Ithaca Model 37 Troubleshooting

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PostPosted: Wed Feb 10, 2016 7:11 pm
twistedoak wrote:raven will know better ,
but that looks like a weak mainspring.
ammo type should not effect that
as far as ammo dumping you got it with a worn shell stop.
if you sense play in the lock up look at the slide stop.
I've had to replace them before when I had excess play.the area is very small where it contacts the slide and its a high wear area


I feel for you guys across the pond ,the parts were talking about are common and cheap here.
I have everything listed above in my spare parts box.

I also get the feeling your m37s are shot a whole bunch more then your avg m37 in the states.
over here m37s aren't considered range guns ,they are guns that get kept in a closet till small game season ,and put back after it closes



Twisted, I think you nailed it. The only other problem to a light strike is that it could be a broken spring. A broken coil spring can work fine some times and then the two pieces can "slip" and you have light strike.

If the bolt was really loose and it turned out to be a headspace issue, you would know it.

That's about all I can add to this conversation
--Jim
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PostPosted: Thu Feb 11, 2016 6:27 pm
ravengunsmith wrote: I've shot Kents (which is Gamebore here)
without an issue in my citori and they ejected fine (that has a tight Chamber, too)


Interestingly, I believe that the 37 has a "loose" chamber, certainly when compared to my BPS and I thought that the "low head",( under 10mm) was allowing over expansion of the hull which was in turn grabbing the chamber walls. High metal (16mm +) seems to alleviate the problem
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PostPosted: Wed Feb 17, 2016 7:04 pm
Mine are quite tight. all of them hate reloads.
--Jim
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PostPosted: Mon Jun 13, 2016 4:18 am
Well gentlemen to revisit the 'fail to extract' issue I am afraid that I have some more questions to put to you.
During a particularly long IPSC competition stage this last weekend I experienced the mother of all fails to extract. I was unable to finish the stage, so I made the gun safe and let it cool. when I eventually managed to remove the offending case I decided to keep it for later examination (photographs). I discovered that the magazine cap was a little loose despite being tightened at the start of the stage. This seems to be a recurring issue and, I believe, is central to the problem.
Upon examination, I saw that the case had bulged slightly, forward of the rim, had flowed into the extractor cut outs and had deformed behind the rim quite substantially. This seemed like a headspace issue, with the barrel loosening within the interrupted threads. I decided to research a little further as I had formed half a plan to fit a grub screw into the side of the mag cap to lock it in place. Checking the exploded views of the '37 from various sources, I was surprised to see the "mag nut pin" and its associated screw and spring. This is something that to me was hidden in plain sight, as I have always *assumed* that the ball detent was what prevented the mag cap from loosening. (to quote Jack Reacher, to assume makes an ass of u and me!) I would be grateful if anyone could shed some light on the fitting of these parts as my '65 does not have them, nor any place to fit them.
My research eventually found a Kings Ferry field maintenance manual which showed a different approach to the loosening mag cap.
In it, during assembly, it shows the yoke being hit by a hammer and wooden drift to contact the rear edge of the mag cap and so fix it in place prior to tightening the yoke screw. Is this common practice? It is contradictory to all other model 37 manuals that I have seen, which state "to dis-assemble screw the mag nut clockwise until it clears the barrel lug, then rotate the barrel" No mention of removing the yoke screw and drifting the yoke back first.
my '65 has wear marks from the yoke screw and yoke itself from where it has always been positioned, about 1/8" behind the mag cap when cap is locked into the barrel lug. I thought that maybe my ball detent was weak, but, research showed me that some mag caps are available without the dimples for the ball to engage. I thought that I knew '37s, it would seem not and I now seek further education from you all! Please note I am aware of the need to replace my yoke screw, it was 'wrong screwdriver' damaged before my ownership!!

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PostPosted: Tue Jun 14, 2016 10:20 am
what is the year again?
the loosening at the barrel lug may or may not have nothing to do with the stuck shell.
I say this because in theory the barrel threads are what set and lock in the headspace ,not the tightness of the mag nut.
excessive wear can cause headspace issues,however a misaligned yoke can also bind a shell in the chamber.
much like you describe

the mag nuts went though several variations mostly driven to reduce cost .
the biggest variation was the early pin type,i remember reading that one of the reasons they were dropped is because there were cases of people over tightening them.
in general use they all work fine.

the practice of pinning the mag nut with the yoke was adopted for high use guns by law enforcement., to prevent barrel removal
military guns required a fixed non removable barrel(after WWII)
the reasoning behind fixing the barrel is unrelated to the ability to fire the gun,but more toward swinging it like a bat or attaching a bayonet
how many shots did you fire?
I don't pin the nut on any of my hunting guns ,but if your sending a few hundred down range at a go ,i'd consider pinning it with the yoke.
i'd also check the tightness of the stock bolt often.

as far as the stuck shell ,
my first impression is to decide if the shell itself could be the oddball and a bad one .
then as I said above i'd check to see if the yoke was aligned properly
lastly i'd wonder if the gun was locked up completely when the shell was fired
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PostPosted: Tue Jun 14, 2016 2:01 pm
Hi Twisted,
My '37 is a 1965 model, field barrel featherlight. I believe that the loosening of the mag nut permitted the barrel to begin partial rotation. On the course of fire that I was shooting, I had fired about 20 shots rapid before the fail. During my reloads, the heat, even through the heatshield, was quite intense. With my speedloading technique, the gun is spun over rapidly and shooting continues after just a few seconds (some shooters keep the gun in the shoulder and load right way up)
The yoke on this gun was perfectly aligned, my barrel will not rotate if the yoke is mis-aligned (the tolerances are that tight)
My question about pinning the mag nut with the yoke arose after finding an Ithaca Gun Co. manual (Kings Ferry) that I had not seen before. It was neither military or law enforcement that I could make out, and included the model 87
I am fairly confident about the ammunition and the lock up. Also, the stock bolt on this gun is modified with a locking nut.
Thanks for your input and information

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PostPosted: Tue Jun 14, 2016 4:34 pm
The old style magazine nut you refer to was used from 1937 and phased out going into 1955. As stated before it was for the most part a cost cutting measure. A number of other short cuts took place that year including no checkering on field grade stocks, and simpler machining on the top of the receiver. I agree with Twisted Oak on the barrel line up. I have a 37 that the shells would bulge in the extractor cut outs and become firmly lodged in the barrel. The barrel would not bind in the yoke when installed or removed. I put the barrel on another 37 and it shot fine. I put the barrel from the second gun on the problem gun and had the same problem leading me to believe that the cut outs where not aligned with the extractors. After adjusting the yoke a number of times followed by test firing I was finally able to get things lined up just right and the gun will work with any barrel. As for the yoke assembly procedure you mention I have also heard of it but only for law enforcement use.
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PostPosted: Tue Jun 14, 2016 5:44 pm
This is very strange ,Gentlemen. Cutcher, you described my jammed case perfectly, but in my case it only happened when the gun was hot and the mag nut loose. I guess if the barrel moved marginally so that the extractors did not quite line up then we are approaching the cause. Prior to this jam the gun had fired about 100 rounds perfectly that morning, and the last jam before that was probably 400 rounds ago. I have been tightening the mag nut prior to shooting (it was always a little loose) So maybe the yoke pushed forward to the mag nut will cure the problem? I can but try.
I still don't understand why the ITHACA Kings Ferry NY maintenance manual is quite specific about this procedure, and yet you Gentlemen refer to it as military or LE. I tried to load up the manual for you to see but the site will not accept PDF files. There is reference in the preface about 1993 production guns and the sling stud, but that is the only date reference in the manual
Thanks as always for your time and patience with a puzzled Brit!
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PostPosted: Tue Jun 14, 2016 7:03 pm
Cutcher and twisted are both spot on. They know as much as anyone outside the factory.

Remember, it only take a few thou in any one place to get the entire firing/extraction mechanism to malfunction. If the yoke is too loose and the barrel heats up, that could be all it takes to cause that mechanism to foul. Especially the yoke. When I sold new Ithaca's I found out that shipping often caused the yoke to misalign and require a tune up. (UPS and FedEx are so gentle) I'd give you a torque spec for that screw but I have learned that every gun is a little different and to trust your eyes and how the barrel attaches and detaches.
--Jim
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PostPosted: Wed Nov 16, 2016 6:40 pm
As an update, the '65 has not had a jam since my last post and the '71 likewise. The '65 mag nut is locked into place with the yoke as per the KF manual but only when I have absolutely got the slot in the roof of the receiver perfectly in line with the top extractor cut out, problem gone!
The '71 did not have a yoke and the mag tube is non standard. I got a friend to pick me up a yoke when he was stateside. Of course it did not fit and needed to be packed out. I now position this yoke against the heat shield front mount as there, it holds everything solid. Again, nothing is locked up until the extractor slot and receiver slot are perfectly aligned. It seems to me that with just a little assembly care (and the advice of my peers across the pond!) the problems with my favourite shotguns have gone away. Thank you gentlemen!
PostPosted: Thu Nov 17, 2016 10:25 am
Thanks for the update...glad it worked out for you.
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PostPosted: Thu Nov 17, 2016 9:24 pm
For the interest of readers of this thread I have attached some screen shots of the KF manual discussed previously, the front page for reference and fig. 16, re-assembly of the yoke
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PostPosted: Fri Nov 18, 2016 10:16 am
Thanks..............
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PostPosted: Thu Oct 11, 2018 11:21 am
Whilst browsing the current gun company catalogue (and hoping for a UK importer to bring some in!) I couldn't help but notice that new guns seem to have the mag nut pinned by the yoke, perhaps a recommendation now?
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PostPosted: Thu Oct 11, 2018 4:14 pm
my guess is it has more to do with the new choke tube barrels.
kind of like with military guns ,with tubes theres no need to remove a barrel unless your cleaning.
with older fixed choke guns, many owners had 2 or 3 barrels of different chokes depending on what they were hunting .
pinning the yoke would be pita for every barrel change
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PostPosted: Thu Oct 11, 2018 6:27 pm
As always Sir, you make perfect sense.
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PostPosted: Sun Dec 02, 2018 7:46 pm
A couple of questions if I may,
I am in the process of acquiring a couple of M37's, a 16g and 20g. I have checked them out and both, oddly had exactly the same fault. The slide pin on both guns was sheared at the narrow part. I have made some enquiries about getting the pins but we do seem to have problems with parts from the States. My first question is this, are the pins on a 20g, 16g, and 12g all the same size? Indeed, are the slides the same size? I ask as my best course of action may be to get these pins machined over here, if, that is, I can use a 12g pin as master.
Also, when driving out the slide pin check pin, is it done from the top or bottom of the slide?
Is the check pin re-usable?

Thanks in anticipation :)

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PostPosted: Mon Dec 03, 2018 5:47 pm
To my knowledge the slide pin is the same on all gauges. I believe the slide stop pin is supposed to be re usable. I can't remember if I have ever had one out personally though.
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PostPosted: Wed Dec 05, 2018 6:28 pm
Having got no reply from Ithaca regarding parts, I guess they are like all US companies now, not supplying gun parts outside the USA and Canada, Numrich making that same statement and Brownells UK having the grand total of 4 Ithaca parts, I decided to fabricate.

My initial intention was to turn the parts on a lathe but with a broken cutter I was forced to re-think. I sourced some 4.5 mm steel rod (luckily exactly the right size!) and determined that
1, the pin did not need to rotate and
2, by leaving more material in the pin it would be somewhat stronger.

As stated by Cutcher, the pins are all the same size, not calibre dependant so I made two and left one of them in my 1965 go-to pigeon gun. If it was going to be unreliable I would soon know!

I cut a slot for the check pin 1.5mm deep using the original to give the dimensions. Refitting, I marked the shallow scooped out area that aligns with the slide underside and then shaped with a half round file, finishing with a screwdriver slot for taking down. Although it is free moving, it is quite a snug fit, so I turned a small oil way groove to retain a little lube. Re-assembling proved the part to be fit for purpose so I will shortly be able to take possession of 2 new (to me) 37's. There is a necessary delay as once the guns are back in one piece they have to go to the proof house for restriction certification (Red Tape!)

In case any other reader has this problem, (manifested by being unable to remove the forend when pulling the slide pin back) This is the procedure;

Lay the gun on a flat surface, on its right hand side, with the receiver on a piece of wood to raise it and so lay perfectly flat (action bar uppermost)
Hold the slide pin across to release (will be downwards with gun on its side)
While holding the pin, tap the receiver on the left side with a soft rubber hammer or protected by wood, this will cause the broken piece of the pin to fall into the pin cavity so you may now pull the slide assembly clear

It took me a while to work this out as taking down this assembly is usually done with the gun upside down. Hope if you break a pin this helps (of course in the States you can get a new pin for pennies! :|
For what its worth, the check pin is driven out from the bottom to the top of the slide and yes it is re-usable
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PostPosted: Wed Dec 05, 2018 7:22 pm
While I was sorting out my pins a friend called who had lost his safety catch out in the field together with the detent pin and spring. It is not the first time I have heard of this and as mentioned above parts for Ithaca's are almost unobtainable over here. I offered him one of my rotating ambidextrous safeties (detailed in modifications thread) but he said he would like a standard, right handed, push through one.

I silver solder brazed a piece of 2mm steel bar into a 1/4" steel rod and filed to shape, check fitting with one of my guns. To prevent further loss, I made the catch about 1mm longer on the left hand side so that there is now a 'riser' retaining the pin when in the Safe position, as opposed to the down slope as standard. A brass detent pin and longer spring complete the set.

While making and testing, it occurred to me that the trigger should actually prevent the Safety catch from falling out, even if the pin and spring were not in place. So I am not sure if my friend was being 100% truthful about his loss
Nonetheless, a friend in need as they say...……….
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PostPosted: Thu Dec 06, 2018 6:44 pm
You do nice work.
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PostPosted: Fri Dec 07, 2018 4:46 pm
Thank you Sir, it’s a ‘ needs must ‘ situation for Ithaca in the UK things like springs and pins I tend to buy mixed bags as they become available, and usually can find a suitable candidate for most jobs. I constantly scour the auctions for guns and do not discount wreckers that could be donors. Any serial numbered receiver has to be held on licence as a complete gun, it can only be removed if cut up by a registered firearms dealer. I have done this with a couple of write-off Savage Stevens but all my Ithaca’s are for saving. Making the parts I need is rewarding in itself, it’s a part of my shooting hobby and I enjoy it. This forum is my first Ithaca reference source, it has been most enlightening and I post my projects to hopefully encourage others. I hope the forum revives with new owners and old alike discussing our favourite firearms.
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