April American Rifleman Article about the 6.5 Creedmoor

[1mlt]

I leaned something new today. Short article, 2 pages. The 6.5x55 Swede gets some ink also. I love my Swede. I guess that's why I never researched the 6.5C. The 6.5mm Creedmoor (isn't really 6.5mm) was BC compared to the 6.5x55 Swede and the 25-06 Rem . I thought the 6.5C was developed from a necked down .308 case. I was wrong. However, in my defense, I never researched the round since I have the Swede. I have now. Pretty impressive BC's. But, I'll keep the Swede.

Creedmoor bullet diameter is 6.720mm/.2644".
Swedish Mauser bullet diameter is 6.710mm/.2640".
.25-06 Remington bullet diameter is 6.527mm/.257".
.308 Winchester bullet diameter is 7.80mm/.308".
.30-06 Springfield bullet diameter is 7.80mm/.308".

(From Wiki): It was developed from the .30 TC (Thompson Centerfire) case. The .30 TC (0.308 in (7.8 mm) x 1.920 in (48.8 mm) is a non-magnum that is somewhat shorter and wider looking compared to the .308 and .30-06.^[1] However, while in a gun, all three weigh roughly the same but the .30 TC produces less recoil. The case length of the .30 TC is 1.92 inches. Although it is somewhat shorter than the .308, the .30 TC still manages to cast a 150-grain SST bullet downrange that is nearly 200 fps faster. The .30 TC can even outshoot the 150-grain SST faster than the .30-06 case, which is also longer in size compared to the .30 TC (2.494 inches). The .30 TC has a performance delivery equivalent to the .30-06. The cartridge is approximately an inch shorter if one uses Hornadys Superformance ammo.^[5] When loaded with the 165-grain SST bullets, the .30 TC has a fifty fps advantage over the .30-06, which has a velocity of 2,850 fps. The .30 TC delivers energy and speed that equals to, or tops the .30-06 as a smaller cartridge.^[6] Trends in ammunition has changed over time to be shorter and wider than previous cartridges. It has been understood that gunpowder burns more efficiently in shorter casings that have a wide diameter.^[6]

 The Creedmoor measurements in the article are:
0.264" (6.7056mm) neck ID. 
0.295" (7.4930mm  neck OD.
0.473" (12.014mm) base diameter. All measurements began at bottom of base.
1.490" (37.846mm) to the shoulder.
1.635" (41.529mm) to base of neck.
1.920" (48.768mm) overall case length. This is where I really started scratching my head. The 'inch' seemed way to short to me. Should be 2.01" or so. I go to Wiki and discover my "birthing"error.
2.825" (71.755mm) overall length.

6.5 Creedmoor per Wiki:
0.2644" (6.72mm)   bullet diameter.
0.2950" (7.49mm)   neck diameter.
0.4620" (11.73mm) shoulder diameter.
0.4703" (11.95mm) base diameter.
0.4730" (12.01mm) rim diameter.
0.0540" (1.374mm) rim thickness.
1.9200" (48.80mm) case length.
2.8250" (71.80mm) overall length.

Here's some more numbers for you. I couldn't resist doing the conversions. I wanted to see what mm looked like in inches. At this point, I'm laughing at myself for my error. Maybe ALL ammo should be in mm. Makes it way easier for me anyway.
6.5mm = 0.2559".
8mm    = 0.3149".
9mm    = 0.3543".
25mm  = 0.9842".
51mm  = 2.0078".
55mm  = 2.1653".
57mm  = 2.2440".

Marcus

[carls sks]

thanks for sharing.