Estimating BC ....help!

[Brown Dog]

Got 50rds of 308 Geco 170gr target ammo for which I'm having trouble finding / estimating a 'starting point' BC to put me 'in the Parish' before I launch any downrange tomorrow.

They have good ogives but flat tips….....I'm confused!!
(yes, despite appearances,they are marketed as target bullets).

What would you estimate (I believe they are flat base)??:

Geco in the middle, 165gameking on left (0.404), 165NBT on right (0.475)……the ogives appear similar….just the tips seem different:

The ogive is looks too good to class them with the Sierra Prohunter 170 FN (BC: 0.204).

Some more views of the Geco 170gr tip:

Anyone got anything more edumacated than (0404 + 0.475 + 0.204)/3 = 0.361 ?


Thanks!

 

[Fotis]

.350?

 

[Fotis]

kINDA LIKE THESE:

Awesone performance. Too bad Low BC.
/ubbthreads/images/graemlins/crazy.gif

http://www.northforkbullets.com/308-165.htm

 

[Buffalobob]

look at the Speer 30 cal Mag Tips

170 gr has a BC of 0.304
180 gr has a BC 0f 0.352

 

[Brown Dog]

Thanks.

That's brought the average down to about 0.34.

-I'll give it a go at that!

 

[wapiti13]

BD, Unfortunately, flat nosed, flat based bullets have a much lower BC. Hopefully, they shoot great to offset their range limitations. Good luck.