Lake City 173 Match BC?

[HumpHammrr]

I have a quanity of the old LC 173 grain .30 cal FMJ bullets. At one time there was an application that would give you a BC number based on projectile length and diameter.
Does anyone know the BC of this projectile or know where to find the calculator? I looked on JBM but theirs is velocity based.

 

[NukeMMC]

Re: Lake City 173 Match BC?

Some of the old timers would use 180gr SMK data as a comparable.

 

[HumpHammrr]

Re: Lake City 173 Match BC?

Thanks, I'll give that a try.

 

[Hummer]

Re: Lake City 173 Match BC?

173s will stabilize in as slow as 13.8 twist (got the rifle for it). That is the good news.

They can vary in weight several grains and still meet spec.
They were made on four different machines all making slightly different shaped ogives/meplats and mixed together to load each lot.
They can run from .308 to .3089 in diameter.

How well they shoot depends on how the bases look. First off look at bases and you will see variation from just a little lead showing to it is all over the base. Base integrity is critical in bullets.

Segregate your bullets in batches from least lead to the most lead. Shoot a group with each and I believe you will see the smallest lead exposed bases will shoot the best group.

The best news is once they go to sleep they will remain that way all the way into the ground shot from 31 deg elevation. They will not tumble when they drop below speed of sound.

Larry Moore made 11 US Palma Teams shooting 173s off one machine at LC shooting against Sierras.

 

[HumpHammrr]

Re: Lake City 173 Match BC?

I segregated them by weight and came up with several hundred of each weight. Probably 600 total. From a M40ish style Winchester M70 they stay in 1/3 moa.
I'm using a Ballistic Program on a Blackberry from Pejsa. It's a xcel spreadsheet with formulas. Hence why I was looking for the BC on these bullets. If the weather will clear up I'll take my Chronograph out and get their muzzle and 100yd velocities for a BC.

 

[asbestosglove]

Re: Lake City 173 Match BC?

I still have a 3000ct. box I got from CMP around '90. They also offered Blem 168SMK's in plain brown boxes for nearly nothing. Those were the days!

AG in NC

 

[Jerry m]

Re: Lake City 173 Match BC?

Try 0.468.

Good luck

Jerry