Marlin Model 1897 Disassembly

Marlin Model 1897 Disassembly
by
Gary Thomann
Thomann Engineering
Singletrack Publishing
Marlin Model 1897 Disassembly
Introduction
This is a manual for taking apart a Marlin model 1897 22 caliber rifle. It is primarily intended for
someone taking apart the rifle for the first time, when it is probably dirty and most of the screw threads
are stuck. Of course it can also be used for disassembling a clean rifle. The instructions also apply to
other old rifles because some time will be spent on how to remove stuck screws. There is another
manual available on the internet for about eight dollars that is advertised to be for the 1897. However,
it is actually for the Marlin 39A and there are several differences between the 1897 and the later version
of the rifle. This manual is specifically for the 1897. There are a few recommended tools and supplies
needed so let’s list those next
Tools and Supplies
Patience. This is not a one night project. There will probably be a lot of stuck screws that take several
days to get the loose. Don’t rush!
Assortment of hex screwdriver bits or some screwdrivers. The hex bits are best, try to find hollow
ground ones. These will be used to make screwdrivers to fit the rifle. If you are like me you probably
already have a bunch of these around.
Gunsmith screwdrivers. Actually not needed but if some of them have thin tips they could be handy.
The Marlin 1897 has very thin slots in the screws.
Bench grinder. The grinder will be used to grind the bits to the shape desired. Some other type of
grinding device could also be used.
Liquid Wrench, acetone/ATF 50/50 mix, wax. Some other fluid for loosening stuck bolts could also be
used. My experience is that the 50/50 mix of acetone and automatic transmission fluid is best.
Old drill press chuck. I used this to hold the hex bits and make a screwdriver. You could also use any
hex holder. I like the chuck because there is no slop when turning.
Mineral spirits. Optional, but I did use mineral spirits for cleaning the magazine tube. For other parts I
prefer using dish soap and water.
Dish soap and water. Check with your husband, he will know where to find the dish soap.
Small brass brush, old tooth brush, tooth picks, Q-tips, cotton rags.
Jewelers screwdriver. For cleaning out screw heads. Similar small instrument can be used.
Heat gun. Like used for shrink tubing.
1
Marlin Model 1897
Screw Threads
As I took apart the example rifle I tried to determine what threads were on each screw in case it had to
be replaced. This was not a particularly successful endeavor. At the present time the United States is
under the Unified Thread Form/Unified Inch Thread also referred to as ANSI/ASME B1.1-2003 and by
the term UN. The thread flank angle is 60. Normally this standard is just referred to as UNC (coarse)
and UNF (fine) and apparently an 8-UN that I not familiar with. There are two modified UN threads
named UNR (rolled) and UNJ (aerospace). There is an equivalent standard to UN for metric screws. If
you are going to replace a screw in the rifle one of the UNF screws would probably be used.
First let us note that Marlin was founded in 1863 by John Mahlon Marlin. The company made pistols
until 1875 and then began production of Ballard rifles. The first lever action rifle was made in 1881.
The Model 1897 was an improvement of the Model 1892 which itself was an improvement on the Model
1891. So, the screws that were used in the Model 1897 must have been developed based on
manufacturing from about 1863 to 1897, although there was probably a tendency to use the same
screws in the Model 1897 as had been used in the Models 1891 and 1892.
Before the 1840’s there was apparently little standardization in machine screw sizes and threads. In
1841 Sir Joseph Whitworth proposed a thread with a 55 thread flank angle and rounded roots and
crests. The Whitworth system did not seem to have small sizes, although of course somebody could
use his form with small screws. The standard Whitworth small screws are 1/16 – 60, 0.10-48, 1/8 – 40,
3/32 – 48. The terms BSW (coarse threads) and BSF (fine) are used for Whitworth screws. The
standard is obsolete but BSW and BSF screws are still used, particularly in Britian.
Standardization in the U.S. began back in 1861 with the specification of the Franklin
Institute/Sellers/United States thread. This standard was mandatory only for the military and
government departments. The Sellers thread had a 60 degree angle and had flat roots and crests.
Apparently the use of the Sellers thread was widespread by 1880.
In 1907 ASME defined two series that used Sellers thread and numbered the sizes by gage from 1 to
30. Each gage increase was 0.013 inch. Next came the American National Standard Screw Thread by
the Bureau of Standards, also referred to as CS24-30. It became effective July 1, 1930. After that
came the B1.1 standard adopted in 1949. It has been updated several times. Obviously the
standardization discussed in this paragraph was too late for the Marlin Model 1897.
So what was Marlin using? I would guess the Sellers thread. In the screws on the Model 1897 it is the
pitch (threads per inch) that don’t seem to match the modern screws. The diameter was less of a
problem. My rifle had all fine threads, the modern UNF screw threads are shown in Table 1. The
screws in the table are what we would like to use if we had to replace a screw in the rifle. As we will
see substitution doesn’t always work. The diameter shown in the table is the major diameter, the value
at the outside of the threads. The diameters shown in the table are actually maximum values. A more
complete thread table is shown in Appendix A.
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Marlin Model 1897
Table 1. Modern standard UNF screw sizes and major diameter.
Size
Dia, in
0 - 80 UNF
0.060
1 - 72 UNF
0.073
2 - 64 UNF
0.068
3 - 56 UNF
0.099
4 - 48 UNF
0.112
5 - 44 UNF
0.125
6 - 40 UNF
0.138
8 - 36 UNF
0.164
10 - 32 UNF
0.190
12 - 28 UNF
0.216
1/4" - 28 UNF
0.250
Getting Stuck Screws Loose
When I began to take my 1897 apart I found that about two-thirds of the screws were stuck. I have a
set of the eight Grace gunsmith screwdrivers. The next thing I found was that they would not fit the rifle
screws, the slots were much too narrow. I took a couple cheap screwdrivers and ground the blade
narrower on a bench grinder. Gunsmith screwdrivers are supposedly hollow ground. The Grace ones
were actually flat ground. I tried to grind mine in a flat profile also. I then tried some intermediate
pressure on the stuck screws, but they did not budge. I did not want to put any hard pressure on the
screws; I was afraid the bit would slip. Some of the screw heads were already damaged. At that point I
slopped some Liquid Wrench on the screws and retreated to the internet to find the best way to loosen
stuck screws.
The classic method to loosen a rusted bolt is to heat it red hot with a torch. While this is ok on a car
muffler it was certainly not something I was going to do on a fine rifle I paid $600 for. I was willing to
apply a bit of heat using a gun I have for shrinking tubing. I looked for reviews on the best solvent to
use. Apparently before they had Liquid Wrench and its siblings wax was used. That was interesting.
Then I ran across a review that claimed the best solvent was a 50/50 mixture of acetone and automatic
transmission fluid.
In the meantime I was giving some thought to the screwdrivers. I decided that using the quarter inch
hex bits would be the best. I already had a large collection of them in a tupperware container. Some of
them were even hollow ground, although the blades were too thick. I did some grinding on the flat side
of the wheel and tried the screws again. I needed something solid to hold the bits that had a handle
diameter that fit my hand well. I decided on an old drill chuck I had. Figure 1 shows the chuck and
some of the bits I eventually made. The photo also shows the two cheap screwdrivers I initially ground
down.
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Marlin Model 1897
Figure 1. Homemade screwdriver bits and drill chuck handle.
The drill chuck fit my hand well. For each screw I was working on I tried to make a bit that was the right
thickness for the slot and with a width to go completely across the screw head. Of course I was making
bits throughout the disassembly process.
By the time I got all this going the screws with Liquid Wrench on them had been sitting there for about a
week. With my new bits I tried again to loosen them, again using only intermediate pressure. No luck,
they were still stuck. Apparently Liquid Wrench doesn’t work well on early 20th century corrosion.
So I went to the auto store and bought a quart of transmission fluid and in a small wash bottle mixed a
small amount with some acetone. I put a drop or so on the screws I was working on and let them sit a
couple of days. And some of them came unstuck with just medium pressure! On the ones that were
still stuck I heated the area with my heat gun until the metal was just about hot enough you couldn’t
leave your hand on it, put some more mixture on, and waited another day or two. And these screws
came undone. I continued the process as I took the rifle apart, eventually getting all the screws out
without additional damage than had been done by the previous owner(s). Why this mixture works I
don’t know; the acetone and transmission fluid are not even soluble in each other. After the bottle sits a
while the two fluids separate.
So that is the method I would recommend. Make a bit that fits the screw nicely. Put on the
acetone/transmission fluid mixture and wait. Apply a bit of heat if needed. Have patience. One thing
though. Transmission fluid smells bad so don’t spill any on your wood work bench or you will be stuck
with the smell. When I used it I place aluminum foil under the rifle to catch any drops. Other times I put
the whole assembly (like the right side of the receiver) in a zip lock bag before applying the solvent.
4
Marlin Model 1897
The Disassembly
Initial Breakdown
Start with the main holding bolt on the right side of the receiver, as shown in Figure 2. Unscrew the
bolt, it will not come completely out of the receiver. You should be able to loosen the bolt with just your
fingers. If you need to use pliers, wrap a rag around the bolt so you don’t mar it.
Put the hammer at half cock or full cock; I
found that it works best with the hammer
at full cock. Hold the stock in your right
hand and the rifle forearm in your left
hand. Bend the stock to the right and the
rifle should come apart. You can also lay
the front of the barrel on the table with the
right side of the receiver up and push
down slightly on the receiver. The rifle will
come apart at the receiver with the right
side of the receiver connected to the stock
and the left side connected to the barrel.
The bolt and firing pin will still be in the left
side; slide it to the rear and remove to the
right. A photo of the bolt just before it is
lifted out is shown in Figure 3. When you
set the bolt down the firing pin will
probably fall out. That is not a problem.
Figure 2. Main assembly bolt on right side of receiver
Figure 3. Bolt pulled back and ready to be lifted out.
5
Marlin Model 1897
Next remove the rear most screw on the upper tang. This is shown in Figure 4. The On my rifle this
bolt was not stuck but the end had mushroomed very slightly, so I had to loosen and tighten it several
times to get it out. As you can see the head already had some damage. When you have this bolt out,
slide the stock out of the receiver. Two sight screws are also shown in the figure; these will be
discussed later.
So now lets start discussing screw threads, beginning with this stock screw. The major diameter of the
thread is 0.204 in, a little smaller than that of a 12-28 UNF screw. On my thread checker, the screw fits
both the 12-28 and 12-32 holes. This is probably because the stock screw is a bit smaller than a #12
and also because the thread checker is only 1/16 inch thick; it does not provide much resolution.. At
this time I do not have either a modern 12-28 or 12-32 screw to try in the tang - I am trying to find them.
Another interesting feature of the stock screw is a tapered shaft. At the end of the threads the diameter
is 0.208 in, just under the head it is 0.229 in. The taper must be to draw the stock in snug. Obviously it
complicates things if you need to make a replacement.
Figure 4. Stock removal screw and screws for sight.
Next the magazine tube and forearm will be removed. At the front of the forearm remove the two
screws in the collar – the right side collar screw is shown in Figure 5. Although the forearm will be
loose you cannot yet remove it; the magazine tube is holding it on.
Figure 5. Right side forearm screw.
Marlin Model 1897
6
The diameter of the forearm screw is 0.137 in, the same as a #6 modern machine screw. It will go
about 2 turns into the 6-40 hole on the screw checker before it jams. A modern 6-40 screw does screw
into the forearm mount so that size could be used as a replacement.
Next the magazine tube needs to be removed. At the front of the barrel push in the magazine tab,
shown in Figure 6, in and pull the magazine tube all the way forward. There will be a click when it
reaches the limit, there is a crude mechanism for holding it open.
Figure 6. Magazine tab and the dovetail the tube screws into to.
At the front of the barrel under the magazine
mounting dovetail that is shown in Figure 6,
a hole in the outer outer cylinder of the
magazine tube will allows access to the
mounting screw. Figure 7 shows what you
should see. Notice that the screw on my
rifle is a bit boogered up. Using a bit of the
proper size bit unscrew it bolt from the
dovetail mount in the bottom of the barrel.
However, I recommend that you do not pull
the screw out of the inner tube, tube; just
get it out of the dovetail in the barrel. You
can now now remove the magazine tube
assembly from the rifle and can then
remove the forearm.
At this point you should have five
Figure 7. The magazine screw seen through hole in
parts/assemblies. First, the rear stock and
outer magazine tube.
its mounting bolt. Second the right side of
the receiver. Third, the left side of the
receiver and the barrel. Fourth, the
magazine tube assembly with the mounting screw still in it. Fifth, the foream, its collar and the two
collar screws. You can lay the wood pieces to the side, we are not concerned with them.
It is ime for some initial cleaning. Using a toothbrush, maybe a dish washing brush, and perhaps a
cheap paint brush, clean the left side of the receiver and barrel with warm water and dish soap. Wipe
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Marlin Model 1897
dry, blow it off and wipe with the barrel with a rag with a little oil on it. There is more disassembly to do,
but it will proceed best if the receiver is a clean as possible. Do the same with the right side receiver
mechanism. Remember I suggested that you not take out the magazine screw. The reason is, if you
do, the spring will extend and you may have some trouble getting everything back together. The spring
does not have a neat ending and it can jump out around the latch the screw goes through. The
magazine assembly was the one part I did not clean with soap and water. I used mineral spirits. To
get the inside of the tubes I used a small dowel to push a rag soaked in mineral spirits. There is a slot
in the outside tube that will assist in sliding a rag through it. I suggest you clean in the same manner,
then lightly oil the tubes and set aside. If you want to take the magazine tube completely apart I think
you have to punch out the pin through the locking tab. Considering the bad reputation the magazine
tube has for causing problems I did not do this. You may also not want to go any further with the
magazine tube assembly.
Now we are going to do some more work on the left side of the receiver. You can set the right side of
the receiver aside. If you have not already done so, you may wish to put some acetone/transmission
fluid solution on the screws in the right side of the receiver, place it in a zip lock bag and set aside. On
my rifle several screws in the right side of the receiver were jammed.
Cartridge Stop, Ejector and Guide Spring
The inside of the receiver left side with the bolt removed is shown in Figure 8. This picture was taken
after everything had been cleaned and put back together. Yours probably won’t look quite as clean
even though some initial cleaning has already been done. There are two assemblies you can see. The
lower, held by one screw is the cartridge stop or cartridge cutoff. The top part mounted to the receiver
with two screws is the ejector and its housing.
Figure 8. Receiver left side with cartridge stop and ejector housing visible.
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Marlin Model 1897
The mounting screws as seen from the other side of the receiver are shown in Figure 9. These screws
all have narrow slots. As you can see if you look closely the slots have been messed up slightly by a
previous owner.
Figure 9 Cartridge stop (bottom) and two ejector housing mounting screws.
What you could not see in Figure 8 is the cartridge guide spring. It is at the top of the receiver and not
visible from the side. Figure 10 shows the receiver laid flat so the guide spring is visible. The guide
spring is mounted to the receiver with a screw that comes in from the top. Figure 11 shows the screws
at the top of the receiver. The two screws at the left are for mounting a sight or scope. The third screw
on the right is the guide screw mount.
Figure 10. Guide spring at the top of the receiver.
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Marlin Model 1897
Figure 11. Sight (left two) and guide spring mount screws on top of receiver.
Remove the screws holding the cartridge stop, ejector housing and guide spring. You can also remove
the sight screws at the top of the receiver. On the example rifle most of these screws were stuck and
required several days of work to get loose. The guide spring, ejector and cartridge stop assemblies
after removal are shown in Figure 12. Notice that the spring under the ejector housing has the sharp
end up and that it mounts in the forward hole. The ejector housing also has another screw head which
has a notch in it. I aligned the notch so the ejector fits into it. Is this what you are supposed to do?
You can remove the ejector by punching out a small pin, but there is no reason to do so just for
cleaning. The two ejector housing mounting screws are very close to 3-48, the major diameter is 0.096.
A modern UNC 3-48 screw could probably be substituted. At this point I have not found a modern 3-48
to try in the ejector housing.
Figure 12. Guide spring, ejector and cartridge stop assemblies, screw
sizes are approximate.
Marlin Model 1897
10
The cartridge stop screw has a major diameter of 0.138 in so it should be a #6. However, the screw
binds in my 6-40 UNF gauge. I tried a modern 6-40 screw in the cartridge stop; it was a bit loose but
could probably be substituted if not over tightened.
The guide spring is crimped at the front; the short crimped over part goes at the top. The mounting
screw for the guide spring has a 0.107 in diameter so should be a #4. I tried a modern 4-48 screw in
the spring; it was a bit tight but could probably be used.
The two additional screws on the top, placeholders for a sight or scope mount, had a major diameter of
about 0.1625 in, which should make them a #8, but I could not get them to fit any of the 8 gauge holes.
However, a modern 8-32 screw did fit the receiver, so if you need a replacement that is what to use.
Since I am sure you want to know, the spacing of the guide mount holes is 0.889 in as closely as I
could determine, or just under 57/64 inch. The reason for this particular spacing may be lost to history.
Clean the ejector, cartridge stop and guide spring assemblies with soap and water using the brass
brush, wipe with a lightly oiled rag, then put them back into the receiver. Also put the sight screws back
in. At this point you can put the magazine tube and forearm back on. Remember to put the forearm
and its collar in place BEFORE you put the magazine tube in. Don’t ask how I know this.
Bolt & Firing Pin
When you pulled the bolt out of the left side of the receiver and set it on the table the firing pin may
have fallen out. Figure 14 shows the bolt, looking from the top, with the firing pin still in. The extractor
is also still in the bolt.
As mentioned, the firing pin will fall right out. The extractor can be pried out with your fingers and a
small screwdriver. The firing pin and extractor are shown in Figure 13. Clean them in the usual
method, put them back into the bolt, and replace the bolt in the left side of the receiver. The bolt
replacement will be the reverse of the removal. Put it in a couple of inches behind the closed position,
hold it against the receiver, and slide it forward. You can now set the left side or the receiver/barrel
aside.
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Marlin Model 1897
Figure 14. Bolt, firing pin & extractor.
Figure 13. Extractor and firing pin.
Receiver Right Side
Next we move to the right side of the receiver, which has more moving parts. It is shown in Figure 15
and I have tried to identify some of the screws that will be removed. Some of the names I did not know
because the parts do not appear in the later model 39 version of this rifle. So I tried to assign a name
that made sense, at least to me. There does not seem to be a rigid order in which the parts are
removed, I will simply describe my take apart order. You can again see from the photo that the screws
have narrow slots and more custom bit grinding will probably be necessary.
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Marlin Model 1897
Figure 15. Receiver right side with screws marked.
Friction Spring& Lever
There is a piece of metal that rubs against the lever lever
to provide some lever friction and I called it the friction
spring. There is probably a different correct name. The
screw holding it comes in from the bottom of the
receiver. Remove this screw (one of the ones stuck on
my rifle), and then remove the lever pivot screw (also
was stuck). Use brush, soap and water to clean these
parts. After a bit of cleaning what you should see is
shown in Figure 16. And now the usual puzzle about the
bolt threads. The friction spring screw has a diameter of
0.133 in. The screw would go part way into the 6-40
hole on my modern screw checker before binding. A
modern 6-40 screw appeared to fit the spring very well,
so that size could be used for a replacement if needed.
The lever screw had the same diameter and also went
part way into the screw checker before binding. The
modern 6-40 screw fit into the rifle hole okay, although it
was maybe a bit loose. But it appears a 6-40 screw
could be used for a replacement lever screw if needed.
Maybe just not tighten it too much.
Figure 16. Friction spring & lever.
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Marlin Model 1897
Hammer and Hammer Spring
Next you can take out the bolt that holds the hammer spring. To keep parts from flying when the screw
comes out, clamp the spring to the tang while you remove the bolt. After the bolt is out slowly release
the clamp. Use a clamp with plastic jaws or use some cloth to protect the tang surface so it does not
get scratched. As an alternative, loosen the hammer spring screw a bit and then move the spring off
the hammer bushing. To reduce the spring tension put the hammer in the completely down position.
The hammer spring screw is a bit awkward to remove. The bit that removes it has to fit between the
upper and lower tang. I used a short hex bit and held the bit with a quarter inch open end wrench. Of
course I had to do some grinding on the hex bit before it would fit into the screw slot. This bolt was not
stuck on my rifle. The bolt holding the spring had a diameter of 0.185 in, close to a modern #10. It
would screw into a 10-32 gauge a small amount before it stuck. I tried to put a modern 10-32 screw
into the hole in the tang; it would only go about one turn and then stopped. So the hammer spring
screw appears to be a renegade with no easy replacement. The spring and screw is shown in Figure
17.
Figure 17. Hammer and hammer spring.
After removing the hammer spring unscrew the hammer pivot screw and remove the hammer.
The hammer pivot screw has a thread major diameter of 0.206 in, somewhat less than a modern #12,
which has a diameter of 0.216 in. On the screw checker it would fit into both the 12-28 and 12-32 hole.
The 12-32 seemed to be the better fit. At this time I have not found a modern 12-28 or 12-32 screw to
see if it fits the receiver hole. The shaft of the trigger pivot screw is 0.234 in which is very close to
15/64 inch. The shaft of a 15/64 inch drill bit would go through the hammer hole while a 1/4 inch drill bit
would not. So if a new hammer pivot screw was needed, it would be made from 15/64 stock. The
length of the 15/64 inch section of the bolt is 0.436 in. 7/16 inch is 0.4375 in so maybe that is supposed
to be the length. The length of the threaded section is about 0.125 in. As I mentioned, I have not yet
determined the screw threads. The hammer and pivot screw are shown in the above figure.
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Marlin Model 1897
If you look closely at the bottom of the hammer you can see a pin. This pin goes through a roller that
sits on the end of the hammer spring. For normal cleaning and maintenance there is no need to
remove this pin; it would only be done if the roller was being replaced.
There are two notches in the hammer, to hold it at half- and full-cock. On my rifle the half-cock notch
had some damage, with a small piece missing. The full-cock notch, which releases the hammer when
the trigger is pulled, appeared to be in good shape. At this time I have not tried to dress up either
notch.
Carrier
Next remove the carrier pivot screw and the carrier. Then remove the small screw in the carrier itself.
The carrier completely apart is shown in Figure 18. From top to bottom let’s call the three pieces the
rocker, rocker spring and carrier. Notice the small spring has the sharp end up. When you put it back
together set the spring in the carrier and then the rocker on top of the spring. The right end of the
rocker fits underneath the carrier. The small bolt, with the toothpick under it, appears to have two
functions. One, to hold the spring and rocker in the carrier and two, to limit the carrier movement. The
thread diameter on the small screw is 0.104 in, not a size that seems to match anything modern.
However, it does fit nicely into the 4-48 hole on the modern screw check and somewhat surprisingly a
modern 4-48 screw also fits the carrier. If you have to make a replacement for the screw it will be
important to get the head diameter right; it is about 0.21 inch.
Figure 18. The carrier assembly.
The carrier pivot screw looks complicated and, not a help, the threads don’t seem to match anything
modern. The thread diameter is 0.184 in, a bit smaller than a modern #10. However, the screw does
not fit a 10-32 hole on the screw nor will a modern 10-32 screw fit into the mounting hole. The shaft
diameter below the threads is 0.162 in and the length of the smooth section is about 0.55 in. Obviously
it would be best not to lose this screw.
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Marlin Model 1897
Receiver Side Spring
I call it the receiver side spring because I have no idea what the real name is. This spring does not
appear to be there on the later Marlin 39A for which I have a manual. Anyway the spring and the
receiver mounting slot it fits is shown in Figure 19. The side spring goes back into the receiver with the
hook at the end of the spring down as shown. The screw that holds the spring in has a thread diameter
of 0.106 in, just a bit smaller than a #4. It does not fit the 4-48 hole in the modern gauge, although a
modern 4-48 screw does seem to fit the receiver mounting hole pretty well.
Figure 19. Receiver side spring and mounting slot.
Trigger Spring
There is still a bit more. If you tilt the receiver and look down where the hammer spring was mounted
you see a trigger spring. This is shown in Figure 20 where the receiver is leaning against a sandbag.
This is one of those aggravating screws to remove because you have to have a short bit which fits
between the two tangs. Also it is easy to mess up the screw slot because you cannot get any pressure
on the bit. Also shown in this photo are sight mounting screws on the top tang. They are slightly out of
focus because I concentrated on the bottom tang. I will discuss the sight mounting screws in a minute.
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Marlin Model 1897
Figure 20. Trigger spring and its mounting screw, also sight screws on top tang.
After removal the trigger spring and screw are shown in Figure 21. The mounting screw has a thread
diameter of 0.138 in, a bit larger than a modern #6 UNF screw. The mounting screw would not go into
the 6-40 hole on the gauge. However, a modern 6-40 screw did fit the mounting hole in the tang, albeit
a bit loose. It could probably be used as a substitute if you did not tighten it too much.
Figure 21. Trigger spring, also the trigger mounting pin.
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Marlin Model 1897
I think this is a far as the receiver needs to be taken down. You could punch out the trigger pin and
remove the trigger. However, for cleaning purposes I don’t think it is necessary. If you were replacing
the trigger then of course the pin would be removed. The pin should be remove from left to right. On
later Marlin models apparently the big bolt could be removed; I did not see a way to do it on my rifle.
There was a shoulder on the bolt that prevented removal.
Tang Sight Mount Screws
As mentioned before, and shown in Figure 20, there are two screws used for mounting a sight. These
screws have a thread outer diameter of 0.166 in, slightly bigger than a #8. The screws would go part
way into either the 8-36 and 8-40 holes in the gauge. A modern 8-36 would go into the tang about 3
turns before jamming. I would guess the screws are like 8-38. On my rifle these screws do not look
like placeholders, they have large heads. Maybe at some point this rifle had another sight mounted on
it and the original placeholder screws were lost.
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Marlin Model 1897
Appendix A Modern UNC and UNF Screw Threads
The table below shows some of the specifications for modern UNC and UNF screws. The thread major
diameter has both a maximum and minimum value. The Allowance field is an additional amount that
can be added to the major diameter if the screws are plated. 3A screws are of a tighter tolerance than
class 2A. The minor diameter is at the thread root.
Allowance
Major dia, in
Minor dia, in
Size
Class
inch
Max
Min
0-80 UNF
2A
0.0005
0.0595
0.0563
0.0446
0-80 UNF
3A
0.0000
0.0600
0.0568
0.0451
1-64 UNC
2A
0.0006
0.0724
0.0686
0.0538
1-64 UNC
3A
0.0000
0.0730
0.0692
0.0544
1-72 UNF
2A
0.0006
0.0724
0.0689
0.0559
1-72 UNF
3A
0.0000
0.0730
0.0695
0.0565
2-56 UNC
2A
0.0006
0.0854
0.0813
0.0642
2-56 UNC
3A
0.0000
0.0860
0.0819
0.0648
2-64 UNF
2A
0.0006
0.0854
0.0816
0.0668
2-64 UNF
3A
0.0000
0.0860
0.0822
0.0674
3-48 UNC
2A
0.0007
0.0983
0.0938
0.0734
3-48 UNC
3A
0.0000
0.0990
0.0945
0.0741
3-56 UNF
2A
0.0007
0.0983
0.0942
0.0771
3-56 UNF
3A
0.0000
0.0990
0.0949
0.0778
4-40 UNC
2A
0.0008
0.1112
0.1061
0.0814
4-40 UNC
3A
0.0000
0.1120
0.1069
0.0822
4-48 UNF
2A
0.0007
0.1113
0.1068
0.0864
4-48 UNF
3A
0.0000
0.1120
0.1075
0.0871
5-40 UNC
2A
0.0008
0.1242
0.1191
0.0944
5-40 UNC
3A
0.0000
0.1250
0.1199
0.0952
5-44 UNF
2A
0.0007
0.1243
0.1195
0.0972
5-44 UNF
3A
0.0000
0.1250
0.1202
0.0979
6-32 UNC
2A
0.0008
0.1372
0.1312
0.1000
19
Marlin Model 1897
6-32 UNC
3A
0.0000
0.1380
0.1320
0.1008
6-40 UNF
2A
0.0008
0.1372
0.1321
0.1074
6-40 UNF
3A
0.0000
0.1380
0.1329
0.1082
8-32 UNC
2A
0.0009
0.1631
0.1571
0.1259
8-32 UNC
3A
0.0000
0.1640
0.1580
0.1268
8-36 UNF
2A
0.0008
0.1632
0.1577
0.1301
8-36 UNF
3A
0.0000
0.1640
0.1585
0.1309
10-24 UNC
2A
0.0010
0.1890
0.1818
0.1394
10-24 UNC
3A
0.0000
0.1900
0.1828
0.1404
10-28 UNS
2A
0.0010
0.1890
0.1825
0.1464
10-32UNF
2A
0.0009
0.1891
0.1831
0.1519
10-32UNF
3A
0.0000
0.1900
0.1840
0.1528
10-36 UNS
2A
0.0009
0.1891
0.1836
0.1560
10-40 UNS
2A
0.0009
0.1891
0.1840
0.1592
10-48 UNS
2A
0.0008
0.1892
0.1847
0.1644
10-56 UNS
2A
0.0007
0.1893
0.1852
0.1681
12-24 UNC
2A
0.0010
0.2150
0.2078
0.1654
12-24 UNC
3A
0.0000
0.2160
0.2088
0.1664
12-28 UNF
2A
0.0010
0.2150
0.2085
0.1724
12-28 UNF
3A
0.0000
0.2160
0.2095
0.1734
12-32 UNEF
2A
0.0009
0.2151
0.2091
0.1779
12-32 UNEF
3A
0.0000
0.2160
0.2100
0.1788
12-36 UNS
2A
0.0009
0.2151
0.2096
0.1821
12-40 UNS
2A
0.0009
0.2151
0.2100
0.1835
12-48 UNS
2A
0.0008
0.2152
0.2107
0.1904
12-56 UNS
2A
0.0007
0.2153
0.2112
0.1941
1
/4-20 UNC
1A
0.0011
0.2489
0.2367
0.1894
1
/4-20 UNC
2A
0.0011
0.2489
0.2408
0.1894
1
/4-20 UNC
3A
0.0000
0.2500
0.2419
0.1905
2A
0.0011
0.2489
0.2417
0.1993
1
/4-24 UNS
20
Marlin Model 1897
1
/4-27 UNS
2A
0.0010
0.2490
0.2423
0.2049
1
/4-28 UNF
1A
0.0010
0.2490
0.2392
0.2064
1
/4-28 UNF
2A
0.0010
0.2490
0.2425
0.2064
1
/4-28 UNF
3A
0.0000
0.2500
0.2435
0.2074
1
/4-32 UNEF
2A
0.0010
0.2490
0.2430
0.2118
1
/4-32 UNEF
3A
0.0000
0.2500
0.2440
0.2128
1
/4-36 UNS
2A
0.0009
0.2491
0.2436
0.2161
1
/4-40 UNS
2A
0.0009
0.2491
0.2440
0.2193
1
/4-48 UNS
2A
0.0008
0.2492
0.2447
0.2243
1
/4-56 UNS
2A
0.0008
0.2492
0.2451
0.2280
21
Marlin Model 1897