Tikka 6.5 Creed 20" Load data

[Tahoe1305]

Can you help my understanding, does loading long (close to lands) result in more velocity (higher powder capacity?), better accuracy, or something else? I ask because its my understanding that Eldx and Eldm shoot very accurately at factory COAL. I haven't yet measured how much jump this COAL is in my tx3 6.5CM.

On paper, a 20" barrel looks to be better suited for 130 ELDM, 130 MK, or other high BC "lighter" bullets at 2800 fps appears optimal for a 20" barrel tikka inside of 600 yds. I see higher impact velocity, similar energy, and slightly less drop than a 143 ELDX at 2650fps, using Hornady's ballistics calculator. These are ballpark handload speeds for 20" barrel based off what folks have posted online.

I get 2578fps with factory 143Eldx out of my new 20" TX3, which is too slow for my liking. Working up some 143 gr and 130 gr handloads to determine my final bullet choice for hunting.

Effects of Cartridge Over All Length (COAL) and Cartridge Base To Ogive (CBTO) - Part 1

Many shooters are not aware of the dramatic effects that bullet seating depth can have on the pressure and velocity generated by a rifle cartridge. COAL is also a variable that can be used to fine tune accuracy. It’s also an important consideration for rifles that need to feed rounds through a...

bergerbullets.com

Check this out. Written by Bryan Litz and explains it best I think.

Essentially you are “wildcatting” the cartridge a bit seating the bullet out far. This allows for more capacity in the case and typically more velocity. It’s also the reason tikkas (at least in 6.5C) are typically slow loaded to saami limits. There is too much unused volume in the throat. At firing, that volume fills and is inefficient use of the explosion thus comes out slower than you’d expect.

Hope this helps.

 

[Frozenlead]

24” t3x varmint 6.5cm
2683fps
140 Berger EH seated near mag length
43gr N555
White river LRP
Hornady 1x brass
The factory 147eldms run around 2600fps