Home Forums Hunting & Shooting Ask The Gunwriters Short Fat Vs. Long Thin???

Let's say you have a real short/fat cartridge vs. a real thin/long cartridge. From a pure ballistics view which is better given the same bullet weight and amount of powder?


I would think that bullet diameter plays into this pretty big!!!

My friend Charlie Sisk did an experiment with this several years ago, partly at my suggestion. We'd found that the .300 WSM and .300 H&H had just about exactly the same powder capacity with the same bullet seated to standard cartridge OAL.

Charlie first chambered a full-diameter Lilja barrel to .300 H&H and shot 150- and 180-grain handloads with three different powders in his indoor range, chronographing and pressure testing each load.

Then he cut the rear of the barrel off slightly and rechambered it to .300 WSM, leaving the same length of barrel in front of the chamber. He shot the SAME powder charges and bullets. Accuracy, velocity and pressure was basically the same, though obviously with some individual variation in loads.

Aside from case shape having almost no effect, the most interesting thing to me was that the same powder was most accurate overall, whether the barrel was chambered for .300 H&H or .300 WSM.

So it seems that action length and how well the cartridge feeds is more of an issue.


Thanx John !!!

I realize that you wanted to make the conditions the same by using the same barrel and action.Do you think there would have been different results using two different actions with different make barrels the same length????? Say a Remington long action with a Krieger barrel and a Winchester short action with a PacNor barrel.How about the chambers cut by different make reamers??????Wish I had a bazzillion dollars to try all this stuff!!!!!!

Different barrels could have different results with the same cartridge. It would be impossible to garner in useful info with all of the variables that different barrels would induce

If you start changing a bunch of variables at once, you have don't have an experiment any more. Of course there would be different results if you changed a bunch of stuff, and you would have learned absolutely nothing.

It would take me some time to go through my library (using that term loosely), but I recall an article that is similar to the test that John is describing. A well known benchrest gunsmith took a BR gun that was chambered for a cartridge based off the .222 Rem family of cases (might have been a .222 or maybe a 6x47), then he rechambered it for a PPC based case, doing everything possible to ensure that things remained the same from the leade forward. He found the opposite of the null result that John is reporting--accuracy of rechambered barrel was noticeably better.

I think the BR world is the best test bed in the world for accuracy experimentation, and the dominance of the PPC case shape cannot be disputed. The extent to which it is transferable into hunting applications is up for discussion, but anyone who says case shape has no effect is ignoring a significant body of experience by arguably the looniest shooters of all.

One of the benefits that many bench rest shooters extoll about the short, fat cases is that the rifle can have a shorter, hence stiffer and theoretically more accurate action. Sisk's experiment would not take this into account since the same long action used for the H&H was also used for the short WSM cartridge, if I am reading correctly. Maybe not a ballistic advantage but perhaps a platform advantage.

I have a 7mm saum and a 270. Pretty close the same effect on deer. the next time I go elk hunting I'm taking the 7mm saum, because the rifle weighs less.

Most of their testing is in machine rest guns; the action stiffness is eliminated.

I believe Charlie Sisk conducted the experience the sensible way. By introducing additional variables such as actions and barrels, the experiment would have generated tarnished results open to interpretation and challenge.

A comparison between just 2 items offers something, adding more than that is a dogs breakfast and would prove nothing.

JW

I get the same velocity out of a 300 WSM vs a 300 Win mag with 4-5 grains less of the same powder and the same bullets in the same length barrel.

What I remember about the Sisk test that JB was talking about is that he custom chambered the H&H throat so that the bullets had the same jump to the lands as the WSM chamber did - please correct me if I remember this wrong.

The reason I remembered this is that I have have another 300 WSM that has a longer throat - a Sako. It doesn't get as high of velocities with the same bullets and powders as a couple other shorter throated WSM's do. So I suspect that the tight throats you normally see on WSM's is one of the reasons that they get higher velocities with less powder.

I also have a Sako 270 WSM with a longer throat. It gets lower velocities than a couple of my other 270 WSMs with the same powder, bullets etc.. I don't own a corresponing 270 Weatherby mag to compare a long/thin vs Short/fat thing and of course the 270 Weatherby is going to have a long freebore unless you do a custom chamber.

But in the end if you go to the store and buy an off the shelf 300 WSM and if you somehow found a 300 H&H the 300 WSM will probably get the same velocity with less powder unless the 300 H&H has a custom throat that matches the WSM.

Maybe JB can correct me if I'm wrong about this...................DJ

Charlie chambered the .300 WSM chamber with the standard throat, which is almost nothing. He ran the reamer into the .300 H&H chamber just enough to clean up the .300 throat.

I wonder if there are any advatages to the short case for reduced loads. Seems to me the shorter case would be more tractable for reduced loads than a long/thin one. There is some practical reason for inquiring about this. I have given some thought to getting a .300 WSM and loading it down to 300 Savage/ .308 / .30-06 velocities for deer and pactice but still have the horsepower there if and when I needed it.

(Just reached a milestone: 200 posts.)

Well, this would indeed further eliminate the potential platform advantage a shorter action in standard weight (not test) rifle would demonstrate. The point I was making was the typical rifles long action may exhibit more flex than a shorter action of the same design.
Using the same long action for these tests and further a test gun that is much stiffer than a typical rifle action would not show any potential platform advantage that a shorter action may have. Or maybe to be more precise would not show the disadvantage that the longer action in a typical weight action might display regarding more flex.
Again I am not trying to say there is any ballistic advantage to a shorter case, but there may be a platform advantage in any given action due to the shorter action (all else being equal) being inherently stiffer.

Accuracy/velocity/feeding aside, I appreciate the platform difference the WSM's offer. Like my Kimber and BLR. My 24" barreled WSM Kimber is only fractionally longer than my 22" M700 30-06.

I'll take tall and thin over short and fat any day. What were we talking about again?

"Aside from case shape having almost no effect, the most interesting thing to me was that the same powder was most accurate overall, whether the barrel was chambered for .300 H&H or .300 WSM."

And what powder was that? (You tease.)

Ella

The question calls for TWO answers �

� Given the same or closely comparable velocities, there should be little or no significant difference in exterior ballistics.

� The Law of the Inverse Square favors the short, fat cartridge for more consistent interior ballistics from shot to shot � especially from a very cold barrel. The difference is usually insignificant unless the primer-powder combination is prone to slight hangfires. (Some can be so short that you can't notice 'em. Then the effect on the exterior ballistics becomes a very significant and often mysterious matter.)

Unfortunately, one test proves nothing. Another test, especially with two other cartridges under drastically different conditions, may give drastically different, even diametically opposite, results.

Ella,

Ramshot Hunter. The other powders were H4831 and Reloder 19.