with a small rotary file.
The spring that came out of this gun is old, so I figured it might be wise to replace it. And since the gun was going to be used, I wanted to install a softer spring that might put a little less stress on the rest of the parts. I tried a common hardware store spring.
The longer spring is the new one. I had to cut about 3" from it to get it to fit...yet it wouldn't be used.
The old spring didn't appear to be broken. I think the spring ends "as cut" from coil stock and not flattened look exactly as they did when the factory put this thing together, although I imagine the spring was longer and straighter! Unfortunately, the new spring produced such low velocity--about 125 fps with steel BBs--that I didn't end up using it. The original went back in, but in its weakened condition I believe it'll still be relatively gentle on the rest of the action.
As I mentioned earlier, the only piece of cast iron I've noted in the whole gun is the trigger, and it doesn't speak well for Markham's iron casting techniques. The trigger spring is also pretty beat and will be replaced, but the trigger pin looks fine.
The sear at the front of the trigger didn't look bad at all, so I suspect the metalurgy of the casting is better than the aesthetics. I didn't work the sear angle in the hopes of getting a sub-1-lb. competition trigger out of it!
About the only other thing I did was replace the rear cocking pin/screw, which was bent, with a new one. It's shinier than the rest of the gun. If Wayne doesn't like it, he can put the original back in!
With the Markham back together, it's doing about 170 fps with steel BBs. I actually tried a 5-shot group at about 16' and got a group just about 1.25" (rested). I thought that was pretty doggone good with no rear sight (it had broken off) and with the lead BB barrel still in place. By comparison, that's less than half the group size BB got from a new Mendoza BB gun he tested a couple years ago.
Anyway, the remaining tasks are to install some sort of rear sight (the original had broken off) and adapt the Daisy barrel. Since the barrel hadn't arrived yet, I decided to start playing with the sight first to get some idea how much rear elevation it would need and how difficult it would be to fashion something. You'll have to wait for part 2 to find out how that and the rest of the project turned out.