Caliber Configuration Podcast with Yours Truly at Gun Guy Radio

@6.5x55Swedish Well, he was rather more considering how that black powder boolit era thinking dragged itself into the first half of the 20th century, when smokeless propellants and spitzer projectiles had made it unnecessary. There had been a continuous push toward smaller calibers (30 cal was considered a small caliber in the late 19th century), but the poor terminal performance of round nosed, jacketed bullets had been a serious set-back for the small caliber philosophy. And, as Nathaniel mentioned, the early AP and tracer rounds were tricky for anything much smaller than 7mm.

@6.5x55Swedish That wasn't really what I intended to say, but it was an extremely abbreviated discussion. I covered like 100 years of history in a minute or two. Bound to be a little garbled.

@mechamaster What are you smoking and how can I get some? We should keep our 308 or replace it with something like either 25-06 or 338 Lapua. The reason why I say this is because it would further increase our range with a negligible increase in weight. Now, 5.56 ought to be replaced with some kind of 6.5mm round -- light, low recoil, hit hard. We've hit the limit as far as 5.56 goes and we're trying to solve the lack of lethality issues in a fragmentation-dependant round by making it even better at penetration. Try to puzzle that out for yourself. Study after study has found a 6.Xmm round to be the ideal infantry caliber, although Nat claims to have access one one that says it's close to 5mm, although he's so far declined to share it with anyone and all the powers of the internet and doing searches in 3 languages across 5 search engines and asking across multiple forums have turned up nothing. IMO, with rounds available right now, I'd replace 7.62x51 with 270Winchester for a full 33% increase in energy for negligible increase in recoil and an improvement in ballistic coefficient. I'd replace 5.56x45 with 6mm PPC, a very accurate cartridge with a very high increase in energy and ballistic coefficient from 5.56 at negligible incresae in weight and recoil.

@Cmex .25-06? How many spare barrels to you want to force the Weapons Squad to carry, man?

I feel like Sisyphus whenever anyone brings up the "all studies ever done have all concluded the 6.5mm is best". It's my fate to just keep pushing that boulder uphill, says the Oracle at Delphi.

Well, here's a head-scratcher for you: For almost half a century, most studies conducted in countries across the world, with a handful of exceptions, determined that .30 cal was the best infantry caliber there was. France, Japan, the USA, the Italians, and numerous others all conducted studies and came up with .30 cal as the "ideal". So why didn't they all conclude that 6.5mm was the best? Were they all stupid?

No, they had different requirements. There are requirements that will lead any research team to conclude that 6.5-7mm is the best caliber, but not every study started with those requirements (in fact, most didn't).

It continues to baffle me that this myth gets repeated in serious ammunition discussion circles so often, as many times I've seen it rolled out again by people who are aware that in the 1950s, the US Army conducted a caliber configuration study and settled on the .22 caliber! It was that study led directly to the 5.56mm. Here is my proof that this study occurred, below are cartridges in my collection, some of which were created for that study:

http://i.imgur.com/XgbKIvT.jpg

The middle three are the .22, .25, and .27 Light Rifle, each basically 7.62 NATO necked down to its respective caliber.

Here's just a hypothetical example to make it clearer: Let's say I am going to order a study on what the best infantry caliber is. I am going to tell those conducting the study that the caliber must be able to penetrate 15mm of armor at 1,000 meters, because there is a requirement for infantry to be able to engage technicals at standoff distances. They come back to me and tell me they've determined the ideal infantry cartridge is the .416 Barrett.

Should I then go to all the forums on the Internet and parade around my study as the ultimate and final answer on what the ideal infantry round is? No, of course not! Not even if I'd conducted a hundred such studies. The requirements of the study don't match the reality, obviously.

So, "every" study ever conducted says 6.whatever millimeter is the best. ...Including studies conducted in the 1890s, 1920s, and 1950s, I presume. How relevant is a study from the Fifties? From the Twenties? From the Eighteen Nineties? Probably not very relevant! Much has changed in both infantry combat and ammunition design since.

That doesn't mean the 6.Xmm caliber isn't the right choice, either, but just throwing out that line - which isn't even correct at all, as there are as many if not more studies that point to other calibers as there are ones that point to 6-7mm - as the final word in the discussion is ludicrous.

@Cmex Cause an improved high pressure 6.5mm round like the 6.5 Unified (from Soviet Union) would be lighter than 308 whilst providing better range and trajectory.

@iksnilol The cartridge you're thinking of is the 6mm Unified, not 6.5mm.