Ithaca 37 Ejection Problems

[Andy]

I'm working on an Ithaca model 37 12 gauge and feel like I have hit a wall, looking for recommendations on how to proceed.

The problem: Budget trap loads do not reliably extract from the chamber & I really want the gun to shoot all types of ammo reliably.

Symptoms: 1 out of every 3-5 rounds sticks in the chamber preventing the action from opening. When the gun is warm from fast shooting the issue is less likely (15 rounds good in a row today when I got it pretty warm, then jams again when cold). I've tried a couple brands with mixed results, they all still have the issue occasionally though. Doesn't happen with older high quality brass base ammo. When I take the barrel off it is difficult to remove the spent hull from the chamber, need to use leverage off my hand with the tip of pliers under the rim.

What I have done so far:
- Cleaned entire action/bolt thoroughly, replaced both extractors and extractor springs with brand new parts from numrich & brownells.
- Checked chamber with this tool from brownells to make sure tight forcing cone isn't causing high pressure & excess base expansion: https://www.brownells.com/gunsmith-tools-supplies/measuring-tools/shotgun-chamber-gauges/shotgun-chamber-gauge-prod593.aspx
- Lightly polished chamber with this 12 gauge chamber flex hone: https://www.brownells.com/gunsmith-tools-supplies/shotgun-tools/barrel-hones-accessories/shotgun-barrel-polishing-flex-hone--prod647.aspx

Took it out today but the issues remain (although improved from when I started).

What do you guys think should be tried next? Is more chamber polishing the next sensible step to take?

Edit: adding some info based on responses below:
- After each of the above "what I have done so far" steps I test fired the gun, issues remained after each one though, but I did try them one at a time to help isolate if something worked.
- Chamber is in great shape no rust or pitting, very very clean, very smooth to the touch & by eye right now
- Only prying cartridges out when necessary using my hand as a leverage point for pair of pliers that only touch the case not the barrel, using extractor notches to avoid touching barrel at all with pliers when doing so.
- I have made sure I'm lining up the extractor grooves well with the extractor so that it isn't binding in that area

Thanks,
Andy

[country gent]

I would recommend another very light polishing and only that if it seems to help try again. with all you did at one time its hard to tell what made the improvement there.If high brass is working then it sounds like the back 3rd of the chamber is where the issue is.

[Jeff Michel]

Sounds like the chamber has pitting near the base of the chamber. You might get another box of shell to try, possibly the lot of brass wasn't sized properly. I would hesitate from doing much polishing (a little is OK) you run the risk of belling the chamber if your excessive or heavy handed. I doubt it's a short chamber, it was good quality shells would be difficult to extract. You might want to also check for burrs near the rim of the chamber, prying anything out of the chamber is not a good practice, use a cleaning rod to knock out the offending hull. Good luck

[NSB]

Some guns are famous for this, the Ithaca 37 is the poster child for this problem. Those budget rounds you're shooting are a steel base with a brass colored finish on them. Your problem will go away if you use ammo with an actual brass base on it.

[rking22]

37s do that, the steel heads do not spring back like brass did, and many cheap loads are a bit spiky pressure wise. I would be sure your barrel is not over rotated or overly tight at the retainer. The extractor groove is only slightly wider than tbe extractor and this will bind the extractor. I have a 1957 16ga that is very picky in that regard. There are still some loads I just dont put in it, they go thru and 870 and get reloaded with lower pressure loads. 16ga hulls are scarce, i wouldnt fool with that for a 12.

[Flailguy]

My Ithaca has problems with winchester shells. Does fine with all others I have tried.

[Texas by God]

Win AA worked in every 37 I've ever owned. Bargain shotgun shells are usually anything but.

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[John Boy]

I have several Ithaca's in different calibers. The only issue extraction cases are the plastic ACTIV's. Other than them, I resize the bases before any of my reloads and NEVER have had any extraction issues with any brand of hulls

Suggestion to determine the extraction issue: Coat a live round with Prussian Blue or a Magic Marker - fire the round and then look on the hull where the scratches are ... even money says on the bases

[Andy]

Thanks guys, I have added on an edit to the original post to address most of the ideas you brought up. Some very good ideas/questions in there I believe I answered them all above with the edit (to try to make it easier for others joining the thread later to follow). Very good idea to try the prussian blue and see where it is binding the most on the hull, I will do that next.

2 guys in my club both have ithaca 37s that are eating the same federal bulk loads with no trouble so I really want to get this one working like theirs do. The person I'm doing it for has free access to federal bulk ammo through a trap program so there is a huge benefit to them if I can get this working with the inexpensive loads.

[Drm50]

I had problems with some of the cheap target loads going under the extractor on single and SxSs.
In both 20 & 12 Guage. These guns are tight and never had trouble with AAs or High Brass. The
problem is the rim on the steel cases. My chambers are in fine shape.

[rking22]

Andy, relative to the other 37s that like the ammo, are they of similar vintage to the problem child? Sometime between 1957 and the early 70s Ithaca made a subtle change to the extraction, At least thats what my reasearch indicated. Also suggested due to my 57 gun being picky and a 70s 20 ga eating anything i stuck in it. Anecdotal, but follows the idea of an improvement.
Maybe consider comparing the problem child to one of the others. Maybe even exchange barrels (asuming interchangable serial range) as a test to narrow possiabilities????
Interested in your results, a s I like 37s but the "single shot" thing is irritating to say the least!

[Texas by God]

The Ithaca 37(Remington17) are the slickest pumps ever IMO but the Rem 870 is my pick.

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[trapper9260]

I have my dad's 37 that it was made that the barrel was made to the gun and what ever i put in it i do not have any problems like stated. The only one I did have was that after you shot the first shot and pump it the 2nr round would go off. But had that fix and it was a bent spring.

[W.R.Buchanan]

Be careful not to tighten the barrel nut too tight, it bends the barrel. Mine just got back from Ithaca after a complete redo only to find it shot 2 feet high at 25 yds.

I was told after they fixed it that bending the barrel was a common problem caused by over-tightening the barrel nut, and then when the gun gets hot it expands and the barrel gets forced up. This will also cause the fired hull to malform under firing and cause the problem you are having. IE stuck hull.

You tighten the nut down until finger tight without using the lever. Then back it off one click.

My gun came out nice and now I have a brand new M37 made in 1940 that is already broken in. It is the slickest pump gun I have ever used.

hope this helps.

Randy

[Rattlesnake Charlie]

I have found the Federal Top Gun in the three and one quarter dram with one and one-eighth loading to be the easiest to extract (drop) out of my cowboy action shotgun. The Winchester usually stick, especially the seven-eighths oz load. A coating of Slide-Dri inside the chambers helps some too.

[Texas by God]

That English stocked Featherlight is gorgeous.

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[2152hq]

Try giving the chamber(and the bore for that matter) a really good scrubbing with something to cut through any plastic residue build-up that may be inside there.
The chamber and bore can appear to be perfectly clean and bright, but can actually have coating of plastic on it from the case/hull and the bore from the plastic wads.

This film is what the fired hull grips on to and makes extraction difficult at times. Some brands of ammo worse than others,,some not effected at all it seems by a build up. The texture of the hull as well as the load when fired seem to have a say in wether they will extract or stick.

Common brake cleaner works well to disolve the plastic build up. There are commercial products on the market made just for this problem too.

Separate the bbl from the rest of the gun when doing this as most any of these solvents will damage wood finish and other non-metalic parts.

Spray/coat the bore and chamber.
Wrap some steel wool, or even fine scotch brite around a used up bore brush on a rod that you can chuck up in an elec drill.
A fairly snug fit in the chamber is good. An extra dose of the solvent on the brush& scrubber pad and have at it in the chamber and bore while spinning the rod in the drill.

You'll be surprised at the crud that emerges from the bore.
Clear it with a wiping rod and repeat as needed.

Try it again in live fire and see if the clean out makes a difference in the extraction of the problem loads.

If you google 'plastic buildup in shotgun chamber' you'll find lots of info and comments on the problem and ways to fix it.
It's a common ailment and it does exactly what you are experiencing.
The tendency for the problem to 'go away' as the bbl heats up is that the plastic fouling becomes soft from the heat of the bbl. Then the rounds don't stick as much anymore but slide more easily off of it.
Cold bbl,,and you are right back to the same problem again.

Might not be the cure all,,but it doesn't take much to give it a try.
Hope you get it worked out.

[Andy]

Thanks again for all the input, I'll try to address each idea/point that was raised:

- I'm not sure on the other two Ithaca date ranges, I'll have to check next time I see those guys. This one is a 1975 if that sheds any light on things.
- I didn't know about the potential to bend the barrel by over tightening, this one doesn't have a lever in that location just a knurled cap in good shape so I can't imagine anyone could have reefed on it too hard though, good to know however.
- Thanks for the thoughts & info on the plastic buildup, I've definitely polished the chamber very well so I don't think any of that could be left in there at this point, tried bronze wool & some JB bore paste on a rotating brush before going with the flex hone. It did have some build-up initially but just bare metal looking now.

Further info from today: chamber measures .815" just inside the breech and .799" at 2.75" in. According to the SAAMI chart (link below) I'm as large as allowed at the opening (.810 +.05 correct?) and just over minimum at 2.75" (.798+.005). Am I reading all that right? I'm not solid on exactly how to read these drawings.

I had hoped it would be on the tight side of the chamber spec at the base and that would give me room to polish it a little wider, but looks like I don't have anywhere to go at this point. Any/all thoughts appreciated.

12 gauge 2.75" saami chart on page 18 here: http://saami.org/specifications_and_information/publications/download/Z299-2_ANSI-SAAMI_Shotshell.pdf#page=8

[rking22]

Yes your dims are correct, tolerance should be .005, so .815 is max. Does the base area of a fired case show a buldge just ahead of the extractor hook?
A 75 vintage gun should be after the extractor update, thats about the time of the 20 I had. Really curious how your barrel would behave on a frame that shoots them ok. 800000, serials and later have freely interchanagable barrels, 75 is for sure in that range. If their barrel is serial numbered then that gun is not. That would seperate the issue between barrel/chamber and extractor/ bolt. Then you could focus on a single area. Puzzled, a 75 12 ga should be easier to feed. That said I had a full size 20ga 870 that would NOT, no way extract anything with a higher base than a AA! Well if you slammed the but on the ground it did but that really didnt work well on doubles. Polished chamber,,ect,ect. Didnt like it well enough to keep it, so sold it to a friend with an extra skeet barrel. Ran like a top with his barrel!

[RU shooter]

The Ithaca 37(Remington17) are the slickest pumps ever IMO but the Rem 870 is my pick.

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Amen! I've got a 17A 20 ga and it's like an ice cube on glass .

[Andy]

Thanks rKing for dimension confirmation. No visible bulges in base forward of extractor hook

Do I understand right that you're saying that my barrel should interchange with anyone whose gun is 800000 or higher serial? And that if the barrel itself has a serial # then it isn't compatible with this receiver? Our of curiosity & for my learning's sake, what makes them not interchangeable, is it a mechanical fit/obvious issue or something more subtle where the wrong barrel would fit but not work well?

Any way to tell if this barrel on the gun was the barrel that came with the gun from the factory?

I might have a chance to try some barrel swaps with the other guys, that's a good idea to try to 100% isolate things. The shell sticks so hard in there with the barrel off the gun that I feel like it has to be chamber/ammo related though. Not wanting to take the chamber past SAAMI spec it may be time to admit defeat and say it's a gun that will always be picky on ammo, hate to do that though.

[2152hq]

If you have access to a finish chamber reamer,, by hand take the reamer and run it into the chamber with proper lube and remove any extra matr'l in the chamber.
If it's a factory spec reamer,,it'll leave you with a factory spec chamber.

It'll recut (or just trace) the forcing cone and the rim recess as well.
Any out of wack areas will be trimmed to spec. You'll not be harming anything by doing this as the reamer is factory spec.
Metal removal will be next to nothing,,swarf on the reamer will amt to some fine curls of steel most likely in a couple areas. But you may find an undersized area or two, maybe even the rim recess.
The chamber length may be a bit short and the forcing cone a little rough. Some shells run a tad longer, some shorter than the labled 2 3/4".
A long one unfolded into a slightly short chamber or the beginning of a rough forcing cone can grab as well.

Also, that plastic fouling can't easily be removed with simple cleaning and brushing techniques. If it could, then there would never be the problem in the first place.
A solvent is needed to disolve and cut through it in most instances to really get it out of there.
Stainless steel brushes, oil & steel wood and all that will simply brush over it.

The early M37 bbls had threads that were not universally timed during their production. The threads didn't start at the exact same position on every bbl.
(The frame threads were indexed to start in the same position on each frame however).

Each of these early bbls had to be fitted to it's frame individually. This was done before the forend lug was silverbrazed into position, not knowing where that 6'oclock position for the lug was to fall.
The bbl was numbered to the frame at the time it was fitted, then sent on it's way for the lug fitment, extractor cut, bbl markings, polishing ect. The ser# on it allowed the correct bbl to be reunited with it's frame when done.

To avoid the hand fitting and extra handling involved, Ithaca changed the process and began the universal fit bbl's. This simply indexed the threads on the bbls to a start point that matched the frame so any bbl when placed in any frame would fit & headspace correctly.

In the older frame/bbl combinations,,you can take an un#'d bbl or one with the wrong ser# and drop it into the frame and turn it in and draw it up tight with the TD screw.
All will seem just fine. They look OK, The action works,,
But the headspace can and in most instances be off, sometimes grossly off spec.
That was the reason the bbl was hand fitted on those to begin with.

I worked in a shop in the 90's that used to specialize in taking universal fit M37 bbls and reworking the threads so that they were a hand fit replacement bbl for the older Model 37's that used those fitted bbl's.
It involved TIG welding the threads and some complicated lathe work (at least from my standpoint!) by one of the resident cranky olde gunsmiths to get the NOS M37 bbl converted to a handfitted replacement for a customers vintage Model37.

[rking22]

Above is the whole story, great post! If your bbl has no serial number and your frame is 1975, then it fits and headspace should be fine, baring a factory defect. I like the idea of a chamber reamer, that would cleanip any issue, just dont cut additional headspace. My 16 ga tolerates cheap stuff with a good rim, hates stuff with a marginal rim. I have seen refetence to a "fix" but cant remember the details. Maybe 2152hq has insight thete????

[Jkrem]

My Dad has a 16 ga Ithaca model 37 gun made in the late 1950s. He bought it new, and he said it always fed great with 2-3/4 and 2-1/2” paper shells, but that he could never find a plastic shell that wouldn’t jam. Never hunted with it again, switched to his L.C. Smith.

[wv109323]

Will the gun cycle rounds without firing them? This would determine if the firing is expanding the hull causing difficult extraction.

[Andy]

Thanks for the detailed post 2152, lots of great info in there.

I really think the chamber must be free of any plastic residue at this point. I see just bare metal in there and can clearly see scratch patterns change in the metal from before/after when i polished it, so I suppose I could be wrong but I really don't see any evidence of plastic fouling in the chamber. I have also cleaned multiple times with shooter's choice and given it plenty of good scrubbing time with brushes, and denatured alcohol swabs after polishing, repeat over a couple sessions.

Very great info on the barrels, that is very useful to me thanks for passing on all that info.

A chamber reamer would be a good final option to try out, I have checked the forcing cone distance with the brownells gauge but that doesn't check for anything in the chamber other than that, so it is possible that a reamer would catch something.

The gun will cycle unfired rounds just fine and just to give more explanation on my earlier info I've run a whole box of 25 winchester AA (all brass bases) through it without a hiccup, as well as 6-10 old peters all brass. When using the all brass loads extractions is much more effortless of a pull on the slide (even compared to when the cheap loads do extract somewhat normally) A couple different brands of steel based loads all had problems to different degrees, with the federal top gun being the one I tested the most as it is the objective of this work to get it working with that specific brand/line of ammo.

So, I feel reasonably confident to say that this issue is related to some feature that is different between winchester AA trap loads and federal top gun trap loads. I speculate it is the brass bases contracting more after firing like many others have already mentioned, but I ought to measure a few fired cases today to get some actual data on that.

Thanks again for all the helpful input from everyone, even if I can't solve the issue I've already learned a lot.

[W.R.Buchanan]

That English stocked Featherlight is gorgeous.

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I paid $100 for that gun in 1973 it sat in my safe for many years until I finally got back to it. I bought the wood from Fajen in 1976 but never finished fitting it. A friend finished it and checkered it and it came out nice.

Ithaca completely reblued it and all the choke tubes for the Cutts Compensator, and replaced a couple of internal parts.

I showed it to the friend I bought it from as it was his fathers gun originally, and he offered me $1500 for it on the spot. I really like the gun so he won't be getting it back any time soon.

Randy

[Andy]

Little bit more info:

Metal diameter measurements on shells fired in this gun after all work was complete, measurement taken on flat part of the metal head closest to the plastic of the hull.

Winchester AA all brass head .808"
Federal top gun steel head .814"

Correction to an earlier post, I put a magnet to some old peters shells that ran fine in the gun and they were also brass-washed steel surprisingly (definitely not just the primer, whole head was magnetic). I don't have any left to measure the fired diameter of, perhaps it is just really small, thin steel heads that are the problem, not all steel headed shells?