doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Lengthening 2 9/16" chambers

Hello,

I have a question concerning value of lengthening chambers on an original 16 ga with 2 9/16" to 2.75". I intend to use this gun explicitly for hunting and use RST and Polywad vintagers. Th gun in question is an LC Smith FW. Will longer chambers have any benefits given I will never really have the need to shoot off the shelf mass produced loads?

Thank you,
jmc

I see no benefit to extending the chambers in your gun. If you are shooting 2.5" ammo in it you are already getting any benefit extended chambers might provide...Geo

Thanks George.. I appreciate the perspective as that is exactly why I stick to appropriate loads and if no other net gain, I'm reluctant to remove metal.

Jerry

jmc,
In addition, I'm told , by people that generally don't discourage lengthening chambers, that LC Smith FW barrels are too thin in critical areas to safely extend the chambers. BTW, I'm not an expert in the matter.
Mike

Thoughts here
https://docs.google.com/document/d/1ZIo0y746UsSRZIgRuuxwAbZjSBHitO_EanvwLYc-kGA/edit

Short version. The critical area is the end of the chamber and forcing cone. In heavy barreled turn-of-the-century U.S. maker 12g doubles, the angle of the forcing cone is usually greater than the taper of the exterior of the barrel, so it is not uncommon that the forcing cone WT is the same or greater than the end of the chamber WT. THIS MAY NOT APPLY to small gauge American (nothing special about a Smith FW) or lightweight British doubles.

No reason to do it, I have done it before and wish I had not

Well, this all started with a desire to lengthen forcing cones and open up chokes on a tightly constricted set of FW 16 ga. bbls and work to be done by a knowledgeable Elsie 'smith... I've followed the general logic of pressure vs recoil and, shot deformation impacts on patterns.. I found a nice lightweight and solid gun for grouse/wc and committed to opening up the chokes. The forcing cone request got overshadowed by short chambers which I already address by using appropriate ammunition. Turns out that the work got moved up in the queue overnight and the chambers are now 2.75". Oh well... I just wish more folks would recognize that when it comes to hunting, the extra $5/box for appropriate shells is immaterial when you add it all up. Live and learn...

some say there would be a reduction in recoil resulting from a reduction in peak pressure...if so, that would be better for gun and shooter...

and then there is the pattern uniformity issue...if patterns are not to shooters satisfaction, then lengthening chambers and forcing cones may improve patterns...

Back in the day, when Western Cartridge Co. first brought us high velocity, progressive burning powder loads, and upped the 16-gauge payload to 1 1/8ounce and the 20-gauge to one ounce, they put up their 12- and 20-gauge Super-X loads in their 2 3/4 inch FIELD shell. But, for the 16-gauge Super-X load they went with the "standard" 2 9/16 inch FIELD shell. The 2 3/4 inch 16-gauge shell really started to get some traction when Remington Arms Co., Inc. brought out their Model 11 and "Sportsman" autoloaders in 16-gauge made for 2 3/4 inch shells. While the high velocity, progressive burning powder load, like the Remington Nitro-Express, in the 2 9/16 inch shell was 3 drams equiv. pushing 1 1/8 ounce of shot, for their new autoloaders they introduced their 2 3/4 inch Auto-Express 16-gauge shell with 3 1/4 drams equiv. pushing the 1 1/8 ounce of shot. Winchester had such a load in their July 1931 catalog. I don't have anything Peters between 1932 which doesn't have such a load and 1935 which does. In that they already had it in the Winchester brand, the Olin's didn't get around to adding such a load to their Western Super-X line until 1938.

one ounce loads in 16 ga seem right...if one wants to shoot 1 1/8 ounce of shot, then perhaps its time to switch to a stout 12 bore gun...

Well JMC, I would be considering a law suit against a gunsmith that deepened chambers without express instruction to do so. It ads no benefit, I mean zero, and it removes metal from the most critical area of the barrel. It won't cause harm if the barrel wall was thick enough but no way of knowing that unless it is measured. Getting an accurate measurement right at the end of the forcing cone and just beyond it so as to know exactly how much metal you have to work with is a lot harder than just running a reamer, which any fool can do. Remember that the walls of the chambers on the side that adjoins the other barrel can't be measured. That's a judgment call made by guess work. I can't believe how often people do it, even reputable gunsmiths, without any mention of reproof. I don't think that any reputable British gunsmith would do it without reproof.

I have shot 2 to 3.5" shells and a big ole tom turkey doesn't know the difference when he gets smacked in the head I promise

I can't begin to imagine how many early American doubles with original short chambers have been reamed to 2 3/4". I don't think removing 3/16" of metal at a very, very shallow angle or degree at the front of the chamber is going to hurt anything on a set L C Smith fluid steel barrels. It will slightly reduce recoil and maybe improve patterns a wee bit. Just shoot reasonable loads and you will be fine. No regrets.
JR

Timely topic because two days ago I picked up a 1929 FW-16 that had its chamber lengthened to 2 3/4". I just figured I'd hold it to 1 oz. loads on birds and my usual 7/8 oz. target loads.

Like Stallones, I have done it to a few guns early in my SxS days. Learned better and wish I had not. Live and learn (and hopefully keep all my fingers and eyes).

Lots of good info and perspectives! I rembember the first time I shot my Ithaca NID 16 with 1 1/8 oz of lead and the recoil sucked. I am not overly concerned about stretching the chambers 3/16" as I have no reason to overload... Mr. Roberts has expressed what I understand to be the general consensus pertaining to L.C. Smith fluid steel barrels and I'm comfortable with that. No I'll will or lawsuits but you will have the barrel walls accurately measured at some point so if I ever part with it, the next owner will know where things stand.

-Jerry

No. You live in Virginia so they can just drop a pallet of shells at your doorstep w/o getting a signature for delivery from you. Consider yourself lucky some poor fella from Kalifornistan was asking us at another forum about shipping costs for 55 flats of shells. Apparently real soon ammunition will not be able to be delivered to his doorstep.
Governor election is just around the corner be sure to vote.

Per Sherman Bell's research on long hulls in shorter chambers, simply lengthening the forcing cone without lengthening the chamber will negate much of the pressure increase (which is typically less than 1,000 psi) resulting from the slightly longer hull.

I have a modern British 16ga (Webley & Scott 700) with 2 1/2" chambers. The chambers are factory, but it's obvious that someone had the cones lengthened. I shoot 2 3/4" shells, reloaded to low pressure and with 7/8 oz shot, in that gun. They work well. For heavier hunting loads--and I won't go any heavier than 1 oz anyway--I'll use RST's.

Sorry about the unwarranted chamber work on your Elsie. As others have said it's an old storry and probably no harm done. If you had this helpful video, you could have saved some cash!

https://www.youtube.com/watch?v=amBveFBnVgY

It's nice of you to try to make the OP feel better and I'm sure you are probably right, at least I hope so. Still some issues here though. What you describe is just lengthening the forcing cones not deepening the chamber. No comparison. Reducing recoil? Laws of physics say otherwise. Better patterns? Where is the evidence for this? Sherman Bell's experiments on this subject were very informative but he never mentioned the added strength the shell casing provides to the chamber wall. Not at all negible and where it extends into the forcing cone will also add it's pressure resisting strength to that area.
Any increase in pressure caused by the constriction of the case mouth will be mitigated by the added wall strength.
My main complaint is still the same. People reaming deeper chambers without first measuring and profiling the barrels. In a country with no proof laws. Jesus wept.

Step away from the cliff, Nial. It's all very minimal.
JR

Yes of course. What was I thinking of?

British guns and their delicate nature. Elsies don't need no stinking proof.
JR

"the added strength the shell casing provides to the chamber wall."

Seriously?

Shirley you jest.

Always missing from the internet discussion boards on this topic, is the part where the original poster is (supposed) to say, "I have spent the better part of the last year patterning my (insert brand name of gun, here) with this (type of ammunition, here) and have discovered a problem, that can't be resolved by using (insert different brand or type of ammunition, here).

Why does it always go this way? At no point was it noted by anyone to start there, to see what he had.

To the OP. if your gun ended up with 2 3/4" chambers by accident, that is too bad, but, not insurmountable. It seems your notions of what to use in the gun, for the shooting you do henceforth are sound. A little testing will go a long ways, I assure you. Patterning guns is about as dull a past time activity as one can come up with, but, one that carries huge dividends, later.

I have had exactly one gun that I couldn't get useful patterns with, at typical ranges I shoot at, with ammunition I had on hand. I honestly believe I would have, but, sold the gun before I did.

Carry on.


Best,
Ted

If you're referring to the R-15 20 gauge....don't feel bad. That thing didn't or just couldn't throw decent patterns no matter what shell was used. I spent a lot of time and money trying to unlock that guns secrets, never could get it figured out.

Shirley I do not jest. You tube has many people who delight in making improvised shotguns. Iron pipe slide firing, plastic flare gun modified to handle shot shells, etc, etc. That stuff is tremendous fun. Scope to try all sorts of ideas and find out stuff for yourself. Make a 12 gauge barrel from a piece of PVC pipe. Reinforce with couplings, then turn down the outside diameter until it blows. Informative fun. Every thousand added to wall thickness has an effect. From ignition to projectile clearing the muzzle the intervening space is just a pressure vessel. People have been fooling with this stuff for ages. You, well maybe not you exactly, could figure out the hoop strength of the shotgun chamber. Then figure out the hoop strength of the shell case and add it to the former. At one time there were people who doubted that the Earth was a sphere.

Dustin,
I suspected that gun was among the first that was produced after Paul Bruchet retired for good. The barrel boring machine at Bruchet/ Darne was 2 stories tall, bored the barrels lengthwise, and was something only a very skilled individual should have been close to. That was Paul.
Hindsight is always 20/20, but, I would have liked to have had someone like Stan Baker look at those bores, and get his input.


Best,
Ted

A Cheddite plastic case measures .025" of work hardened plastic.

It might hold 3 BAR. Let's say it will hold 10 BAR (145 PSI).

At a working pressure of 800 BAR, that is (at the very maximum) a percent and a half.

That's lost in the noise of shell to shell variation.

The Earth is an Oblate Spheroid.

It would be simple enough to test.

Find a rubber plug that fits a shell and drill it for an inflation needle, you know, the kind Tom Brady uses to deflate footballs. Hose clamp to open crimp.

Clamp the thing down so the primer can't blow out, and turn on the air compressor.

If it gets to 30 PSI, I would be shocked.

Agree 100%. I too thought the notion of a plastic case adding much more than an iota of wall strength very far-fetched.
JR

If you cannot work out that the earth is flat, how can you work this out ?
O.M

You are right. The earth is an oblate spheroid. I apologize.
Your analysis of the strength of a plastic shot shell is not germane. At 10 BAR it probably would blow out the primer or swell up and split. Inside a gun chamber it will act very differently. An early sign of excessive pressure is a flattened primer. Meaning that the normal primer was retaining it's shape under, let's say 800 BAR. That same primer it it weren't backed up by the breech face would blow out to hell and gone. The same analogy will hold for the case. The only way to test exactly how much hoop strength a case provides is to get two identical single barrel shotguns. Using a standard case in one increase the charge until you get a dimencial change. Now in the other gun, using similar cases but having 1/3 of their circumference removed lengthwise follow the same procedure. I believe there would a significant difference in results. Do you say the difference would only amount to 10 BAR?

I think it would be zero.

The case is ironed by pressure to the chamber walls.

It can't add any hoop strength before the chamber yields because of it's elasticity.

A brass case flows under pressure, you can't tell me it adds any strength to the system.

Yours is the first assertion of this alleged phenomoneon I can recall.

The first assertion is true, so what?
The second, steel is also elastic, so what?
The third, where to begin. Because brass flows under pressure it can't add any strength to the system, really? Do you really think that?
Let's put all that aside for a bit and look at what will happen in two identical pressure vessels in the following test. One is subjected to increasing but time limited pressure spikes until distortion. The other is subjected to the last pressure on the first before distortion and is held at that pressure. Over time the second vessel will distort too. How quickly this happens depends on the material involved. What revelance does this have to the matter at hand? Only to illustrate the difficulty in testing the effects of pressure in different contexts. Submarines are designed to withstand a pressure from the outside that would blow them apart if applied from the inside. But enough. I can see that nothing I might say would convince you. And rightly so too. If I don't back it up with proof-- well.
By the way, can you prove th Earth is an oblate spheroid?

Sure. But it requires a very accurate scale and a good bit of inconvenient and difficult travel.

My Fox Sterlingworth with lengthened chambers AND cones would weigh more at the pole (pick one) than at the equator.

Gravity is inversely proportional to distance you see.

Before we part agreeing to disagree, consider this:

Do you suppose an inner tube ads any strength to the tire?

Hmmm. Going back to the years I worked in a service station and repaired bunches of tires: You can certainly run on a tire with holes if it has an inner tube. But I don't think I'd want to count on the integrity of a shotgun with holes in the chamber walls, counting on the hulls to keep me safe.

What kind of strength? Schwinn actually sold, back in the day, inner tubes that were "thorn resistant".

They were slightly harder to poke a hole in. And less flexible, making the bicycle more work to ride.

It could be argued that the tire/tube assembly, when so equipped was, "stronger" than with the standard tube, could it not?

Best,
Ted

Yes, but wood cracking at rear of side plates is common problem. It maybe more common than found in old Ithaca 37. Most used field grade LCS guns have them to greater or lesser extent. Looks like JMC has that covered by using light game loads. Don't see much reason to ream out chambers because it isn't going to provide anything in return for effort required to do it.

If by strength you mean resistance to internal pressure, then of course, if the inner tube wall is uniform and all else being equal, the tire with the tube will withstand more pressure. That's pretty basic engineering. I beginning to think that you are more interested in appearing clever than in the underlying subject of pressure. Furthermore the subject of gravity is far more complex than you seem to think and you could certainly not determine the shape of the planet by your method. Gravity varies all over the surface of the Earth, lots of research on this by the US Navy. This is my absolute last post on this thread. Having worked for the Navy on nuclear subs I'll bet I spent a hell of a lot more time thinking about pressure than you seem to have done. The End.