Slam Fire Documentation

Moderator: ripjack13

User avatar
.270 WIN
Posts: 136
Joined: Tue Nov 22, 2011 2:37 am
Location: Hampshire, UK
PostPosted: Mon May 23, 2016 2:19 pm
Dear All,

Does anyone know of any *documented* thinking behind the decision to add the extra sear to enable the M37's slam fire facility? I want to know what the designed intent was for the feature.

Thanks.

Regards,

Mark.
Came late in life to shooting but is making up for lost time...
User avatar
Vendor
Posts: 967
Joined: Fri Sep 09, 2011 5:06 am
Location: Mobile, AL
PostPosted: Thu May 26, 2016 4:44 pm
Well, the slam fire feature goes all the way back to the Winchester 97. With all of the moving parts needed to make a 97 work properly, I can't imagine it was an accident. It probably came about because they were going to law enforcement and military, but that is conjecture. There is no record I know that explains the rationale behind it. John Browning had his reasons.
--Jim
User avatar
.270 WIN
Posts: 136
Joined: Tue Nov 22, 2011 2:37 am
Location: Hampshire, UK
PostPosted: Thu May 26, 2016 11:38 pm
ravengunsmith wrote:I can't imagine it was an accident.

Obviously not. (I see a lot of posts on the web sayin' that M37s slamfire because they don't have a disconnector...)
It probably came about because they were going to law enforcement and military

Indeed. I reckon that most people would say that it's so that trenches could be cleared, or whatever. I think that this theory may be wrong or, at least, that there's a more "useful" reason for it.
but that is conjecture.

My theory is also conjecture, of course. :)
There is no record I know that explains the rationale behind it.

Funnily enough, I've never seen anyone even *ask* whether the rational was documented anywhere.

Regards,

Mark.
Came late in life to shooting but is making up for lost time...
User avatar
.270 WIN
Posts: 412
Joined: Thu Feb 23, 2012 5:21 pm
Location: phila pa
PostPosted: Fri May 27, 2016 7:42 am
I don't get the impression it was intentional
more likely a side effect
a side effect the military took advantage of

one of the reasons I think this is,is because they "fixed" it
there is no law I know of that said add a disconnect.
User avatar
.270 WIN
Posts: 136
Joined: Tue Nov 22, 2011 2:37 am
Location: Hampshire, UK
PostPosted: Sat May 28, 2016 1:23 am
twistedoak wrote:I don't get the impression it was intentional
more likely a side effect
a side effect the military took advantage of

Sorry, I'm a bit confused, here. We're talking about an M37 where there are extra parts added to *make* it slam-fire. There's an extra sear operated off of the slide stop that engages with a stub on the hammer.

one of the reasons I think this is,is because they "fixed" it

I have a 1975 M37 which has been "fixed" by removing the hammer's stub. Funnily enough, my two early 1980s military DSPS guns both retain their extra parts.

I *do*, however, think that slam-fire was aimed at LEO and military users. My theory, though, is that it's aimed at preventing issues when under duress rather than "trench clearing" use.

Regards,

Mark.
Last edited by ChAoS on Sat May 28, 2016 10:09 am, edited 2 times in total.
Came late in life to shooting but is making up for lost time...
User avatar
.270 WIN
Posts: 412
Joined: Thu Feb 23, 2012 5:21 pm
Location: phila pa
PostPosted: Sat May 28, 2016 7:57 am
as said it was a carry over of a john browning design that Ithaca adopted
if Ithaca had their way it would be a m33 were talking about ,but patents held it till 37.
brownings designs that the 37 were based off of were done at a point in 1914 which predated wwI s start date. it wasn't manufactured till long after in 1922.
being how browning was pretty much obsessed with autos, the slam fire ability in his designs doesn't surprise me. the 1911 was designed 3 years before the rem 17 and the browning automatic rifle was 4 years after.

so what was ithacas intentions ?
well if it works don't fix it sums up ithacas position to me.
now if you want to ask about brownings intentions?
that's a different story

.270 WIN
Posts: 209
Joined: Wed Dec 19, 2012 12:26 pm
PostPosted: Sat May 28, 2016 9:36 am
John Browning used to work for Winchester and they designed the first auto rifles. 1903 (22cal.) 1905 (32 and 35 cal) 1907 (351 cal) 1910 401 (cal) Then Browning had a tiff over Winchester wanting to make an auto shotgun and told Winchester that he held the patents on the design and left the company to start his own. Winchester decided to go ahead and do their own, but soon found out that the little toggle that opens the bolt to load the first shell was a Browning patent. They then knurled the end of the barrel so you would have to pull down on the spring loaded barrel to load, often placing the butt end on the ground and if those old paper shells got stuck or your hand slipped the gun would go off. The gun was called the 1911 but knick named "The widow maker" Interesting guns. Thanks Donald.
User avatar
.270 WIN
Posts: 136
Joined: Tue Nov 22, 2011 2:37 am
Location: Hampshire, UK
PostPosted: Sat May 28, 2016 10:24 am
So how far back does the "extra sear" design go? For example, did the 1897 have it? If not, when did it appear and it what gun?

Every time I read about the slam-firing ability of shotguns, someone always seems to chime in and claim that it's the lack of a disconnector that's to blame.

But, at some point in the development of the guns leading up to the M37, someone, somewhere said, "hey guys, let's add extra parts to *make* it slam-fire".

What I wanted to know was, what they hoped to achieve. (As I've already hinted, I think that the reason might have been something more than a desire to clear trenches.)

Regards,

Mark.
Came late in life to shooting but is making up for lost time...
User avatar
Vendor
Posts: 967
Joined: Fri Sep 09, 2011 5:06 am
Location: Mobile, AL
PostPosted: Sat May 28, 2016 4:58 pm
The 97 has it, as does the 12. I own both and they have plenty of moving parts and safety features to keep the gun from having accidents with misfiring shells while the gun bolt was unlocked, I still have to wonder if it was intentional
--Jim
User avatar
.270 WIN
Posts: 168
Joined: Fri Oct 23, 2015 2:14 am
Location: Mitcham, South London, England
PostPosted: Sat May 28, 2016 5:15 pm
A shot in the dark, so to speak, perhaps to achieve, with a manual action, (known reliability) parity in respect of rates of fire with the emerging self- loaders.....?

It was definitely intentional, no-one in their right mind would add and work metal accidentally!

The "lack of disconnecter" theorists possibly don't realise that if the hammer were to follow the bolt into battery, it would ride the rear lower corner of the bolt and have no inertia left with which to strike the firing pin (well that's my theory anyway)
User avatar
.270 WIN
Posts: 136
Joined: Tue Nov 22, 2011 2:37 am
Location: Hampshire, UK
PostPosted: Sun Jul 03, 2016 12:12 pm
ravengunsmith wrote:I still have to wonder if it was intentional

And *I* still can't understand how adding extra parts - that could do nothing except release the hammer when the slide locked up - could be *un*intentional. On the other hand, it could be that "trench-clearing mode" *is* a side effect of what I think the aim really was.

impala59 wrote:A shot in the dark, so to speak, perhaps to achieve, with a manual action, (known reliability) parity in respect of rates of fire with the emerging self- loaders.....?

I don't think so.

I've used my M37 for several years now, nearly always for PSG. I *did* have a "serious" go at trying to engage steels in "slam-fire" mode and, with a bit of practice, I reckon that it *could* be done. However, it's not as easy as one would expect.

No, I reckon that the *real* justification was *much* more important...

Even shootin' nothing more serious than PSG, I know that a little pressure (nothing but a running timer, in this case) can make one "go to pot". You end up making mistakes. I can think of few things that'd apply more pressure than being in a gunfight. In a gunfight, there's not much more important than your gun going "bang!" when you expect it to. And *that's* what I think the extra sear is for.

So, let's set a scenario: you want to cycle the action - maybe after a shot has been fired or to take the gun from "cruiser ready" - in order to fire a shot. What happens if you squeeze the trigger *slightly* too early, before the bolt is in battery?

On a "normal" gun, as I understand it, for whatever reason you will *not* get a round fired. I do *have* pumpers that are *not* Ithacas, but I rarely use them, so I'm not that familiar with what actually happens. I don't know whether the action will be free (for you to rack in a new round) or whether you just have to let go of the trigger and pull it again. Either way, any sort of problem is *not* going to help matters.

However, if you're using an Ithaca with two sears, it doesn't matter; if the hammer is cocked, when you push the forend forwards, no matter *what* order you do things in, you'll get the expected "bang!". Now, to me, that seems a *much* better system in a gun intended for military use.

So, waddya fink of m'theory? Does it make sense to y'all?

Regards,

Mark.

P.S. Sorry, guys - I seem to have been a bit tardy with my reply...
Came late in life to shooting but is making up for lost time...
User avatar
.270 WIN
Posts: 412
Joined: Thu Feb 23, 2012 5:21 pm
Location: phila pa
PostPosted: Sun Jul 03, 2016 2:56 pm
still not convinced slam fire was military driven.
I still think it was somehow a cog in brownings automatic and semi automatic gun design evolution.

think about it,,,
with the exception of the manually driven slide the is nothing to prevent a 37 from being full auto.
if you mechanized the slide action it would be classified full auto
User avatar
.270 WIN
Posts: 412
Joined: Thu Feb 23, 2012 5:21 pm
Location: phila pa
PostPosted: Sun Jul 03, 2016 10:26 pm
on a side note
after thinking this over I picked up my 41R that is slam fire capable
and my 82 ultra fleatherlight that cannot slam fire.

the difference between the 2 as we know it the disconnector .it mechanically keeps the hammer from being cocked, and there is a difference between that and keeping the hammer from being released.
I bring thing up because the result is having to rack the slide ,ejecting an unfired shell and loading a new one in without needing to manually press the slide release vs the ability to release the trigger and then squeeze it again to fire is a key point

nothing really new,,

then I got to thinking and took my 41R ,depressed the slide stop and pulled the trigger ,click!
now i'm not dumb enough to try it , but I can pretty much figure out what will happen if I fired the gun without the bolt being locked down by the slide stop.
the recoil will force the bolt and boltslide back into the receiver ejecting the shell.

there is half of the full auto cycle.i'm willing to bet if you put the right kind of coil spring between your forend slide and the receiver body you could get a full auto cycle.
either that or the gun explodes. and in either scenario I don't think the gun will last long

I don't recommend trying it ,and the act of doing it in my mind would be scary as hell
User avatar
.270 WIN
Posts: 136
Joined: Tue Nov 22, 2011 2:37 am
Location: Hampshire, UK
PostPosted: Mon Jul 04, 2016 12:05 am
twistedoak wrote:and my 82 ultra fleatherlight that cannot slam fire.

the difference between the 2 as we know it the disconnector

Can I just confirm what you're saying, here?

You have an M37 Ultralight, made in 1982, that has a *disconnector*? Is that right? (I have to come clean here - I've no idea what a disconnector would look like...)

As I may have said, my 1975 M37's hammer stub has been removed (or never been fitted - I must take a closer look at the side of that hammer the next time that I get it out of the cabinet) to stop it slam-firing. I've never looked close enough at the trigger pack to see if anything *else* changed in the later guns.

Regards,

Mark.
Came late in life to shooting but is making up for lost time...
User avatar
.270 WIN
Posts: 412
Joined: Thu Feb 23, 2012 5:21 pm
Location: phila pa
PostPosted: Mon Jul 04, 2016 8:38 am
the "stub" was removed and iirc the slide stop was altered to pevent the hammer from locking
aka disconnecting it
User avatar
.270 WIN
Posts: 168
Joined: Fri Oct 23, 2015 2:14 am
Location: Mitcham, South London, England
PostPosted: Mon Sep 25, 2017 9:34 am
2nd Attempt here, first was wiped out during submission?
This has been a subject that has bugged me for a time now and so after a little research I now present what I feel is a definitive answer (maybe setting myself up for a fall there)
Firstly some (I won't call them facts as am sure to be reprimanded!) information, relevant to the subject

There are three different types of trigger for the model 37, the slam fire, the standard and the fire interrupter. The slam fire dates from the beginning 1937 up to circa 1975 and so may be also called the Original. The standard, introduced in around 1975 until current and the fire interrupter introduced around 1976 predominantly for LE use. I am somewhat vague with dates as production used up old parts and items on the shelf in stores were sometimes modified. Also the Ithaca Gun Co. was famous for oddities during production
1 Slam Fire (Original) trigger. When a shot is fired and the trigger held back during the reload cycle, the next round will fire as the bolt goes into battery, the slide will trip the hammer sear. If the trigger is released during the action cycle, the hammer will remain in the down/back position until the trigger is pulled again
2 Standard trigger. When a shot is fired and the trigger is held back during the cycle the hammer will not be retained by the sear and will follow or ride the bolt back into battery, it will have insufficient inertia to hit the firing pin and so will sit in the up/forward position behind a live round and the gun will not fire until the trigger is released and the action cycled again (live round ejected) If the trigger is released during the reload cycle the gun will fire as normal as the hammer will be retained by the sear awaiting another trigger pull.
3 Fire Interrupter trigger. When a shot is fired and the trigger is held back, the hammer will be retained by a second sear, and, as the action is cycled and another round loaded releasing and pulling the trigger will fire the next shot. Again, if the trigger is released during the action cycle, the second sear is redundant and the normal sear takes effect.

The Model 37 was developed from the Remington Model 17 and shares most of that guns design and features (JM Browning designed) In the early thirties Ithaca were looking at developing a pump gun and also seriously looked at the Winchester. How history could have been different! In the end patent expiry and the offer of manufacturing equipment from Remington (who had discontinued the M17 and were developing the M31) pointed the way. Now both of these potentials would 'slam fire', not as a feature but simply that was the way the mechanism worked.

The Model 37 has the fewest internal parts of any pump action shotgun, it is this simplicity that has seen the gun through the last 80 years.

Our grandfathers never saw the "danger of death" motto on every item that they purchased as we do today. They used common sense particularly with firearms. The so called 'slam fire ' was normal on many guns at that time.
Today, litigation is king and we are treated as though we cannot think for ourselves or take responsibility for our actions.

The military use of shot guns goes back way beyond the scope of this post, so I shall confine myself to the famous WW1 German demand for the banning of the trench gun (the also slam firing Winchester 1897) as a vile weapon when used by the doughboys for clearing trenches. How much worse than grenades, poison gas and artillery I can't imagine. One can imagine slamming your pump for all you were worth to clear a trench. The M37 was used in WW2 but it seems to have been most popular in Vietnam as a Platoon point weapon, where, using 00 buck, 72 9mm lead projectiles could be fired into the jungle in a few seconds using the slam fire. Additionally, a duck bill spreader was developed to improve the sideways spread. This formidable weapon was unsurpassed in this role.
I believe that US military trainers would take into account the performance and features of any given weapon and train their users appropriately, maybe some of the Veterans on this forum would know for sure and feel able to comment.

With Law Enforcement the issue is a little different. A LE officer who, using a slam fire trigger model 37 in a stressful situation, may keep his/her finger pressed on the trigger during an engagement or firefight and may well then encounter an Accidental/Negligent Discharge during the course of his or her duty. This, of course, the lawyers would jump all over. Like wise, using a standard trigger M37 in the same situation could find the officer with a dead gun in his or her hands with potentially fatal consequences. So was developed the 'fire interrupter' trigger which prevents both of these situations, albeit at the cost of some of the great simplicity of the M37 design.

For sportsmen, hunters, wing shooters, clay busters, IPSC competitors and the like, any of the triggers will be as usable and safe as any other. With a sound knowledge of your gun (and shouldn't we all have that as a matter of course?) all of these triggers are safe. I should mention here that early guns that are worn should not be slam fired as there is a possibility of the hammer striking before the bolt is locked, any gunsmith or the Ithaca Gun Co. itself would be able to check and rectify. I do not know if the 'Fire interrupter' trigger is available from the Gun Co., it is mainly LE but was apparently offered as an option to the civilian market. Over this side of the pond, most things Ithaca are rare and very few LE guns have made the crossing!

To finish I have satisfied myself that I understand how things were and are now, we all know that our M37's will always be referred to as that 'slam fire gun' I just think that we have firearms with a little more history than most and maybe that's why they seem to have more character than most.
The above is my opinion only and quoted information is from a number of publications, primarily the excellent books by Walter Snyder and by examination of my collection and also those of some of my shooting pals. If I have wrongly quoted anything regarding US Military or LE practice then I am happy to stand corrected

The original question from Mark (ChAoS) was about why have slam fire? I believe that in a different age it was simply why not? This was a tried and tested mechanism and, the gun would always fire and not fail when called upon, for defence or putting food on the table. All this achieved simply with few parts and the genius of JMB. Any documentation would be on the standard and fire interrupter trigger as these are the modifications from the original.

Return to Ithaca Model 37

Who is online

Users browsing this forum: No registered users and 2 guests