cart SHOPPING CART You have 0 items

Discussion Forums

Search forums
Forum Index > Rifles general discussion > Case Overall Length vs Case to Ogive Length which is better?

Case Overall Length vs Case to Ogive Length which is better?

18 Jul 2014
@ 05:55 pm (GMT)


I had just reloaded 100 30-06 cases for my Remington 1903A3 with 155 grain Sierra Matchking projectiles. My COAL is 3.300 which gives me room for smooth magazine feeding. After measuring all 100 rounds I was shocked (as it actually worked) that my COAL for 95% were exactly 3.300 & only 5% were 3.305 which I re-adjusted to 3.300. My Forster micrometer seating die worked a treat.

Now my dilemma. I measured all 100 cases again with my Hornady bullet comparator to ogive length & they were all over the shop, some longer whilst others shorter, but all had the same COAL. I had measured all original test rounds during load development & the most accurate measured COAL of 3.300 & case to ogive of 2.598.

So is it better to I ignore COAL & go with case to ogive? But if I go with case to ogive my seating depths are changing which I assume would lead to pressure changes per round.

Any advice would be appreciated


18 Jul 2014
@ 06:51 pm (GMT)


Re: Case Overall Length vs Case to Ogive Length which is better?
I always thought the ogive measurement was better. I have no reason why. maybe ogives are more consistant than tips. I guess your going to get differing measurments no matter what you do unless you measure projectiles and sort then.
I have sometimes weighed projectiles when I have time to kill, mostly to set aside the few extreme deviations.
I guess just pick a method and stick to it.
18 Jul 2014
@ 06:58 pm (GMT)

Bob Mavin

Re: Case Overall Length vs Case to Ogive Length which is better?
G'day Mark
You could use your Hornady Ogive piece in your callipers and group your projectiles into different lengths, from ogive to base, a couple of thou shouldn't matter.
19 Jul 2014
@ 04:42 pm (GMT)

Nathan Foster

Re: Case Overall Length vs Case to Ogive Length which is better?
Hi Mark, when you set about obtaining a COAL, whether taking measurements off the ogive or tip- record the actual length of this first test projectile (whether you record length to ogive or length to tip).

Following this, set your jump based on this test projectile. Set up your seating die, then go about seating bullets.

The COAL of your batch of ammo will vary- do not adjust the seating die.

If you (for example), load some ammo with the SST and have to change the seating die settings, you can go back to your 155gr bullet settings by selecting a projectile with the same specs as you initially wrote down.

Both ogive and length to tip can vary from bullet to bullet so record keeping is the key. Also, if a brand of bullet shows great variation in length to ogive, it can pay to opt for increased jump. As an example, someone searching for extreme accuracy with the Berger VLD may want to start at 10 thou jump- however the differences in ogive may cause slight differences in pressure and have a negative effective on accuracy. In some instances, Berger bullets may show up to 20 thou variation. In these cases, it is better to opt for 40 thou (1mm) jump to ease pressure differentials, resulting in more uniform accuracy and a lower extreme velocity spread.

This is part of the subject matter for the next book in our series.


We are a small, family run business, based out of Taranaki, New Zealand, who specialize in cartridge research and testing, and rifle accurizing.