I have read that the 7.82 Lazzeroni patriot is on par with the .300 Weatherby Magnum, but it is 12% more efficient using less powder, with lighter recoil, longer barrel life, and lower report. So, a fatter case than the patriot would be even more efficient and so on and so forth. what if a .50 Browning case was cut down to 2.05 inches in length and necked to .308? It could/would be on par with the .300 RUM or bette yet be even faster and flatter than the .300 RUM. Could any of this be feasible/possible? Any information would be much appreciated.

Rock

Rather than cutting down the .50 BMG case, try the .50 Spotter-Tracer case instead. The Spotter-Tracer is much shorter than the .50 BMG cartridge, and was mounted coaxially on another gun. It was used to fire "spotter-tracer" rounds until they were on target, then the main gun would deliver the payload. The Spotter-Tracer cartridge was loaded with a very heavy, very slow bullet with the same trajectory as the main gun. The ST bullet had a primer in the nose to flash and smoke on impact, and would trace for a very long time as well.

Check out this link for a picture of the case:

http://www.biggerhammer.net/manuals/tm43-0001-27.pdf

The Spotter-tracer case is a little longer than the case I would like to use, just necked down, and loads would be roughly 100-110 grs of powder, which is a lttle higher than in the RUM, so this case should offer very high velocity and powder efficiency. But, would the fat case allow the powder to be burned in the case and cut down on throat erosion or no? Any nformation would be much appreciated.

Rock

From what I've read about "modern case design" if the case diameter at the shoulder is more than twice the bore diameter you run into problems.

Also, the case you describe would be so over-bore by the time you worked up a load you would need to rebarrel.

I would say you should cut the .505 Gibbs cartridge down to 2.2,2.4 or something,,and have it necked to .300 or .338 dia. Sounds like a better idea than the behemoth .50 BMG.

The thing to remember is that short and fat is no more effecient than long and skinny. Case CAPACITY is what counts, not shape.

IF the weight of the bullet is the same, and the pressure is the same, capacity equals velocity. PERIOD.

I know, I know, the advertizing gurus are saying it different but I think I'd rather believe the chrony than some office-bound idiot that has NO clue what he's talking about.

I agree with JBelk. I hacde also run both 6mm/284 and 6mm/06 from the same barrels, yes barrels not barrel. Although that was with 1 in12 twist and mainly 70 to 75 grain bullets.

It is true that quite often 22 PPCs at the range are going as fast and even faster than the 22/250 but there is a reason that is unrelated to case shape.

For reasons which completely escape me, poorly bedded rifles and especially with shit barrels seem to shoot OK with backed of loads but not with full pressure loads. Net result is that factory out of the box 22/250s are losing accuracy at much lower pressures than the bench gun in 22 PPC.

Mike

Thanks Jack. In fact in bigger bores straight cases will be a little better, with right
powders.The gunwriters who promote big diameter,
short cases, should know that it takes some energy
to push against more shoulder.

Mikes point about rifle bedding and construction,
is the factor.IE the better it is built , the more
pressure and velocity it can handle while
maintaining accuracy.Ed.

The thing to remember is that short and fat is no more effecient than long and skinny. If this is true, then why can the 7.82 Patriot with 73 grs of powder do what the .300 Weatherby Magnum does with 85 grs of powder?

Lazzeroni cartridges are loaded (and suggested loads for reloading) operate in the pressure area of 65,000 to 67,000 psi range.

Rock--That 73 grains of powder in Lazz case is faster, higher energy powder than the crappy
Norma powder in the Wea case.So they run higher pressures and more total pressure under the curve.

You take both cases,
get the exact capacity measurements, figured at the same powder, bullet, figured at the same
expansion ratio. and put them through the
Quikload or whatever, figuring to the same pressure.You will see what Jack is referring to
in having to compare everything the same.Ed.

The thing to remember is that short and fat is no more effecient than long and skinny. If this is true, then why can the 7.82 Patriot with 73 grs of powder do what the .300 Weatherby Magnum does with 85 grs of powder?

Perhaps the answer lies with the ballistics of the big 308 and big 338 Lazzeronis. Both claim a full 100 f/s over the 30/378 and 338/378 with waht I think is a slightly smaller case capacity. Since the lenght is the same then the Lazzeronis are very slightly thinner than the big Wbys.

If we are going to use different claims then we can reverse things and ask why is the 270 Wby much faster than the 270 WSM?

Another issue to consider in the comparison of any two calibres is powder suitability. A good example is the 375 H&H and especially with spitzer bullets in 270 and 300 grain. In the 375 H&H the 4064 type powders are a bit fast and the 4350 type powders are a bit slow to achieve the full potential of the case capacity. Thus a case a bit smaller or a bit bigger than the 375 H&H will be able to show better velocity in relation to their case capactity. In fact the 375 H&H Improved is a perfect example of this as the increase in capacity brings the 4350 type powders right into play. However if we never had the 4064 and 4350 type powders but instead had one powder that was in between these two powders, then the 375 H&H Improved would do very poorly when compared to the standard H&H.

Mike

I remember reading somewhere that in addition to having higher pressures, Lazzeroni also uses only specially lubricated bullets to increase velocity. Handloading without their bullets, it isn't possible to get the claimed factory velocities, within an acceptable pressure range.

Take a look at the Lazzeroni web-site where John talks about his NP-3 coated bullets....also unless your rifle barrel is 26" you won't get those velocities (for the short magnums) and if you want those velocities for the longer rounds you had better plan on 27" or 28".

If you are really curious about the Lazz cartridges, spend a dime and talk to Mark Bansner. Mark (and his gunsmiths) build as many as anyone (using a variety of actions) and has a lot of experience. He will certainly tell you what you can expect using different rifle components and loading components

Sorry to pop anyone's bubble, but short and fat IS more efficient than long and skinny in cases of equal volume, and this empirically works out to a 6% advantage in energy or a 3% gain in velocity AT EQUAL CHAMBER PRESSURES.

The reason for this is that case volume increases as the square of diameter and linearly with length, so the internal SURFACE AREA of the short fat case is smaller than the long skinny one when volumes are equal. After ignition, the expanding gasses are not merely pressure, but they do WORK on the base of the bullet and all of the internal surfaces of the case. The more surface area, the more heat is lost, and the less energy is available to do work on the bullet base. The advantage dissipates very quickly as the bullet moves down the barrel, so the added velocity occurs in the firsr few inches of barrel.

When comparing a 300 Win Mag to a 300 WSM, with both held to 65,000 psi, the front end of the pressure curve for the WSM is a bit flatter due to energy conservation...the WSM needs 7.2% less powder to achieve the same velocity in equal length barrels when barrel length is measured from the fornt of the chamber. If you scrutinzse the load data, you will see that the WSM needs nearly 72 grs of powder to reach the velocity of the 300 Win Mag with 77 grs.

Now, if we measure bbl length from the base of the chamber and then hold length constant, the WSM gets an extra 1/2 inch of bore to work with, so there is an additional 30 fps advantage to the WSM. Finally, the shot to shot pressure variations are smaller for the short case because of better ignition, allowing the WSM to work safely at higher average pressures. In the end, the WSM needs only 70 grs of powder to duplicate the 300 Win Mag with 77 grs.

This is not worth all the hype, and only an engineer would write home about it, but the effect of short and fat IS there and if Sir Charles Newton was a bench rest shooter, he would not be surprised.

Sabot is absolutely correct. I have been working with a shortened PPC case necked to .17 cal. it has nearly identical case capacities as the .17Rem cartridge yet will surpass.17Rem velocities using less of the same powder in same barrel length's and twists! There are many tests which have been run to support and explain sabots and my point, many of which have been published in P.S. Magazine

[ 06-24-2003, 18:55: Message edited by: TC1 ]

Sabot... I do not think you have a clue as to what you are talking about. Short and Fat cartridges CAN be more effecient, but not for the reasons you have suggested. Thermal dynamics is a very complex science, one that I doubt anyone could *solve* by energy losses or gains in rifle cartidges during combustion, let alone in one particular rifle. One very important feature you left out is the CASE contact area with the SINK (chamber). More important than your AREA calculation is how much actual contact the case is making to the chamber. Also how thick the chamber is and how long the barrel is. Another is the thermal properties of the powder, as I am certain they are not all alike. Individual bores and chambers would far exceed the losses attributable to thermal dynamics.
I strongly suggest you look at Beroulli's Principle of fluid dynamics. Where you have a short fat, necked case, the pressure will drop at the neck but the flow velocity will increase. Energy of the flow will remain the same, at the neck, however, more of the potential energy is turning into kinetic energy through velocity of the powder column. Too much velocity and too little powder obviously wont work, also... not being necked down enough wont work. Fatter with close powder weights to the cartridge you are compairing *should work*. Also... short fat necked cartridges stand to reach and hold a longer maximum pressure due to the fact that they will *see* more back pressure from the combustion column flowing off of their shoulder.
hope that helps

Smallfry -

Thanks for the reply....the application of the Bernoulli principle to the short and fat issue interests me. I understand the principle, but can't figure out why a long cartridge and a short cartridge with the same neck and shoulder dimensions would behave differently when using Bernoulli.

If we set my thermodynamics arguement aside for the moment, and just look at the metric "PSI", we get a less complicated view of how the internal surface area relates tp pressure and efficiency. Note that Pressure per Square Inch describes force per unit area of some container. We take the force in pounds and divide it by internal surface area.

When the area gets smaller we also need to reduce the force to keep PSI constant. This effect is present even when volumes are equal but surface areas are different. The case with less internal surface area needs less force and less propellant than the one with larger surface area to generate the same pressure level...even when volumes are equal.

There is an interesting side-bar article in the latest Guns&Ammo magazine written by John Lazzeroni. In the article he talks about tests he has run with his short-mag Patriot and the 300 WinMag WHEN BOTH ARE LOADED TO THE SAME PRESSURES.

He also states that he knows the WinMag is normally loaded to slightly less pressure than the Patriot.

I don't recall the exact velocities (using 180gr bullets) but ......

when both rifles had 24" barrels the Patriot clearly was faster than the WinMag....

when both rifles had 26" barrels the Patriot was I believe still slightly faster than the WinMag but the difference either way was within differences you would find between any two barrels......

when both rifles had 28" barrels the WinMag now clearly was faster than the Patriot.

I'm assuming John started with 28" barrels and bobbed them for each new test but the article doesn't say.....

[ 06-26-2003, 23:36: Message edited by: DB Bill ]

And DB Bill.... That makes total sense to me. The shorter, fatter powder column will burn hotter and faster, and exit the neck faster because of Burnoulli's Principle. The winchester not only would have a higher velo in a longer barrel, but you should see this difference expand as the projectile weight goes up. Within reason of their respected bearing surfaces.

Out of curiousity DB Bill, the Winchester holds more powder, but by how much?

I guess one easy way for me to explain the Burnoulli's Principle, is a syringe shooting water out, the fatter the syringe the faster the water comes out when the same speeds are applied to the ram. Much like that, in a nut shell.

[ 06-27-2003, 03:05: Message edited by: smallfry ]

smallfry -

The syringe is a good example, and demonstrates to me why Bernoulli's principle won't explain the increased efficiency. The FORCE necessary to push the plunger at the same rate in the short, fat syringe is greater than that in the long thin one...more pressure is needed.

The long thin plunger must move faster than the short fat one in order to expell equal amounts of fluid through the same needle bore (work) in the same time period (energy). If the same force is applied to both plungers, they empty the syringe at the same time, yeilding equal amounts of energy. This is saying that the same pressure level in both syringes will empty them at the same time is they have the same volume.

Now, the syringe does not have to deal with the nasty issue of internal surface area because the cylinder volume decreases as the plunger moves down the chase. In a rifle cartridge, the case volume is constant, with the pressure generated by the propellant.

At the instant of ignition, the expanding gasses exert a FORCE equally on all internal surfaces of the vessel. Since only the bullet moves, it does so. For any rate of bullet acceleration, there must be one and only pressure level - force per unit area - acting on the base of the bullet and this pressure is the same on all internal surfaces of the case as well. When the case internal surface area is smaller a higher proportion of the total force is exerted on the base of the bullet, which has the same area in the long thin and short fat cases, since caliber is constant.

As the bullet moves down the barrel the "effective" chamber is elongated and the advantage of shot and fat dissipates. The advantage exists, for practical purposes, for the first few inches of barrel travel.

As barrel length increases, a long thin case with a larger volume will catch up with and then surpass the velocity from a short fat case capable of duplicating the bigger case's velocity in a shorter barrel. Hence the Lazzeroni findings...

smallfry......according to John Lazzeroni it took 6 or 7 more grains of powder for the WinMag to reach the same pressures as the Patriot.

I think the reason the 300 WinMag gains velocity at a higher rate than the 300 Patriot has more to do with the fact that the extra 6 or 7 grains of powder burned by the WinMag produces more "gas" over a longer period of time than does the powder burned by the Patriot there by taking more advantage of the longer barrel. The way to overcome this is to simply push the Patriot neck forward slightly and sharpen the angle of the shoulder to gain the extra grains of powder.

The question unanswered for me is would the results be similar if )1)you used different powders in each case to reach the appropriate pressure levels, (2) you used different bullets of the same weight, and (3) switching primers.

This is what makes it fun and I really like the short-magnums.

[ 06-27-2003, 08:21: Message edited by: DB Bill ]

DB Bill... This is just speculation on my part but... I think you are right. I believe that the patriot, regardless of what kinda powder it uses, will burn it hotter and thus faster because of the reflected load it *sees*, that is to say... the back pressure. The more "wall" (steep shoulder) it hits the more back pressure is likely to be present, rockets will oftan explode when too much of this phenomene occurs. Luckly rifles are strong, and powder is measured and set afire until a aproximate pressure is reached. These cartridges are trying to show us that they need less at times to achive similar results, and if more important things like... the damn rifle was made strait, the chambers were cut tight, and all barrels were made equal, it would probably be easier for everyone to accept.
The powder column in the win mag is also longer, which no two ways about it will also take longer to burn. For these reasons and the Burnoulli's Principle, I reach my personal opinion on why these cartridges *might* send lighter bullets faster with less or the same amount of powder. The Burnoulli's Principle, by the way is commonly used in all sorts of engineering applications, from moving water through pipes in a power plant, hydraulics, pneumatic machines, to rockets. Looking at your questions I would say...
1) I havent a clue.
2) I havent a clue.
3) I havent a clue.
especialy number two... propellents and how they behave, is far too complex for me. And I am a just a dumb young'n in school .
The bullets too, I know personaly when I change bullets in the same weight with the same charge I can see 50-100-150 fps diff at times. Obviously it would have alot to do with the material, bearing surface, and fit.

These kind of cartridges dont interest me much, but I am sure glad they are around... they have really attracted alot of new shooters.

[ 06-27-2003, 09:26: Message edited by: smallfry ]

smallfry...there is a firearms writer who I really like named Mic McPherson. He is the editor of "Cartridges of the World" and is a regular contributor to Precision Shooting, The Accurate Rifle, Varmint Hunter and Petersen's Rifle Magazine and is an all-around amazing source of information when it comes to rifles and reloading plus I've found a nice guy who is willing to share what he knows....plus he likes short cartridges too.

He's written more than one article about them (as well as developed his own line of extremely short cartridges that he has copywrited) and has some really good explanations why they do so much with less powder and less recoil. Without going into some of the more esoteric things he discusses, several things that stand out......(1) the short powder column allows more of the powder to be ignited by the primer (fast ignition) rather than be contact with other burning powder (slower ignition) when compared to a longer, thinner case and (2) less powder percentage-wise, is in contact with the case which also improves ignition as powder in contact with the case is only heated toward ignition from all sides. This means that more of the powder is actually ignited so less unburned and partially-burned powder is left in the barrel and remember this powder doesn't contribute toward pressure. This unburned and partially-burned powder does however become part of what is called "the ejecta" and adds to the weight of mass being sent down the barrel (the other part of mass is the bullet itself) so this means the less ejecta of the short magnumbs (due to more complete combustion) doesn't contribute as much to recoil as the ejecta from the 300 WinMag (which is heavier in comparison) does.

Smallfry and DB Bill -

Hope I'm not getting on anyone's nerves!

1. I like the ignition arguement as it relates to increased efficiency.

2. With respect to recoil, however, note that the mass of the "ejecta" is the same whether it is powder or gas...the reduced recoil only occures when the short fat case uses less powder to achieve the same velocity.

3. Equal pressure levels in the two syringes will expell fluid at the same rate where the needle bores are the same.

4. The Bernoulli principle explains the acceleration of fluids and gasses passing through nozzles of different diameters, but not the efficiency of short, fat cartridges.

Now, let's take 2 gas cylinders of equal volume and pump air into them until we reach 65,000 psi. The short, fat one has 10% less internal surface area than the long, skinny one. Air is added to each vessel at the same rate.

We are surprised when the short, fat cylinder gets to 65,000 faster than the long thin one. This happens in Dive shops all the time. The cylinder with more surface area has dissipated heat faster than the short fat cylinder, and more air could be put in before reaching 65,000 psi. For fast tank filling, dive shopps will actually put the tanks in trash cans full of water, and the water BOILS of the tanks as they are filled.

Of course the short fat tank eventaully cools the the same temp as the long thin one and in the end both hold the same amount of air at the same temperature and pressure. HOWEVER, when the short cylinder was hotter and had less air in it, it could still do the same work as the long tank if the air was released into an air cannon...the pressures were the same, but heat had given the smaller amount of air more energy.

This is precisely what happens in internal combustion engines. Big bore, short stroke engines are harder to cool than small bore long stroke engines when both have the same displacement and horsepower.

In a rifle case, all of these effects take place, even though we are going from zero to 65,000 psi and back to zero in milliseconds. The dive tank filling took 10 minutes! HOWEVER, these seemingly short milliseconds are eons in the world of high temperature thermodynamics, and the energy loss will be quite proportional to that of the two dive tanks.

When you talk about 10% less surface area in regard I think it is more to the point to realize there is some % less powder in contact with the case with the result that more of the powder gets completely or more completely burned than in the longer case.

An extreme example would be a perfectly round case that would have the max internal volume for the minimum surface area. This is one of the things I believe that moved McPherson to develope his line of very, very short cartridges that are almost half orbs they are so short.

The two practical problems that arise are in making the brass and properly chambering the rifles. I think if you read what Mic has written it will help to understand the process.

Smallfry -

Thanks for indulging me...and I respect a persom that sticks to his GUNS! Especially when they argue logically and respectfully. I really have enjoyed our dialog.

You did catch me in a error, and i fess up...the heat does not migrate out through the case, like the dive tanks. It goes down the barrel and does more work than the long case with the same volume, using the same amount of propellant. To get the same pressure and velocity, the long case needs to have more volume and a higher charge weight.

.

Sabot... yes, I believe that�s correct. Honestly, I have never been an efficiency nut(though at school, engineering sure wants me to ), especially where rifles are concerned. That�s why I shoot a 300 H&H instead of a 7.82 patriot. It is an interesting subject though, one that would require quite a bit of lab work that no doubt would cast even further doubts into our minds .
One of my two favorite efficient cartridges is my 250 savages, and my 22 Khornet. Everything else I have is too old, too slow, too big, too long, or too fast with too much powder to be called efficient. They are my kind of cartridges and are geared for results, and nostalgia.

Smallfry -

I think we have come a long way in this discussion, and narrowed things down.

I am maintaining that the smaller internal surface area, containing a given pressure level, will have the capacity for more work than the larger internal surface area at the same pressure level when both cases have the same volume. Both cases, having the same PSI, do not have the same value P, because PSI is arithmetically P/SI and as SI decreases P increases. A higher total P can do more work than a lower total P.

Okay Sabot, Smallfry, and DB Bill;
This has been interesting reading and I suspect y'all know what you're talking about. But what I want to know is this: can I expect to reach approximately the same velocities with same bullets in the .35-300WSM as are published for the .358 Norma Mag. Of course, side benefits will be doing it in a slightly shorter action (slightly less weight and bolt throw, and a more rigid action for possibly better accuracy) and without that darn belt! What do you each think?
Jerry/AK

Short answer is NO! You will probably get close if you stay with lighter bullets but as you go up to 250gr the wildcat will lag behind. This will be very similar to the differrrences between the 35 Whelan and the 350 RemMag. Would an animal notice the difference....also NO!

Sabot--in comparing my 458 HE to a 460 Wea, they have same capacity within a grain.About 144.
My case has has about 3.65 sg in of sidewall area, and WEA has about 3.35.But with powders suited to my case it out does the WEA by at 2%
at lower peak pressures.10,000 psi
lower. My case is straight belted , and 3.45 in long.We compared them.
So shorter and fatter isn't the best for absolute performance as the formula we developed years ago shows.The other major factor in fat cases is the
a little extra energy is expended against a shoulder, thus not being there for a longer push
against the bullet base.IE with right powders,
you can get more area under the pressure curve, with straight case.Of course in small bores
straight isn't available.Ed.

The 358 WSM is very intresting, and I have one mocked up here on my desk. DB's answer is essentially correct. You will need from 73 to 80 grs H2O of usable case capacity to duplicate the 358 Norma, and it just ain't there in the WSM necked up to 358. You can, however, safely launch a 250 gr bullet at 2700 fps in the 358 WSM, so its a nice round about half way between the 350 Rem Mag and the 358 Norma.

Jerry/AK... I wouldnt worry about the action being more "rigid" for more accuracy, in fact... I dont believe that would be true, there are far more pressing issues to accuracy than action length. If you like short actions just get what you want... a 35-300wsm. If I were to buy a 35 today, I would build a whelan and not worry about anything else.