doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Safe to use 2 3/4" lite loads in 2 1/2" chambers ?

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 2�" 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 2�" 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 2�" 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.