How to Fit an Older Model 37 Barrel

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.22LR
Posts: 26
Joined: Mon Sep 02, 2013 12:16 pm
PostPosted: Thu Sep 19, 2013 8:09 am
Does anyone know the exact gunsmith process of fitting a barrel to an older model 37? Is it just a head space thing, or is there serious barrel smiting involved? Is it possible to have a barrel that is fitted to another gun fit on yours with no problem? Can I just head space a barrel myself and if it checks out, is it okay to use or is there something I'm missing something? My local gun guy might know someone with an ICYL barrel for my pump and I wanna jump on it if possible and I am wondering exactly what my shotgun will have to go through to get it working properly. He says that pre-855,000 guns are interchangeable with other pre-855,000 guns based on how old your barrel and shotgun are, but I have heard this is false from a variety of forum members and old timers at the gun club. Is there any truth in what he says or has he been miss-informed?

Thanks, Flax
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.270 WIN
Posts: 293
Joined: Sun Nov 25, 2012 8:44 am
PostPosted: Thu Sep 19, 2013 8:58 am
Does anyone know the exact gunsmith process of fitting a barrel to an older model 37?


See below

Is it just a head space thing, or is there serious barrel smiting involved?


See below, needs machined on a lathe

Is it possible to have a barrel that is fitted to another gun fit on yours with no problem?


About the same odds as hitting the lottery

Can I just head space a barrel myself and if it checks out, is it okay to use or is there something I'm missing something?


Missing something

My local gun guy might know someone with an ICYL barrel for my pump and I wanna jump on it if possible and I am wondering exactly what my shotgun will have to go through to get it working properly.


Keep in mind that it will cost at least 100.00 to have a barrel fitted. That translates into shipping both ways, 75.00 that Les says he charges, I do not know the local rate here by me.

He says that pre-855,000 guns are interchangeable with other pre-855,000 guns based on how old your barrel and shotgun are, but I have heard this is false from a variety of forum members and old timers at the gun club. Is there any truth in what he says or has he been miss-informed?



He is smoking crack. Just kidding, he had it turned around.

The newer POST 855,000 barrels are interchangeable.

The older barrel threads (pre-855,000) had a pitch to the threads, just like on a bolt. There is a dimensional relationship between the barrel face, the shoulder at the end of the threads, the face of the receiver and an internal shoulder.

This is why the barrels are serial nbr'ed to the receiver. There will be a serial nbr on the front face of the receiver, running vertically next to where the barrel goes in, and the serial nbr on the barrel that also has a - (dash nbr) to indicate choke. Such as 543123-2 indicates a MOD choked barrel.

Ithaca choke marking system: "1" for Improved Cylinder; "2" for Modified; "3" for Improved Modified and "4" for Full choke. There were also Skt marked barrels (or maybe nbr 5)

In order to fit the barrels (from what I can tell by observation and talking to other folks) the barrels were screwed into the receivers and a "witness mark" put on them. If you look at the older barrels most if not all will have the witness mark. All of mine do (older ones). The witness mark allowed them to align the barrel in fixtures to cut the thread interrupts, the extractor cuts and to put the barrel lug on.

Most pre- barrels will not even start. You can fudge them by backing them out a little but then they won't headspace correctly. If they do start, they will usually stop before going into position.

Because the threads have a "pitch" to them, the barrel is actually pulled into the receiver a small amount, just like a bolt is pulled into a nut/threaded hole when turned. A 1/4 turn does not translate into much movement, but it is there and has to be taken into account.

To fit a barrel, the barrel face and the shoulder have to be carefully machined on a lathe a little at a time until the barrel will go into the receiver, start into the threads and then when turned, bottom out with the all the aforementioned features in alignment. A person has to understand the dimensional relationship before hacking away at the metal.

As I posted, there are 2 gunsmiths that I know of that I would trust to fit the barrels. Other good gunsmiths if they take the time to understand the dimension relationships could do them also, but they have to take the time to look at the design.

The post 855,000 barrels simply use parallel V grooves, which allows barrels to be swapped back and forth. Sometimes due to pre-CNC machining practices/tolerances, even those might need a little adjustment.

.22LR
Posts: 26
Joined: Mon Sep 02, 2013 12:16 pm
PostPosted: Thu Sep 19, 2013 10:03 am
Wow, now I know where that $75 is going. After I see how this barrel works out I'll give Gerald a call and see what he charges. My gun guy also said that he has exchanged barrels on earlier Ithaca 37's without issue multiple times. Each time he says that they lined right up and interchanged without issue. He either has his serials numbers messed up or he's just lucky. With that kind of luck he should have bought lottery tickets instead of shotguns. He also told me he has a m37 in 20ga that has a 3 barrel set with serials all matching the shotgun. Man would I love to get one of those. Save me a lot of trouble. I can't fathom the price tag however. That must be very rare.

.270 WIN
Posts: 218
Joined: Wed Dec 19, 2012 12:26 pm
PostPosted: Thu Sep 19, 2013 10:18 am
Ron Sharp in Ontario Canada is the only person that I know of, that can do a sure thing fit on most old 37s. He has bought out bankrupt Ithaca Company owners twice and has a huge stock of parts, including old BLANK barrels. He used to work for Ithaca and now has a shop of his own. He would fit a barrel to your receiver just as the original would including stamping the serial number onto your new barrel. You get to keep your old as it is still good. You might get "LUCKY" fitting an old barrel from a different gun onto your old gun, but fit might not be exact and serial would be wrong. Ron Sharp's method is exact, but not cheap. $300 or $400 for the job and I don't know if that includes shipping. Ron is old school and does not have internet, not even fax. You write him a letter or phone him. Ron is pretty is elderly and don't know how long he will still be working. If you need either, PM me. Thanks Donald.
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.270 WIN
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PostPosted: Thu Sep 19, 2013 10:20 am
Flax wrote:Wow, now I know where that $75 is going. After I see how this barrel works out I'll give Gerald a call and see what he charges. My gun guy also said that he has exchanged barrels on earlier Ithaca 37's without issue multiple times. Each time he says that they lined right up and interchanged without issue. He either has his serials numbers messed up or he's just lucky. With that kind of luck he should have bought lottery tickets instead of shotguns. He also told me he has a m37 in 20ga that has a 3 barrel set with serials all matching the shotgun. Man would I love to get one of those. Save me a lot of trouble. I can't fathom the price tag however. That must be very rare.



He either has his serials numbers messed up or he's just lucky.


I have 5 pre-855,000 16ga guns at the house and an extra barrel. and another 16ga barrel on its way. add 3 post 855 16's and 2 post 855 12's.

Of the 6 pre 855,000 barrels I have at the house NOT 1 of them will even start in another receiver. Not 1.

He also told me he has a m37 in 20ga that has a 3 barrel set with serials all matching the shotgun. Man would I love to get one of those. Save me a lot of trouble. I can't fathom the price tag however. That must be very rare.


You need to find out what he wants for that set (if it is for sale). There are a couple folks on the Shotgunworld Ithaca forum that might be REALLY interested in it.

.22LR
Posts: 26
Joined: Mon Sep 02, 2013 12:16 pm
PostPosted: Thu Sep 19, 2013 10:23 am
He wouldn't even give me an answer, It's in his private collection next to his riot model. He's not giving that up to save his live. I don't know where he finds this stuff, but that must be how he makes money at it.

Copper BB
Posts: 2
Joined: Sat Feb 01, 2014 3:47 pm
PostPosted: Sat Feb 01, 2014 5:44 pm
When I bought a new barrel for my older Model 37, I had to have the head space reworked. Sent the gun to Ithaca with the new barrel and they took care of it. Both the new and the original barrel work fine now. I imagine they needed to machine the face a few thousandths to fit it up right.

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