Why the 6.5 caliber?

[crystalgayleguy]

someone had an ideal and ran with it

 

[nicholasjohn]

I think it comes down to the old guns that were .264 in diameter. 6.5mm happened to get lucky in that they have almost always been blessed 1:8 twist barrels. So, the bullet manufacturers were able to push the limits without limiting their users. Even the new 156 can be pushed in a 1:8 with reasonable success.

Everything else settled on reasonably slow twists, esp the .257 and .277.

I think you've got the answer. The 6.5's have always used fast-twist barrels ( to stabilize the 156-160 grain round-nosed bullets ) and what's really going on here isn't a 6.5 thing - it's the long & heavy bullets that improve downrange performance that everybody is after - not that particular bullet diameter. If the 270 or 7mm had was set up in a fast-twist barrel, it would do the same thing. It's just that the 6.5's have always been done that way, so they got a head start on the other bullet diameters.

Now everybody is having custom builds to do the same thing with the other bullet diameters, and the bullet manufacturers are slowly rising to the occasion with long-for-caliber, high-BC bullets. If the 30/06 had originally been set up in 1-in-8 twist barrels, and really heavy spitzers, then the 30-calibers would be the one enjoying this huge popularity. As it is, they are just now catching the wave.

Before too long, I think we'll be seeing long & heavy bullets for ALL the commonly used bullet diameters, and fast-twist barrels to shoot them through on factory rifles. It's kind of ironic that the bullet diameter that was once the least popular caliber in this country has been the one that led the parade in this movement.

 

[Bart B]

The 6.5x55 Swede was "the" cartridge for 300 meter free rifles in international and Olympic until the late 1950's when Sierra Bullets made their 30 caliber 168 HPMK's for the USA Olympic and Army International rifle teams. Norma 139 grain FMJBT nickel plated match bullets were the best available before Sierra's 168 came about. Henry Cross, the USA team captain, was instrumental in making this happen. Those 168's were shot 2200 fps in reduced loads soon breaking world records.

It was around 1990 that the 6.5x284 started to replace the 30 caliber belted magnums in 1000 yard matches. It bucked the wind almost as good as the 30 mags but its much milder recoil enabled better scores because the rifle moved less while bullets were going through the barrel.