Fixing the Marlin "jam"

Brad

Benevolent Overlord and site owner
Staff member
Either I am missing something or that design is right on the raggedy edge of not
working all the time. The wear I saw in the video looked like just barely enough to
get through the surface finish, not any significant dimensional change. Is there
something that I am missing?

Bill
You are not seeing anything wrong, it is on the ragged edge. My 32-20 had the problem when brand new.
Using a minimal design and a soft metal for the carrier makes it a recipe for disaster.

Hey Bill, what profession do we blame for the design? Bet it is someone you know.....
 

Pistolero

Well-Known Member
Amazingly small dimensional change to cause total mayhem. IMO, as an engineer,
that is a bad design, crying out for something to permit it to work with a tiny bit of
wear. I have and like Marlins, but this is just weird.

Yeah, Brad, but not recognizing this and going out there to figure out how to make
the design more tolerant of wear is just stupid management. This should have
been recognized long ago, (if it happens more than 1 in 1,00) and an engineer
assigned to figure out what the issue is and FIX IT. Leaving a marginal design
alone is unacceptable.

As a test pilot friend once pointed out when I questioned him about the flying
qualities of a particular very popular and aesthetically beautiful homebuilt
aircraft design that both he and an AF test pilot mutual friend had flown....
"Well, they don't sell landing gear assemblies in a one-to-one ratio with
the airframes." The design was entirely unstable in pitch at landing speeds
below a certain, very likely to be reached, speed. An Australian test pilot,
hired to evaluate the design before the Aussie FAA would permit the kits
to be sold, flunked it cold. A tail redesign was required, and the lower speed
pitch stability was then fine. The solution for this issue was absolutely well
known, obvious as hell, but the managment didn't bother even though they
were selling a lot of replacement landing gears, which should have been
a glaring red light that they had a problem.

Marlin should wonder why they sell a lot of carriers. Should sell nearly zero.
Marginal designs are out there in every field. Good testing and engineering

This is one thing that I did at work, with computer modeling, studying "design
margins". Basically, is the design just standing on the edge of an abyss, and
will a small change in some tolerance accidentally "step off the edge". Without
a design margin review, or redesign based on field experience, no design is
properly done, IMO. I could test designs (primarily stress and thermal, not kinematics
most of the time) and throw in variations and see how it would affect it. Sometimes
a design that had been really good for many years would suddenly have lots of
parts failing testing. A critical spec had been missed, often by just a bit, but the
design was intolerant of even small spec errors. This is a bad design.

Bill
 
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Brad

Benevolent Overlord and site owner
Staff member
I have a feeling that Marlin figures they will last long enough to make it thru the number of cycles Joe Hunter will run it thru.

The carriers look like they are cast but obviously not from a high carbon steel. Better material and some heat treat, like Ruger would do, would prevent the issue.
 

Ian

Notorious member
The 336s don't have the same problem. Carriers ar hard as coffin nails. Excess mag spring tension or out-of-spec carrier/lever/floorplate and/or extreme wear/tolerance stacking typically is the cause. Most common fix is bend the carrier nose to keep the second cartridge from camming-over and kicking up the carrier nose. The 1894s are the ones with the real material/design defect with the carrier.
 
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