I have to agree that the Mausers hit a nice balance between bore diameter and case size. I've got a 6.5x55 that I put together, and I'm working on a 7x57.

Dutch, the idea that the CARTRIDGE is what is overbore, not the RIFLE is a very interesting one. That may resolve some of the issues. In fact, that "muddle" seems to be in the middle of the issue.

As I've thought about it, I'm not so sure Ackley is so far afield from the SAAMI definition. I think he may have just put it a little more compactly...."contains more powder than can normally be burned" is about the same thing as saying "lots of energy goes out the muzzle in the gas", which is low efficiency.

Howell and Powley are certainly a respectable pair. Their definition is at odds with SAAMI, because SAAMI specifies that it's the firearm that's overbore, while the informal version of Howell/Powley I grabbed off another board refers to a loaded case and bullet, which is what you've been saying.

Hodgdon doesn't seem to know whether they are talking about a case, or a firearm. They talk about a "cartridge case that has too much case volume for its bore volume." Well, last I checked, dang few cases have bore volumes. Guns have those. And I agree that their snide remark about "unscientific" is out of bounds.

So, I'm as confused as ever, but on a higher plane, and about more important things...

Very interesting discussion, gentlemen. Myself, I grade cartridges as to the degree of "overboreness" (how do you like that? now there's a scientific term!) simply by the ratio of case capacity to area of the bore. The bullets, powders, and barrel length (bore volume) are all variables, which can be changed. The case capacity ratio to area of the bore is set in stone for a given cartridge. Actually, the ratio of case capacity to volume of the bore is also constant, if you always use the same barrel length in comparisons. These ratios are useful in "grading" expected barrel life. However barrel life can vary greatly depending on many factors, such as:
1.) How "hot" your loads are.
2.) How hot you allow your barrel to get.
3.) How well you clean your barrel.
4.) The type of powder you use. Ball powders
are rumored to give longer barrel life,
because they burn at a lower flame temp.

I don't know if there is such an animal as a "perfect bore" cartridge. Whatever it is, I don't lose any sleep over it. It probably is a 22LR! But it makes for interesting discussion.

As an aside, once again I notice that whenever someone wants to give an example of an "overbore" cartridge, the first example to come to mind is a .264 WM. Why is that? There are any number of cartridges which are more overbore than the venerable old .264, some of which are of even longer lineage than the .264. Anyone heard of the .257 Weatherby? This case is more overbore than a .264, yet rarely mentioned in these discussions. There are, of course, quite a number of newer cartridges which leave both of those in the dust, so to speak. The 7mmRUM comes to mind. (The 7mm STW is a twin the the .264 as far as ratio of bore capacity to area of the bore.) Just an observation. Have a great day!

I, too, rate cases by computing the ratio of case volume to bore area. It's analogous to bullet SD. The results can be converted to inches of bore. The .257 Wea is among the "longest" commercial cases in this respect. A magnum pistol cartridge is about 1 inch. A .308 is about 3 inches, and a .257 Wea is 6.5 inches.

The equations from the Powley Computers can be rearranged to make this number and bullet SD the two "variables" which determine the correct powder quickness to use.

asdf

Yes, another use I make of the ratio of case capacity to area of the bore, is if you have two cartridges which have a similar ratio, (but different bore size) and if you have a load for one with a certain powder, you can suspect the same powder may work similarly in the other, if you compare them using bullets with the same sectional density (and bullet construction).

mudstud:

I've found this to often be true when comparing "proportional" cartridges. You can just scale the powder charge by the ratio of the bore areas. When I say this is "true," I mean you can find this to be so in pressure tested load book data. However, I can also find examples where it didn't scale, but then again, any two loads book will often disagree on what the correct charge is.

I should note, the comparison has to be made among cartridges VERY close in Chamber/Bore. Differences of 0.2" in this ratio are very signficant.

Regardless, with ALL of the internal ballistics software I've tested -- QuickLOAD, Powely, etc. -- if SD and Chamber/Bore are the same, then so is the predicted performance.

Chamber/Bore is a useful ratio.

Most if not all the catridges on your list are great killers so I guess my question is, "What difference does it make?" Over bore or under bore dead is dead. "Perfect" bore doesn't seem to work noticably any better than under or over.

quote:

Originally posted by ALF:

The "ideal cartridge" in our current ballistics model and line up has the case capacity of the 338 lapua and a bore diameter of around .366 inches. ie roughly a 8.5 to 9.3mm caliber on a 338 Lapua case.

Alf,
The .338 Lapua Magnum is nominally 8.6x70mm. It must be in this "perfect" range of 8.5 to 9.3 mm.

How about allowing a silly 0.2 mm extra? A 9.5 Lapua or .375/.338 Lapua Magnum.

The .375 Lapua has an identical case capacity as the .375/404 Saeed. I think that has proven to be quite efficient.

There sure are a lot more bullets available for the the 9.5.

I vote that the bore range of perfection be extended to include 8.5 to 9.5 mm on the .338 Lapua Magnum case.

After all, that is only one little silly millimeter for the entire span of possibilities on the case at hand.

Also, aside from the brass perfection of the Lapua case, does this "perfection" imply that it provides

Optimization of ballistics/bore capacity match

AND portability (of ammo and gun)

AND shootability by mere mortals in combat or tactical military/police work?

To extend this to sport hunting we definitely must include the .375 in this case, pun intended.

Perfection: 8.5-9.5mm/.338 Lapua Magnum.

For my 2 cents worth I believe effeincy of what they can do velocity wise is a valid argument as there are alot of cartridges that were ahead of there time for the powder available.good examples are the .30 newton and the.25-06' these were well ahead of their time. I shoot belted magnums because I own them and in alot of cases they do not achive any worth while accomplishment as far as velocity gain. I can name the most all of the Newton cartridges as perfect examples.The 0ld standbys are some of the best and they will probably always be here .270 .3006 .22-250 .25-06 .30-30 that comes to mind they are all useful and modern day stats are much more impressive than when they were intoduced. I am not a fan of the short mags but I do feelthat they are more accurate in a barrel vise. If you have a good old fashioned chambering you dont need any thing more. just my 2 cents

I also want to say that progress is progress and that the shooting industy was stagnant for a few years. We should feel fortunate that we have the choices that we have to form our own opinions and cartridges are getting better.
Who knows maybe one day they might (our government) may sell to us a better battery (uranium) and may supply more efficiant propellants!

Can't agree more with cal30. Although I think many of the new offerings of factory cartridges are redundant or only marginally better than the old stand-bys, who can argue with an excess of cartridges?!

For example, you could argue the merits of the .300WSM versus the .300 WM all day, but in the end, there's very little difference in their effectiveness on game, or even on target. Chalk it up to good fortune that we (and the ammo companies) have the freedom to make a .22-50BMG if we feel like it!

You gave this thread the right name. roger

It depends on what their purpose is. For shooting sparrows @ 30 yds the 22 lr is well adjusted. For large deer in thick woods the capacity of the 358 winchester is more than adequate, but for punching holes in paper @ 300 yds they might both be a little underbore.

A couple rounds that I personally feel are exceptionally well adjusted are the;

6.5X55

280 remmy

300 SAUM

338 WM

and the 376 Steyr, to name a few.

35 whelen AI