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winchester 97 chamber size

Discussion in 'Shotguns' started by porsche, Sep 4, 2008.

  1. porsche

    porsche Well-Known Member

    i have a model 97 built in 1898. could the chamber be other than 2 3/4"?
  2. SASS#23149

    SASS#23149 Well-Known Member

    Yes,it could be.

    sorry,that is all I know,but I have read that many times about model 97's.
  3. rcmodel

    rcmodel Member in memoriam

  4. ReloaderFred

    ReloaderFred Well-Known Member


    Your 1897 chamber is going to be 2 5/8". In order to shoot 2 3/4" shells with star crimps, you're going to have to have it rechambered. Even the guns marked 2 3/4" on the barrels were made for the old roll crimped shells, and are about 1/8" too short. The shells will fit and fire, but when the star crimp opens up, the plastic is protuding into the forcing cone, restricting it. This increases pressure dramatically and will crack the frame.

    I suggest finding a gunsmith familiar with shotguns and have him drop a chamber gauge into your gun. You'll know right away if it's chambered too short for modern shells.

    Hope this helps.

  5. kirbythegunsmith

    kirbythegunsmith Well-Known Member


    Some clarification is in order.
    The barrels from Winchester of classic era had plenty of barrels on 97's that had no chamber length markings, but measure the same as those barrels WITH 2-3/4" markings.
    For instance: every Model 37 12 ga. is a 2-3/4" marked barrel, but measures as a nominal 2-5/8" or 2.6"
    A pair of Model 12 16 ga. barrels marked 2-3/4" that measure at about 2.6"
    A pair of '97 barrels with patent marks of 1900 and 1901 measure the same as an "E" model, about 2.6"

    The only typical problem vs. paper/ plastic hulls is in the port configuration on M-12's, for instance, not wanting to clear a more stubborn star crimp end of a plastic hull.

    Was there going to be necessity to mark a barrel already proofed for the most modern length shell available at the time (2-3/4")? The 3" magnums didn't come out till much later, and that is when all new barrels would have been prudent to mark.

    Realize that every one of those barrels would have been proofed by Winchester and claimed by them to be safe at the time of manufacture. If they are marked 2-3/4, they should be considered safe. If they measure the same as one marked 2-3/4, they should be considered safe, regardless of lack of marking.
    See that proof mark on the barrel? Every factory marked Winchester barrel will have one. That barrel and the gun are safe. A mechanical check of the safety and locking parts of the mechanism are more important than chamber length precision.

    Those chamber lengths, regardless of whether marked or unmarked, being within 1/8" of a full 2-3/4", have no significant pressure change compared to any other chamber that is at 2-3/4", and are not in any way a danger to the frame or shooter. Period.

    I don't discourage lengthening forcing cones for better patterns, if done the way that I do them, but chamber lengthening is not something I would push by fear-mongering.

    Any tale of a short chamber causing extreme pressure is something I had once believed myself, but no longer.
    Any '97 frame cracking is NOT caused by a measly 1/8" of chamber. NO way, no how.

    I don't see how anybody could make that claim (honestly) if they had no idea of the history of the gun- once owned by an amateur reloader, for instance.

    Reloading with wrong powder/charge MAY do something to the safety factor, but even the more fear-mongered example of shooting 3" shells in a 2-3/4" chambered barrel does not make the 3" shell have any significant boost of pressure with a bit of the crimp laying in the forcing cone.
    The 2-3/4 barrel may not have been proofed for 3" load pressure which is slightly higher than 2-3/4 proof, so don't say that I am saying 2-3/4 barrels are OK for 3" shells. I am saying the individual shell does not get a lot higher pressure from a different chamber length.

    EVERY manufacturer and SAAMI will tell you that you are to shoot how the barrel is marked and no longer than that.
    You should not expect them to tell you that shooting a longer shell is not a huge safety issue. Problems may arise when shooting a long 3" shell in an old loose and wobbly single shot, but that was foolhardy to use even with target loads.

    Did you ever wonder how a gun got to be so loose? It must have been shot well past the slight wiggle stage, and still didn't take off somebody's face. The barrel is still intact and not ruptured.
    Do you think that guns are really that easy to damage, with a tiny shell/chamber length difference?

    Guns, like many mechanical contrivances, are over-built for a safety factor. Recognize that link chains, for instance, have a working load about 20-25% of breaking load.

    You will also notice that I do not take into account any good or bad influence of a pattern with the shell being slightly longer than the chamber since this discourse is about safety.

    Winchester had a '97 taken off the assembly line and put into ammo testing service for well over 20 years and a definite million plus shells. They wanted to test pattern performance on a well-shot barrel, and that one still rated in a passing level for the full choke that it was marked, so, so much for shooting out a choke with lead shot. I'm sure that gun and barrel saw many high brass hunting and buckshot loads.

    I have spent much time conversing with personnel at Remington, from the last ammo plant manager, to corporate higher-ups, to the gun plant service manager. That guy has been Remington his whole career, and some of that time was in the testing area.
    That is where they don't see if a gun is hurt by a load, they find the load that blows the gun apart. Repeatedly. Talking to him is the next best thing to seeing the exploded residue for myself.
    When he says that pressure readings don't spike due to short chamber/long shell interference, that is a fact.

    There are enough circumstances that can make shooting a gun potentially hazardous without keeping another old wive's tale alive.

    Don't take a measurement of a chamber gauge being off 1/8" to get into a panic. I would not expect to use that as a money maker by playing on someone's fears. I do not mind a proper and exact chamber length, but shotguns are a lot different than rifles and throating conditions.
    Perfection is a great thing to have, and I will make things precise for somebody wanting that. I'm not going to exaggerate to get somebody worried enough to have something changed.

    If anybody pushes you to change one of these barrel examples for a safety reason by claiming a slightly short chamber is a grenade waiting to happen, ask them where their research lab is located or what other evidence they have.

    Damascus barrels blowing up from smokeless powder is another one of those old tales, at least from the time when both barrel types were in production.
    The loaders of the day could get bulk or dense smokeless powder.
    Bulk powder used the same powder dipper as the black powder, but the dense powder used a tiny powder dipper. What happens when they get mixed up? Triple charge?
    That must be the fault of the barrel, right?
    If you ever saw the test of a load of various damascus and fluid steel barrels being loaded to destruction, you would not think damascus was weak, any more.
    Some examples had so much powder and shot (well over 4 ounces for some, I believe) that the barrel was filled about half way. Some of the examples had actually welded the shot into a plug that failed to exit, and all the powder gas vented out of the fuse touch-hole. No ruptured barrel, in some instances, even at that extreme. Some of the best rated were damascus.
    I need to dig out the Double Gun Journal with that article inside.

  6. rcmodel

    rcmodel Member in memoriam

    The problem is not that properly made Damascus was inherently weak.

    The problem is that any gun you find today with Damascus barrels is nearing 100 years old or more.
    And a great many of them were of questionable quality to start with.

    And the first 50 years or more of it's life was spent shooting black powder & corrosive primers.

    As a result, most all of them are pitted to some extent, and the pits may have worked their way deeply into the seams of the Damascus steel.

    There is no way of knowing how deeply, or to what extent those old barrels have been weakened.

    The other thing is, smokeless powder pressure spikes further down the barrel then the black-powder most of them were proofed with.

    The ones I have seen that let go, did so right about the forearm wood where your left hand is.
    That usually resulted in the loss of a finger or two, or three.

    It's just not worth the risk!

    I do agree that firing 2 3/4" shells in a short chamber is not nearly as serious as many folks think it is.

    Reliable pressure tests I have seen indicate there is no serious pressure spike, and the short chamber is really no more serious then the shot charge hitting the choke constriction.

    Still, if you have a short chambered gun, it is a good idea to have the chamber reamed out to modern specs just for peace of mind.

  7. MCMXI

    MCMXI Well-Known Member

    kirbythegunsmith, the issue here is FATIGUE which occurs at pressures significantly below the yield strength of steel. The forcing cone on my shotgun was very short and the chamber measured about 2-9/16". The short forcing cone is less forgiving than a long forcing cone so some restriction would definitely have occurred. I'd much rather pay $85 to have the chamber and forcing cone lengthened rather than hope that cracks don't start to appear after a few thousand rounds.

    From Brownell's website ...

    the gun will slowly, but surely, be battered to pieces.

    ... that's what this is all about.

    Any time part of the fired shotgun case enters the forcing cone and creates the “bottle neck” effect, the balance is changed and several detrimental effects occur.

    First, the momentary slowing of the shot charge by the “bottle
    neck” increases the rate of burning of the powder which results
    in increased chamber pressure. In some cases, it is about the
    same as firing a proof load shell. This excess pressure not only puts a strain on the gun’s mechanism and barrel, but also increases the amount of recoil. Provided the mechanism is capable of safely withstanding the 10% to 25% increase in chamber pressure, the gun will slowly, but surely, be battered to pieces.

    The second effect is that as the shot is forced through the “bottle neck”, individual pellets become deformed and out of round. When the deformed pellets leave the barrel, they will not stay with the main charge as air pressure against the deformed pellets causes them to veer away from the mass of shot. The end result is a poorer pattern, both in percent and distribution of the pellets in the pattern circle.While this has been an extreme example, it illustrates the necessity of the chamber length correctly matching the length of the fired shotgun shell. Any time a portion of the fired shell case enters the forcing cone, it decreases the efficiency of the barrel and consequently, the efficiency of the shotgun’s performance.

    Last edited: Sep 5, 2008
  8. ReloaderFred

    ReloaderFred Well-Known Member

    While I don't have a ballistics lab, and don't claim to be an expert, I do have a little experience with the Model 97 Winchester shotgun. I attend at least two SASS matches per month on a pretty regular basis. At those matches, there are approximately 75 to 100 Model 97's between them. I've never seen a barrel blown up, but I've seen several guns with cracked frames, and all of them had original chambers. (These guns are where the extra parts come from to keep the solid guns running.) I've never seen one that had been rechambered that had a cracked frame.

    We're talking about guns that in some cases are over 100 years old, and at the youngest are still over 50 years old. My wife's gun is 109 years old, and there's no way I would allow her to shoot shells through it that are too long for the chamber, which is why I had it rechambered and the forcing cone lengthened, even though it's a solid frame gun and was more difficult to rechamber.

    These old guns in the takedown version also need to be checked for looseness between the barrel and frame. There is an adjustment built into these guns and it needs to be periodically checked. If loose, it needs to be tightened by moving the toothed adjustment in the barrel portion. The two pieces need to be snug when put together.

    Hope this helps.

  9. MCMXI

    MCMXI Well-Known Member

    kirbythegunsmith, that "measly" 1/8" you refer to could reduce the bore by as much as 2.25 times!! With a very short forcing cone, the elongating shell has no where to go but towards the center of the barrel. If the bore is 3/4" diameter to start with, but now you have 1/8" protruding into it in all directions, your bore is now 1/2" in diameter. That means the cross-sectional area of the bore is only 44.4% of the original area. Personally, I believe that this COULD cause an increase in pressure and with repeated firing could lead to a fatigue failure. A longer forcing cone would help, but if you're going to do that you might as well have the chamber reamed to the proper length. As I said, cheap insurance for $85 and which of the two chambers and forcing cones (shown below) would you rather have if you plan on shooting thousands of rounds of 2-3/4"? The first with a chamber of 2-9/16" and a short 1/8" forcing cone or the second with a 2-3/4" chamber and a 1" forcing cone bearing in mind that no one here is going to replace your shotgun IF you ruin it.
    Last edited: Jan 24, 2009

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