Is it safe to use 2 3/4" lite loads in 2 1/2" chambers ?

Barrels are in fine shape, no pitting with min wall diameters of R.023 and L.027 9" from the muzzle.

With the availability of great 2 1/2 inch shot shells online, why would you use anything other than what the gun was designed for........?..........

I think it is wrong to use anything larger than the ammunition the gun was designed for no matter what Sherman Bell says.......other opinions around here will vary........

Here's two ammo companies that supply new "off the shelf" 2.5" low pressure loads for vintage shotguns to folks that don't reload........and one of them is almost in your back yard......

http://polywad.com/

http://www.rstshells.com/store/

I reload all my own and always stay below 7,000 PSI for my older 2.5" guns and use the same 2.5" ammo in my newer 2.75" guns as well......2.5" in 12,16 and 20 gauge guns......birds don't seem to know what they've been shot with, they just drop dead.....

You're going to follow the advice of some guy on the internet? Dude read the box. Does it state the loads are okay in chambers that are 1/4" shorter?

Teeny, you need better info about your gun than the bore diameter 9" from the muzzle.
Length of the cartridge is not as important as the charge within
The proof of the gun is more important than the diameter of the bore 9" from the muzzle

Do you really think he meant he meant bore diameters, with numbers like .023 and .027? Really?

Since he never used the word "bore", I'm gonna take a stab in the dark and say he meant wall thickness, not diameter. And wall thickness is VERY important when pressures are concerned.

SRH

In my opinion yes and no - I own some 2 1/2 12 gauges that I believe this practice is safe in, and some that I do not believe it is safe to do so. It depends greatly on the Chamber Dimensions of the gun, and other factors.

It involves some level of risk, so I can't recommend the practice, you must make an informed opinion and decide for yourself.

Hi all, my 2c worth. I think Teeny ment wall thickness, I also agree with the other posters. The fact is I use 2 1/2" in most of my guns that are chambered for 2 3/4" either modern or vintage and I don't see any difference when shooting wild birds, they fall just as dead with 2 1/2" as they do with 2 3/4".

It's better to be safe than sorry, so I would recommend in sticking to low pressure 2 1/2" shells.

Good Luck!!!!

Greg

Thank you all for proper
direction !

Great forum !

I do not believe using 2 3/4 shells in a 2 1/2 chamber is wise. It may not blow up the gun so could perhaps be called safe, but it has to raise pressure as the shot and wad column are restricted for a very short span of time. Without a means of taking pressure readings one can't know how much it is raising pressure. I use what the gun is chambered for.

I instrumented a 2 1/2 chamber and shot my chosen 2 3/4 load in it. Pressures we're below the load data in the manual. Ymmv.

Several issues at work here:

1. What's the definition of "lite loads"? Most would characterize a 7/8 oz load, regardless of hull length, as "light" in a 12ga gun--but it might not be light in terms of pressure. Or it might be.

2. What's the definition of "the ammunition the gun was designed for"? I have several boxes of British shotshells, some of them 2 1/2", some 2 3/4". The information on the shell boxes tells me that the 2 1/2" shells are appropriate for guns with 65mm/2 1/2" chambers or longer and marked 3 tons. However, the Brits didn't start marking their guns with the "tons" marks until 1954, which leaves it open to question whether guns manufactured prior to 1954 were designed to handle those shells.

3. What we do know, from Sherman Bell's tests as published in Double Gun Journal, is that using hulls slightly longer than the chamber in question does raise peak pressure somewhat. Usually only a few hundred psi, although in some cases a bit more than 1,000 psi.

4. What we also know is that the Brits themselves, for quite some time, have used factory ammunition loaded in hulls that are slightly longer than the chambers in question--without raising pressures to dangerous levels.

My own conclusion from all of the above: IF you know what you're doing and IF your gun is in sound condition, there will probably be no problems using standard 2 3/4" hulls reloaded to the pressures for which the gun was designed--and building in a "safety cushion" to compensate, just in case the longer hull does increase pressure somewhat--in guns with 2 1/2" chambers. The most common exception is in older (pre-1900) guns with very short and sharply-tapered forcing cones. With those guns, there have been reports of even factory British ammo in slightly longer hulls causing problems, such as blown ends on the shells. In those guns, you do need to stick with true 2 1/2" hulls, whether factory or reloaded. But in all the short-chambered guns I've owned, I've yet to encounter that problem. And like Chuck, I reload 2 3/4" hulls to appropriately low pressures and shoot them in my 2 1/2" guns.

What L. Brown said.
One other personal observation; it does feel to me that 2 3/4" shells in a 2 1/2" chamber raise recoil levels a little. Even with identical payloads and velocity. Maybe its just me, but I do notice it.

The data from many tests indicates that there is only a slight increase in pressure(100-500psi) from using the 2 3/4 " loads. I have never noticed any increase in my 2 1/2 guns.

Teeny, what shotgun do you have?

Quite aside from safety concerns, I found that a 2 1/2" chambered gun patterned poorly with 2 3/4" shells. Whether this was the result of shell length may be impossible to know, but it nudged me to use ammo of appropriate length.

Patterning the difference between the two is an interesting question. I will try that and check the difference. FYI,I always shoot ammo with less that 7000psi in my older doubles.

Stan, I missed the wall in his description of his measurement. I still think teeny needs to delve deeper into the best methods for appraising barrel integrity. Even a wall thickness measurement 9" from the muzzle isn't that relevant.

Stallones, you state "the results of many tests" show there is only a slight increase. What tests, where can we see the results?

Also you said you never noticed any increase in your 2 1/2" guns. Were these guns equipped with pressure sensors or how would you notice any increase in your guns?

Stephen Grant side lever & Charles Boswell 2 1/2 " both proofed for nitro

Steel barrels

Nice guns,teeny.

Thank you !

Very extensive testing was done on this subject in England with the introduction of the fold (Pie) crimp shell. This was reported on in depth by Burrard in his book "The Modern Shotgun". The result was that virtually all British shells marked for 2½" chambered guns from that day forward & closed with a fold crimp have been longer than their nominal length.
Most British shooters of this era were not reloaders & bought their shells as loaded for their guns. It is quite possible not many of them were in fact aware the hulls were indeed longer than their chambers, Therefore they seemed to have no problems with either excess pressures, excess recoil or poor patterns.
But let the Cat out of the Bag, Then Kattie Bar the Door!!
For whatever reason Bell was not willing to accept the work which had been settled for some 50 years or so & had to "Do it Himself". His work perhaps brought it to the attantion of a few people who were unaware, but in reality to the extewnsive testing hich had proceded him he was was inventing a solid rubber tire while we already had the Steel Belted Radial. Shells being fired in chambers of a slightly shorter length than their fired length than their chambers is a proven safe practise as long as the shells are loaded to the appropriate pressure level.
The one big Caveat which was mentioned by Burrard which no-one seeems to mention is that shells should not be fired in a chamber shorter than their "Loaded Length". This results in the mouth of the loaded shell being forced into the cone of the chamber, in effect increasing the resistence to the opening of the crimp. Very few 12ga guns will be found actually having 2½" chambers, the majoprity being from 2 9/16" (65mm) to 2 5/8" (67mm). The loaded 2 3/4" (70mm) fold crimped shell measures about 2 3/8" (60MM) long. There is ample clearence between the end of the shell & the start of the cone for the crimp to open unrestricted. There is thus little likelhood of an actual increase in max pressure, but perhaps a slight slowing of the drop from peak. I personally have serious doubts that Bell recorded enough data to postively establish much of anything as absolute fact. It is noted though that he did not come upon anything which disputed that which was already established & had been in practise for years, which apparently he was unaware of.

I've been very satisfied with my 2 3/4 load over the years and have never had any issues with the pattern or anything else. The paper Federal hulls seem to be short lived. But 3 loads are the norm. Velocity of 1150@ 6500 ish psi for 1 oz. I just change shot size for different game. If I can't kill it with this load I don't wanna kill it.

By the time Bell did his tests--which were focused not on Burrard's work, but on the fact that ammo makers continued to print warnings on their shell boxes about not firing longer shells in shorter chambers, thus causing those who hadn't read Burrard (or, more recently, Gough Thomas) to believe that the danger lies in hull length rather than pressure--we had different hulls, different wads, and different powders (in other words, significant changes in shotshells) since "The Modern Shotgun" was published. Reinventing the wheel? Well, perhaps . . . except radials weren't around in Burrard's day.

I am firmly convinced that most of the guns I have seen with cracks in the wood in the head of the stock and just beyond were damaged by heavy loads in short chambers. Most were 16 ga. Some that were drillings were 9x72 as measured, but 9.3x72 as labeled for some reason, and then cracks were certain over time. I don't worry about exploding an action, but do about the woodwork, and the action going loose due to higher pressures. I suspect the higher pressures set up a different vibration pattern, barrel whip and the whole nine yards. Have I shot them that way--I've done every bad practice you can imagine back in the day, but I either didn't know any better, or listened to bad advice. Would I abuse a gun knowing, now? No possible way! Just my 2 cents. Steve

Sherman Bell uses some pretty sophisticated pressure measuring equipment. I'm not sure that Burrard measured anything. I'm not sure, either, of Larry Brown's statement that some of the pressure differences in light loads in two different chamber lengths with 2 3/4" shells exceeded 1000 pounds per square inch. I'll have to read the article again to confirm, but the testing and the article's conclusions lead me to be very comfortable shooting 2 3/4" light loads in my 2 1/2" chambered British game guns.

Eightbore, Bell had one load that showed an increase of 1216 psi when fired in the short chambered test gun. There were other increases fairly close to 1,000 psi: 909, 895, 891.

Burrard did very litle testing of his own outside of pattern testing. What he did was report on tests conducted by some of the major testing facilities available in england of his day. Prior to the final revision of his book quite extensive reports of testing done with Piezo Electric instrumentation was given. It is quite worthy of note that more modern equipment has verified the accuracy of these well conducted tests from the past. There will of course always remain the difference in pressure readings of those taken with crushers & those taking by the PE tranducers. As I recall most of Bell's testing was done with strain gages. Any of the three methods can give reliable & beneficial results, but not necessarily directly equivelent to the others. Only the tranducers as I understand it give a direct & exact reading of the pressure inside the bbl.
Personally I am not questioning the equipment used by either. Simple fact is the testing done by the British with the introduction of the fold crimp shell was far & away more extensive than that done by Bell. What I question is whether he in fact did extensive enough testing to actually isolate thos 1,000+ pressures as to be caused by the hull used or whether other factors were involved. In any pressure testing there will always be variable readings. I do also recall that he tested some of his "Low Presssure" 3" shells in a nominal 2½" chambered gun. If I recall correctly these loads did increase the pressures by some 1,000+ pressure units, what ever units he was reading. This is to be expected as in this case the crimp of the shell is actually being pushed into the cone prior to firing, a factor Burrard Strongly discouraged. I will take Burrards recommnedation here anytime as this practise definitely increases the resistance to the opening of the crimp.
I forget the name now but I once read a balistician for a major ammunition co make the statement that he could vary the pressure reading over a wide range with no change at all to the load except to the crimap applied. the tighter the crimp, the higher the pressure. Shells should "ABSOLUTELY" not be fired in which the loaded length of the shell is pushed into the forcing cone.

1/4" into the forcing cone is 1/4" pushed into an area that is very close to bore diameter. It is also 1/4" of thin plastic, not 1/4" of thick virgin paper shell. Considering that American factorys routinely cut chambers 1/8" short on purpose, to seal the load, I think the 1/4" is a non issue as proven by Sherman Bell. I think we all know that this Greener and Burrard research is just so much bs compared to what we have available today. Let's face it, Greener participated in the "my gun penetrates more than yours does" bull. We all know that was just advertising as was just about all other ballistics conclusions of the day. Sherman Bell has nothing to sell.

Could not agree more with your take.

Couple additional points:

Prior to the advent of the plastic hull and wad, some American manufacturers intentionally short-chambered their guns so that the paper hulls would open into the forcing cone--the idea being that the hull mouth would give some protection to the shot on its initial contact with the barrel. Pattern tests did indeed show improvement with the use of slightly longer shells in short chambers.

As for Greener and Burrard, while the former did have something to sell (guns), I don't believe that Burrard did.

Re pressure increases from Bell's tests: All 4 of the increases to which I referred above--one of 1,000+ psi, the other 3 in the 900 psi range--came from 2 3/4" hulls fired in a test gun with a 2 1/2" chamber. The very hot 3" load Bell tested--near SAAMI max pressure--only resulted in an increase of about 700 psi when fired in the 2 1/2" chambered test gun.

Roy Dunlap's book "Gunsmithing" has minimum chamber & Maximum Shell dimensions for the common shotshells in use at the time of publication (Copyright dates of 1950 & 1963, 2nd edition). I presume these to be SAAMI Specs, but he does not positively state their source. For the 2 3/4" 12ga minimum dia at end of chamber is given as .798" to a point 2.6136" from the breech face. Note this is a bit shorter than the 2.625 of a 2 5/8" chamber. A minimum dia of .764 is given in the cone at 2.8079" from the breech, or about .05" beyond 2 3/4". For the shells a max length is given for roll crimp shells of 2.53" & for folded crimp of 2.41. A max fired length is given for both of 2.760" Note that the max loaded length of either crimp type does not reach the forcing cone allowing unrestricted opening of the crimp. "THIS IS IMPORTANT". Note also that all other gauges have the minimum chamber length at least equal to the nominal shell length, only the 2 3/4" 12ga shows a shorter chamber.
To the best of my knowledge both Bell & Burrard had the same thing to sell, their writing. As stated in my previous post though most of Burrards reporting on this issue was of tests carried out by the British Ammo trade who did have something to sell. This however is not necessarily bad. Remember also when we are speaking of the British their shells had to meet the approval of the proof houses, so yes they had to test a new concept prior to placing it on the market.
Right or wrong the top wad got blamed for "Bad Patterns". With the switch to the fold crimp the British shotshell makers were immediatly faced with two problems. 1st bulk powders were still quite popular there & to put the normal load into a hull now having reduced capacity due to the extra length taken up by the crimp made it diffucult to have an efficient wad column. 2nd the shorter overall length of the hull could be quite easily mastaken for a 2" shell once removed from its original box.
The result was they began experimenting with putting the normal load in a longer case which would have about the same overall length when loaded. It was not at that point in time desirable to lengthen the chambers as this would have required proofing for the heavier load of the regular 2 3/4" shell. "VERY" extensive tests were performed & it was determined that when the proper load was put up in the longer hull no problems resulted from the practise. These tests began in the late 1930s were interuppted by WWII & were definitely finished by the end of the 1940s. The pratise of putting a proper load for the gun in a hull slightly longer than its chamber has thus been well established for more than 60 Years. Anyone can accept it or not as they choose, but it does require ignoring a lot of "Facts".
As to US guns I believe it was mostly Trap shooters who desired the 1/8" short chambers in their guns. It was not a universal practise among US gunmakers to habitually chamber their guns 1/8" short of the noted shell length, but some did, at least for 2 3/4" shells. As during this ers I believe the majority of US Trap shooters preferred the 2 3/4" shell & as most gunmakers of the era would chamber guns to order those desiring to use 2 3/4" shells in a 2 5/8" chamber could have simply ordered their gun so chambered if this was not the practise of the desired gunmaker.
I do recall Bell testing 3" shells in a 2½" chamber just to see what would happen should he leave one in his pocket & accidently insert it into one of his 2½" chambered guns. The load did raise the pressure a good bit but he decided it would not result in a catastrophy. The load however was a very light one for a 3" shell, so much so in fact it made one wonder why he bothered with the longer hull to begin with. I apparently missed the issue in which he tested 3" laods near SAAMI max in a 2½" chamber. I personally would try My Hardest to keep a 3" shell loaded to Near SAAMI out of any 2½" gun I have or should acquire, even if it wasn't likely to actually "Blow it UP".

If I had a nice 2 1/2" Gun, with good lock up n good bbl thickness
I'd handload some light 7/8ths or 1oz,low psi loads n shoot them.
I remember Bell being surprised at how little the thick waxed paper did to raise the psi on some.I think I'd use plastic.
I'd figure the service pressure ,then find a really low recipe to allow for the odd 1000+ psi spike, & then some for luck.
I say that, but if I actually had a 2 1/2" Gun, I might be a little more cautious
be safe lads
PS...wouldn't roll crimped 2 3/4 loads be the answer???
franc

Bell also found that simply lengthening the forcing cone, without lengthening the chamber, usually resulted in some reduction of pressure.

Shoot em...I have been for years..

teeny 350,
This issue is reviewed in detail on pages,260-262 0f Gough Thomas[G.T.Garwood] Gun Book.We read that experiments conducted in conjunction with Eley showed that for a given shell charge intended for use in a gun chambered and proof tested as a 2 1/2,increasing the case length from 2 1/2 to 2 3/4 did not result any significant difference in breech pressure.
At one time Eley sold a shell called the Maximum.This shell contained 1 3/16 ozs; of shot and was safe to use in guns proof tested at 2 1/2 chambers. Perhaps lapogus could comment on its current availability?
As suggested by others use only shells designed for use in 2 1/2 chambered guns[ie; do not exceed allowable breech pressure using home loads] stay safe!

Interestingly, the reason for the article Gough Thomas published on longer shells in short chambers were that some of his readers reasoned such loads would have to be real "pipsqueaks" because of the additional pressure coming from the longer hull. The Eley tests showed that both velocity and pressure remained the same, whether the 2 3/4" shells in question were fired in 2 1/2" or 2 3/4" chambers.

"NO"!!
The load for a nominal 2½" roll crimp shell will ordinarily fit the 2 3/4" fold crimp shell with little adjustment needed. The fold crimp 2 3/" shell has a shorter loaded length than a roll crimp one giving more room for the crimp to open without resistence from the cone. This clearence is essential to the use of the longer hull.
This was what was done by Eley & other British makers years ago, as first reported on by Burrard & later by Gough Thomas.
This is essentially what Bell did also so many years later.
The key is, as well put in Roy's last post, the Load must be appropriate for the gun. None of this should ever be taken as a blanket endorsement for firing any & all 2 3/4" shells in a short chambered gun.

Spot on! American factory 2 3/4" shells are loaded to a higher pressure standard than that for which short-chambered guns--British, European, or older American--were built to handle. But for cautious reloaders, it is not difficult--especially in 12ga--to work up loads which are well within the pressure standards for which short chambered guns were designed.

Another thank you to all who responded !

This forum is an amazing resource.

Kind Regards,
Teeny350

My take on all this is that a 1/4 " longer shell is not the deal breaker. The pressure may or may not rise due to the 1/4" shorter chamber. But from Bell's data I'd allow/account for 15% over if your pressure data is from a 2 3/4" chamber. My data is direct. So I'm confident Im safe for my load. YMMV

Well as I am now in the states for a while with my old 1885 P Webley with a Jones underlever (so a strong lockup there) I will have to check some soft loads out, maybe cheap dove from mart-wal will do the trick.
It has to be less dangerous than working in Juarez.
Regards
Martin

A Stephen Grant sidelever and you have a guy who sells 2 1/2 " shells nearby !! Why ??, best, Mike

Those cheap dove loads are loaded with enough pressure to cycle an improperly maintained 400 dollar autoloader. They have to be, or they wouldn't sell at WalMart. They are almost certainly well above 10,000 psi, far above what I would feed a damascus Grant or Boswell.

I have a close friend who owns what was once a beautiful cased damascus Charles Boswell with the right chamber blown out from using loads with too high pressure. Yes, I warned him beforehand, but he didn't heed my warnings.

SRH

Agree with Stan. "Light" by WalMart standards does not mean low pressure.

Agreed. I read this thread and I keep asking why????

As recommended, I've just placed an order with RST for 6 flats of 2 1/2" 12 ga.

Thanks again to all !

Thank the Lord teeny, that side lever will go on for another 80 years best

Hi 2 Piper,
By "Roll crimp 2 3/4" I meant as a reloading thing,not factory. Like taking a fired 2 3/4" pie crimped shells,cutting the open shell to 2 1/2", load it n roll crimp it.I've never trimmed or even roll crimped a shell before, just curious if this would work crimp wise..with the roll being applied to a formerly pie crimped shell.
Its prolly still dumb, I just wanted to at least be dumb with the right facts, ha ha
cheers
franc

Franc;
I am following what you mean now. I have not actually tried that so not positive if you could get a good roll crimp with whats left of the folds or not. Another option that was discussed a good bit some time back but haven't seen t mentioned lately is the "Hardin" crimp. For this you cut the 2 3/4" hull down to proper length then load as normal a load of proper intensity from a 2 3/4" menu. Then place a top wad on & run through the regular fold crimp stations. Supposedly this will make a secure crimp with a big hole in the center. quicker & easier than applying the roll with no extra tooling required except for cuttin the hulls.

The Hardin crimp works great. Doesn't look very neat but other than that it holds the shot solidly and is sooooo much faster than a regular roll crimp. Sorta fun to do.

Dang - I discovered the "Hardin" crimp on my own - I called it the Half-Assed crimp