Ithaca M37 chop shop questions

[SuA]

Hi everyone,

Eurotrash here. Been lurking for 3 years, and finally have something to post.

I'm planning one doing something totally loathsome: chopping up a perfectly good Ithaca 37 12 gauge.
Before someone questions the legality (rather than questioning the morally reprehensible nature of chopping up an M37), it is legal to do here if done through the proper channels (and if minimum barrel length is at 30cm or overall length is 60cm).

Now, a few years ago our gunlaws were changed and a time of uncertainty followed. This caused a lot of people to sell their guns. A lot of pump action shotties were turned in at gun stores for next to nothing. I'm looking to get me a used Ithaca M37 smooth bore and turn it into something similar as to the shotgun pictured in the attachment. Exact barrel length is still unknown, as I will decide when I actually get it. I suspect it will be around 13 to 15 inch in barrel length?

I however have no extended knowledge of the Ithaca Model 37 line. Most of what I do know, I got from researching the design and from reading this forum. Now, I'm stuck with MANY questions, and I was hoping you guys could help me out.

1) Steel vs Lead: From when on are M37's safe to shoot with steel shot? (Not interested in current production models btw, only the 'oldschool' ones)

2) Slugs: Are there any kinds of slugs that should not be shot out of a smooth bore M37 with a chopped barrel (no choke)?

3) Wear: What areas of the shotgun should I check specifically for wear when picking the weapon to use in my project? I know the shell stop spring tends to weaken or foul and cause it to dump live rounds out of the mag tube when cycling the action. I also know of the drag marks on the magazine tube from the pump and how it can usually be fixed. What else is there that I should check?

4) Model: What specific models should I prefer for my modifications? I'm obviously going for smooth bore, non-ribbed, with classic pump (non-deerslayer), pref 3" chamber and I'd rather not use an M87. But more specifically, which models should I avoid, and which should I prefer if given the choice?

5) Measurements: I need to know the exact length from the front of the receiver to the front of the mag tube (including the fitment thingy on the barrel, basically the full length of the barrel in the picture attached, starting from the receiver). Can someone measure this for me?

6) Mini-shells: Do mini shells feed well in all M37's or is it a bit hit & miss? (just for fun, not really important at all)


Thanks for your input!

 

[MachIVshooter]

Welcome aboard SuA

First off, I don't think there's anything wrong with chopping a 37. Of course, I'll lob the barrel on just about anything if I feel it'll work better for me that way. I think the classic wood'n'blued M-37 looks great with a short barrel and a tube that extends most, if not all the way to the muzzle. Lucky for you, you can go a bit shorter than we can here in the US without a title II tax stamp (18" for shotguns to stay title 1 here).

Anyway, on your questions....

1) Steel vs Lead. That is a function of the choke rating. Generally, anything full, extra full or super full needs to be steel rated. But if you're lobbing the tube, it'll be cylinder bore, so no worries.

2) Slugs. Have at it. With cylinder bore, there is no risk. However, if an early gun, the magnums are gonna be harder on it.

3) Wear. The M37 is a well built gun that is the culmination of both genuis designers John Browning and John Pedersen. I'd just give it the same thoughtful once-over I'd give any other gun.

4) Model. Well, I'd probably avoid the aluminum receiver Ultralites, since it sound like you wanna put this thing through it's paces. There were, of course, models factory made pretty much the way you want yours. I'm not sure when they started chambering them in 3", but it'll be marked.

5) Measurements: I need to know the exact length from the front of the receiver to the front of the mag tube (including the fitment thingy on the barrel, basically the full length of the barrel in the picture attached, starting from the receiver). Can someone measure this for me?

That's gonna depend on the model. They may have 3, 4, 5, 6, or 8 round tubes. From the length you're talking about going with the barrel, a 3 round tube is about all that's gonna fit.

6) Mini-shells. Having no experience with a 37 and mini shells, I'm afraid I can't help you with this one.

Have fun with your project and happy shooting!

 

[roo_ster]

SuA:

I would do what you are doing to one of my shotguns, were it not for our silly NFA SBS laws. I am not sure I want to have to call the BATFE after HD incident after using my SBS.

The shotgun in the image looks about perfect for home defense or self defense. Just enough bbl to get beyond the mag tube & no more and a real stock. Handy, handles well, and still usable as a bludgeoning instrument. What's not to like?

I suspect sabot slugs will not work well in a smooth bore.

 

[Daveboone]

An eighteen inch bbl 37 slug gun is pretty easy to come by, and is a very compact shotgun. I would think rifled sights would be more useable and practical (especially with the traditional high visibility orange triangle front sight factory mounted on them). I have found a number of them (primarily 80s production) to have a bit of a loose leaf sight, which a simple drill and tap for an allen head set screw takes care of. Dont worry about the magazine tube wear. All pump guns get it.

 

[MachIVshooter]

I suspect sabot slugs will not work well in a smooth bore.

Well, they'll fire fine. Hitting what you're aiming at, on the other hand.........

I've shot sabot slugs from smoothbore guns. You're better off with a musket, accuracy-wise.

 

[SuA]

Hey everyone, thanks for all the feedback!

Lucky for you, you can go a bit shorter than we can here in the US without a title II tax stamp (18" for shotguns to stay title 1 here).

Strictly speaking, I could go further, as anything with a full length below 60cm (23.6") AND a barrel smaller than 30cm (11.8") simply becomes a 'pistol'. In practise getting a permit for it wouldn't be very easy, but law-wise it doesn' really make a difference.

1) Steel vs Lead. That is a function of the choke rating. Generally, anything full, extra full or super full needs to be steel rated. But if you're lobbing the tube, it'll be cylinder bore, so no worries.

Sounds logical enough. On most shells I know, the pellets wouldn't have exited the cup yet before it leaves the barrel, so I don't see how Steel vs Lead would matter unless the tube narrows (choke).
Wanted to be sure that was universally ok, or that there were things to watch out for.

4) Model. Well, I'd probably avoid the aluminum receiver Ultralites, since it sound like you wanna put this thing through it's paces. There were, of course, models factory made pretty much the way you want yours. I'm not sure when they started chambering them in 3", but it'll be marked.

3" is indeed nice to have, but not really a priority.

I read about the Ultralites alu receiver, and already ruled them out. Partly because in a used gun you can't tell how hard it has been beat up and the fact that chopping the barrel will no doubt cause some extra stress to the receiver.

5) Measurements: That's gonna depend on the model. They may have 3, 4, 5, 6, or 8 round tubes. From the length you're talking about going with the barrel, a 3 round tube is about all that's gonna fit.

As said, the exact length hasn't really been decided yet. I was expecting 4+1 or 5+1, but I never saw any exact measurements and could only base myself off pictures and make guesstimates.

If any of you could measure the tubes (length from the front of the receiver to the front of the mag tube (including the fitment thingy on the barrel, basically the full length of the barrel in the picture attached, starting from the receiver)) for 3+1, 4+1 and 5+1 models? It'd be a great help.

The shotgun in the image looks about perfect for home defense or self defense. Just enough bbl to get beyond the mag tube & no more and a real stock. Handy, handles well, and still usable as a bludgeoning instrument. What's not to like?

And on top of that, esthetics are most pleasing!

Anyhow, it'll mostly see use at the range, for ****s & giggles. Chances of being used for anything else is fairly slim, but you never know. Used for HD at night though? Prepare yourself for massive flash and best wear hearing protection, I guess.

I suspect sabot slugs will not work well in a smooth bore.

Well, since they're made for rifled barrels, that's not really a surprise.

An eighteen inch bbl 37 slug gun is pretty easy to come by, and is a very compact shotgun. I would think rifled sights would be more useable and practical (especially with the traditional high visibility orange triangle front sight factory mounted on them). I have found a number of them (primarily 80s production) to have a bit of a loose leaf sight, which a simple drill and tap for an allen head set screw takes care of.

I'm going for smooth bore, so no rifled slug barrel.

As for the sights? I'm probably going to put something different on it (so I'd prefer getting the shotty without any rear sight on the barrel, not sure how easy that would be to remove). Probably low profile ghost ring sights or express rifle sights, since I'm not a fan of beads on shotties.

Dont worry about the magazine tube wear. All pump guns get it.

I know that extensive wear of that kind (and a sluggish pump) can be caused by a bent part (that I do not know the name of).

Of course, all shotguns will have some wear on the tube eventually.

 

[VA27]

I don't have a 37 on hand right now, but as I recall with a 4+1 (which is what is in the pix you posted) the barrel will be around 14". A very handy size.

Unless you have extremely long arms I'd shorten the length of pull to 12 or 13 inches (with pad or plate, as you prefer) as it makes the gun look a little more balanced.

I am one of the few who prefer rifle (express) sights over the ghost ring. It gives the gun more of a 'vintage' look rather than a 'tech' look.

No worries on steel shot or slugs. I have found that the sabot slugs in a smooth bore don't shoot any better than regular slugs and are an unneeded expense.

If you can start the project with one of the 'Deerslayer' models (smooth bore, rifle sights) you'll be pleased, as the guns were bored specifically for best accuracy with standard Foster-type slugs and better patterns with buckshot. Load it up with your favorite Brenneke slug and it will be awesome!

20 years ago I had an custom Ithaca M37 Stakeout. Pistol grip, 2+1, 10.75" barrel. It was handy for raids and warrant service, but it was an absolute bear to shoot with buckshot and slugs (this was LONG before reduced recoil loads) and merely unpleasant to shoot with birdshot.

Good luck with your project and don't forget to show us when you get it finished.

 

[SuA]

Thanks for the feedback, VA27. I was indeed expecting the 4+1 to be the best fit.
I'll start looking for a suitable shotgun, but no idea when I'll find something that suits my fancy, so don't expect any quick feedback on this.


Also if anyone has the exact measurements asked above for the 3+1, 4+1 & 5+1 models, I'd appreciate it!

 

[Youngster]

Measurement wise, a 13.5" barrel will sit on a 4 shot mag tube flush to the lug like the one pictured.

As an owner of a 12.5" barreled 870 I have to warn that short barrels are very loud and "blasty", they're neat and wonderfully manuverable but I'm not sure I'd want one as a an "only" barrel length.

The Ithaca corncob forends are probably the best looking forends in pump shotgundom but they're somewhat skinny and make it fairly easy to touch a hot barrel, especially in the older models. I have small hands and I still have to watch myself.

Being small in circumference and finished as they are, they're also just a bit slick, so that I would worry just a bit about my pump hand possibly slipping off and getting out in front of a 13" barrel.

 

[Leadhead]

Good project Eurotrash, I'd go an inch or so longer then the one in your picture, (25mm-30mm) for aesthetics alone.

Does anyone know the factory barrel lengths for the Ithaca M37 Stakeout's?

Also what chokes did they come with?

Thanks, LH

 

[SuA]

Measurement wise, a 13.5" barrel will sit on a 4 shot mag tube flush to the lug like the one pictured.

Thanks for the valuable info!

The Ithaca corncob forends are probably the best looking forends in pump shotgundom but they're somewhat skinny and make it fairly easy to touch a hot barrel, especially in the older models. I have small hands and I still have to watch myself.

I'll consider myself warned.

Could put a barrel shroud on the project gun, but I'm not convinced of the usefulness nor of the esthetics.

Being small in circumference and finished as they are, they're also just a bit slick, so that I would worry just a bit about my pump hand possibly slipping off and getting out in front of a 13" barrel.

Especially if it's a model that can slamfire...

Good point.

I'd go an inch or so longer then the one in your picture, (25mm-30mm) for aesthetics alone.

That's about what I had in mind, yeah. Might depend on the type of sights I decide on too. Might make it so that the entire front sight post sits in front of the mag tube. But then again, maybe not.

Does anyone know the factory barrel lengths for the Ithaca M37 Stakeout's?

13 inches (33 cm) from what I've found. Though the company has changed hands so often it's hard to tell all the versions that were made... Plus it being popular means it has been modded A LOT over the decades.

 

[Youngster]

One thing to look out for, on 2 3/4 guns at least, is that the most problematic and critical part, the shell latches, are becoming scarse.

And it seems as if most of the ones that are out there now are coming off of used guns since they haven't been produced for a long time now.

If you get a 2 3/4 gun and the latch goes soft you might be stuck, or at least have to go through extra hassle finding a good replacement.

3" latches are no problem.

 

[SuA]

Since the person aiding me with the conversion is also a CNC machine shop nut, I doubt making a replacement would be an issue (although costly).

I'm hoping to find a 3" that suits my fancy, but 2 3/4" should be plenty to fit my needs.

How can I tell the shell latches are due for replacement on an M37?

 

[Youngster]

They start dumping out a live shell when you slide 'er back, or causing an annoying double feed jam.

 

[SuA]

I know that malfunction (researched it earlier), so that's ok.

I was more hoping for pointers at to how to tell that the shell latches are about to give away.