Some 30 Cal BCs Tested

[Jon A]

Certainly not all-inclusive but I figured some would find the info useful. I measured in about the most accurate way possible for anybody without a million dollar underground range and I'm confident in the results. Of course I wasn't shooting 10 shot strings which would have upped the confidence level (some bullets were more consistent than others) but that'll have to wait until somebody else is buying me barrels. [img]/ubbthreads/images/graemlins/wink.gif[/img] Anyway, for what it's worth:



Calibrating the Oehlers:



The 206 yd target/205 yd chronograph, with spotter target to the lower left:



The view:

[1doug]

excelent work. Looks like the 210 MK will be one of the new kings of the hill in the 30 cals.

Why 200 yards difference instead of 300 or more? I am gonna be doing the same thing buy at farther ranges @ 500


d-a

[Hired Gun]

[ QUOTE ]
Why 200 yards difference instead of 300 or more? I am gonna be doing the same thing buy at farther ranges @ 500


[/ QUOTE ]
No problem. Can we use your chronograph at the 500 yard target?

[edge]

Great info, but it makes me wonder why the flip flop of the Sierra B.C.'s

Have you shot the 240 SMK at long range? If so does it hold the same vertical zero as the 210 SMK?

It almost seems as though there may be a stability issue?

Sierra lists the 210 SMK with a B.C. of 0.620
and the 240 SMK with a B.C. of 0.711 ( at your velocities )

Looking at the pictures that you supplied, the ogive of the 210 SMK sure looks like a larger radius to me and therefore should have a better form factor, or am I missing something here?

thanks for the info.

edge.

[jmden]

Great work. Thanks for posting. Could you explain how the two types of BC's are arrived at?

Thanks.

[remingtonman_25_06]

Ha, just goes to show how over rated barnes BC is. Thats all I wanted to say.

[davewilson]

the thing that struck me when the 210 SMK's came out was that they have a secant type ogive. this seems to be a first for sierra. other bullet makers use this style of ogive as it seems to produce a higher BC than a tangent.

thank you very much for posting this. this is the absolute best kind of info long rangers can have, thanks again.