COAL with lead tipped projectiles

[Geoman]

Just finished loading 50 rounds of .308 WIN with Hornady 180 SP projectiles.

The COAL called for in the Hornady manual is 2.74, but I found a wide variance in the final COAL using the same competition die setting; I set the die until I got the required COAL by increments, then subsequent cartridges would vary by as much as +/-0.005-0.007. It looked like the lead insert was being mashed by the seater.

The projectiles had a cannelure, so I used that as the correct insertion level.

So, my questions is: how to accurately measure COAL with a malleable tip in the projectile.

BTW, this is the first instance of this issue I've had. HP and plastic tipped projectiles did not exhibit this.

 

[Dawico]

You need a comparitor kit for your calipers to read them more accurately. It measures from the ogive instead of the tip.

You start with one round you are calling good and zero your calipers on it and compare your subsequent rounds.

Hornady makes a good kit with different sizes and is available at Academy.

Personally though, I don't worry about it too much if it is that close.

 

[Dawico]

Another way you can check is to slide a spent 22 (or similar shell) over the bullet and measure that. Then zero your calipers and check your other rounds.

Not as fancy but will get the job done.

 

[OLDVET]

I have had this problem with all of my rifle reloads. The COAL would vary by a couple of thousands on the majority of the rounds. I use a Rock Chucker press and either RCBS, Hornady, or Lee Precision dies.
I set the bullet seating die for each caliber just a tad long and then adjust as necessary to get the correct length.

I called RCBS a few years ago to ask why this was happening. Their guy said bullets are seated off of their ogive and not the bullet tip. He told me to not worry about the COAL length if it is just a few thousands of an inch difference. He said the ogive depth was more important than the COAL. Assuming the round fits your rifle. Seating a bullet deeper to achieve a certain overall length, decreases the cartridge's internal volume. This can cause higher pressures. I find a happy medium and load away.

 

[Mikewood]

COAL is usually only critical if you have a box magazine you are feeding from and are worried about the cartridges bumping into the front of the magazine and jamming or getting stuck during feeding. What you want to do is measure the lands in the chamber and seat your bullets just off the lands. Size a case. Hand Seat a bullet extra long and gently (not crimp) tension the neck of the case with a pair of pliers Gently insert it into the chamber and close the bolt. Then gently remove it. If you did this right you should see some dimples on the bullet where it touched the lands. Back that up with the bullet seater by a couple thousands and that is your max OAL. This works fine unless you are shooting a weatherby case. They have a ton of of free bore. So setup and size a dummy case and see if it will feed. If it's too long just shorten it till it will feed. Start at the minimum powder charge and work up slowly.



Sent from my iPhone using Tapatalk Pro

 

[popper]

I load so it fits the mag and doesn't jam the lands for AR. You can jam the lands a little on a bolt gun. No idea what my COALs are, just what works. I check or adjust the seating die on a dummy round. Published COAL is like MSRP.

 

[Geoman]

Bought a comparator, OAL gauge, and modified case. Followed the instructions and have now made a table of all the projectiles I'll be using with their correct OGIVE, both maximum at the lands, and recommended offset from them for the rifle I'll be using. I've just finished loading my first set and will report back results.

Thanks for the comments.

 

[Downhill]

Comparators are the only way to go. Gives the ability to locates lands when needed. Great for setting OAL. Bullet do have variations in length and weights.

 

[noylj]

As "Meatballs" should have taught,
"It just doesn't matter."
First, measure your bullets and see how they vary.
Second, measure factory rounds and see how they vary (and they load near Max/Max).
Maybe, if you were in the World's Series of Long Range Rifle Competition, where a 0.010" larger groups might lose the contest, it would matter.
Does it fit the magazine?
Does it chamber?
Can you SEE any difference?
If answers are yes, yes, no, you are good to go.
You can get as OCD as you wish, as long as you're safe, but time behind the trigger will do more for you than time behind a comparator.