6.5CM Freebore Diameter Recommendation

[JRock95]

About to get my first 6.5cm built. I'm new to the idea of choosing a freebore diameter. It looks like I have the options of 0.199 or 0.169. From what I'm reading, I'm leaning towards 0.169. I'd like to have the option of trying a few different bullets and grain weights between Berger and ELD-M. Any thoughts on which diameter to go with?

 

[Hondo64d]

That would be freebore length, wouldn’t it?

John

 

[vonb]

.169 is tight. I did one and the 140s are seated short. Just know you’re seating deeper unless you are using Bergers.

 

[Andouille]

What ia the max COAL your magazine will accomodate? One thing to consider is that Seating long gives about 20-25 fps for every 0.050" out from factory load COAL, with increased powder charge and no pressure increase, per a few calcs I ran in GRT for my tikka 6.5cm.

Not sure what the "long" throat is in a Tikka, but it seems great for reloading, but the magazine length is limiting with 147 eldm or anything longer.

 

[wind gypsy]

That would be freebore length, wouldn’t it?

Definitely length. A 0.264" bullet wouldn't be very "free" in a 0.169" or 0.199" diameter freebore.

0.169 probably plays nice with 140 hybrids and the like and probably a little tight with 147 ELDms.

If you plan to primarily shoot 130s and lighter or shorter bearing surface bullets like 140 hybrids the 0.169 might be nice. Otherwise its not the end of the world to jump another 30 thou with longer freebore either.