Hornady 168gr BTHP (30 Cal)

[patriot87]

Hey fellas, just looking for some advice and/or some experiences with the Hornady bullets.

I've been finding the overall lengths of these bullets drastically differs, therefore I got a comparator and started measuring from the Ogive. This has given me pretty consistent loads(most within .002 " but the odd one within .010") My question is I am using RCBS .308 small base dies and I've been noticing that after every box of 100 rounds my ogive is vastly different, so I keep having to adjust my die set after every box of 100. Is this normal with hornady rounds? Also I notice each box of factory rounds have different ogives and different COALs... just seems odd to me. I haven't had any pressure issues yet and I've loaded up to 43gr of IMR 4064 with the COAL varying between 2.805 and 2.820.

Any insight would be helpful, thanks guys!

 

[rodregier]

HPBTM projectile noses can vary some in dimensions, so chasing uniform OAL can be a challenge.
They make projectile nose uniforming tools for that if it bother you or if you feel
it is a parameter worth optimizing.

Typically seating dies are based on a datum point further down the projectile body,
which is also the case for barrel throat offset too.
A decent press + such a die will produce ammunition that has a consistent
gap between the chamber throat and the projectile datum point.
(aka "bullet jump").

There are gauges for measuring cartridge and projectiles at the datum point that will give you a much better
indication of the important spots than measuring OAL.

ht tp://www.sinclairintl.com/reloading-equipment/measuring-tools/bullet-comparators/sinclair-hex-style-bullet-comparators-prod83792.aspx

 

[patriot87]

Fair enough, thanks for the reply! In your opinion am I playing with fire by making sure every round (in this case) has the same or relatively the same ogive? My concern on this centered around the fact that if the Ogive is different with the die at the same seating does that mean the bullet will be further in/out the case? Or will measuring from the ogive make sure the round is going to be about the same pressure wise each round.

Thanks again

 

[bsand]

Since I've been using 175 sierra matchkings my OAL is within 0.03". I actually haven't had to adjust my LEE seating die for the last 500+ rounds, I just seat one round measure and measure every so often. Always within 0.03" usually 2.841" or 2.8405". At first I tried to get them all exactly the same, but wasn't happening so I just left it to be good enough and my accuracy hasn't changed.

 

[rodregier]

Ogive datum point is more important for pressure and accuracy than any OAL measurement.

Ideally you want to set up the cartridges so that the projectile jump to the chamber throat is within some reasonable range.
If you are radically changing the effective seating depth you may have to redevelop the load for pressure considerations.
My goal is around 0.015, YMMV.

The projectile jump to the chamber throat can be a tricky measurement to make.
Each rifle can be different too.

My experience is that once your have the datum point setup it produces a similar throat jump for different lots
of the same projectile. It's another matter if you also start using a different projectile.