Home Forums Hunting & Shooting Ask The Gunwriters How is Optimum Game Weight Calculation done?

It seems to favor "momentum" over "energy" but I cannot figure it out and it does not seem to be valid.

A 22 caliber 62 grain bullet going 3000 FPS generates an optimum game weight of 141 pounds at the muzzle, while a 30 cal 130 grain going 2000 FPS generates an OGW of 203 pounds at the muzzle would seem to be backwards to me.

It is plucked out of the air, probably on moonlit nights.

Don't over think the math. Just buy a .270WCF.

I disagree with the esteemed Mule Deer...

I do not think there is anything near as scientific as that involved in "optimum game weight"!

John

I concede!

The problem with trying to reduce "killing power" to an engineering problem is that animals aren't steel targets, much less bridges.

And even when somebody comes up with a formula that might have some real exoerience behind it, such as John Taylor's "Knock-Out" formula, it gets used incorrectly. Taylor initially published it in his first book, specifically stating that it only applied to solid bullets on large game from buffalo to elephant. Trouble was, he didn't mention that in his second book, and now every other SCI member quotes "Taylor numbers" when explaining why some cartridge isn't truly adequate for anything from dik-dik to Siberian moose.

In my younger years I even formulated a killing-power formula, but had the good sense not to publish it. Since then I've come up with another, which I have published: B-2L=D

B is bullet, 2L is two lungs, and D is dead.

Well I for one never bought into the Taylor line. A whole lot of things just don't add up with him, but a lot of hunters think that he is has the final say. Well its like this, you want to hunt say deer, make it White Tails because I have shot more of those than any other up to this date. We are talking about a very soft thin skinned and small boned animal. You don't need much cartridge to collect one, one of the most successful deer cartridges ever made is also one of the very oldest smokeless power rounds, The 30-30 Winchester.Plenty for White Tails and other game as well, its it the best under all conditions, nope, then again you could say that just about any cartridge or rifle for that matter. But a decent bullet into a deers lungs Heart or break its neck and get out your skinning knife. Even a 22 RF will get the job done if pointed right.

A lot of African PH's don't buy Taylor's formula either!

Wasn't Taylors formula based on some "Knock Out" value to predict whether and for how long a head shot elephant would remain unconscious from a shot(with solids) that missed the brain?

Yep.

JB:Thanks

The Matunas Optimum Game Weight (OGW) formula is explained on the BigGameInfo website. This seems to be more realistic than Taylor's formula.

Aren't there enough cartridges filling all the gaps between .17 and .50 caliber and enough available experience with those cartridges to have a reasonable expectation for how any particular style of bullet of a given diameter and weight at a particular impact velocity is going to behave?

If one has a .308" 165 grain cup-and-core bullet of a particular brand impacting at 2400 fps, one can get a good idea of what to expect with a little research without needing a formula - and that's coming from one (me) who likes to put numbers on everything (and whose formal training has taught him to do so with some competency). If you can't find the info in your research, you can ask here.

Even the most unusual wildcats are going to behave closely enough to some existing cartridge that one can get some info on how that cartridge would behave on any type of game one was interested in hunting.

It seems to be more mathematical and deliberate than the moonlight plucking method would indicate, so I was curious about the formula.

Its a curiosity found in places along the trail on the world wide web and looked remotely similar to the results proposed by Earl Harmon Quackenbush in the early 50's on page 57 of his book "Quackenbush in the Bush"

Just sayin.

Big shrug.

Any killing-power formula, no matter how nifty it sounds mathematically, is plucked out of moonlit air, especially when it suggests a "maximum range" at which a certain load will work.

And even when based on any formula, the formula is derived at least partially from field experience in the first place. Though sometimes not! There's another killing-power formula in the 6th Speer loading manual, formulated by an engineer who has very little field experience. Maybe this is what's meant by "reverse engineering."

Quackenbush in the Bush and plucking... Isn't Ingwe the expert here????

Yep...I got the formula....28.5 grains H335 behind a 50 Gr TTSX in a .223AI= Dead Bambi......

jimmyp,

One apparent failing (among a number of failings) of the optimal game weight type formulas is that they fail to factor in what the minimum impact velocity for a particular bullet is. Some bullets will expand at 1800 fps or less while others of the same diameter and weight don't appear to reliably expand below 2000 fps. Another failing is the failure to account for the differences in bullet construction, which affects penetration, expansion, etc. There is a lot more to bullet performance than bullet weight and muzzle velocity (and, in some formulas, diameter).

Yea, but could you hit Bambi at this long range?

I've got a Ballistic Plex Reticle.....of course I could...if I used the right dot....

As a holder of an earned PhD in mathematics, I assure you it's entirely possible to come up with something "mathematical and deliberate" that doesn't mean a whole lot.