***Careful seating bullets according to COAL***

Chinny33 · December 14, 2010, 03:09 PM

Greetings,

I was seating Sierra 85gr BTHP, for my AR-10 in 243win.

According to Sierra's manual, it is supposed to be seated for a COAL of 2.650". I loaded 50 rounds with that COAL. It sat really nicely.

As usual I double check everything and didn't realize that I completely ignored that I should check the throat dimensions in my rifle. So I used Hornady head space gauge and found out that my actual COAL should be 2.633"

So, out of pure curiousity I chambered a round. Well, STUCKO!!!!

Since I was careful not to let the bolt SLAM as it should, I was able to easily pull the round out of the chamber, noticing that the bullet was seated WAY too far forward. The rifling left small marks on the bullet, giving away that it is seated too far forward into the lands.

I ended up seating the bullets to a COAL of 2.621" and BAM I have some super awesome rounds that will chamber and shoot accurately since they're seated close to the lands of the rifling.

Be careful everyone. CHECK throat dimensions and not just blindly relying on manuals. You might end up really jamming a cartridge into a chamber and be in a whole world of mess where you have to shove a rod down a barrel on a LIVE round.

Note, since we are hand loaders/ reloaders we have the liberty to load according to OUR preferences and OUR tolerances, not according to general factory standards. Most benchrest or competitive shooters will purposely load their cartridges so that the bullet will seat almost touching the lands of the barrel, giving better accuracy and consistency. Heck, why not?

mehavey · December 14, 2010, 03:15 PM

Suggest changing term 'head spacing' to that of 'throat dimensions' and you are right on.

wncchester · December 14, 2010, 03:16 PM

"According to Sierra's manual, it is supposed to be seated for a COAL of 2.650".

Part of the "problem" is that so many people (incorrectly) think a book OAL is a "supposed to be seated" thing. It is not. It's only what the book makers used in their weapon to develop the data. But, their's isn't mine so I have to find what works for MY rig!

And chamber headspace is measured from the bolt face to the shoulder, not the end of the leade/throat. Cartridges don't have headspace but they need to be sized to match the headspace.

IllinoisCoyoteHunter · December 14, 2010, 03:16 PM

Good thing you checked. Some guys swear by jamming that bullet into the lands. I seat my Berger vlds .010" off the lands in my Savage Model 12 in .243 WIN... which puts the COL at WAY over the max. They still fit in the mag, but barely. The ONLY cartridge length i look at in load data is the minumum overall length. As long as you are not near max load, it is ok to seat the bullet touching the lands. Work up and watch for pressure signs.

DiscoRacing · December 14, 2010, 04:12 PM

In the boat with I C H....I have two calibers that I load that are nearly too long to fit in the mag.

frumious · December 16, 2010, 09:27 PM

I totally agree - when determining how far out to seat the bullet, find what the max COAL is for your weapon (based on what will chamber and what will fit in the mag). Then compare that COAL to the COAL listed for the loads you are looking at and decide from there.

I just went through this exact same thing with pistols. Definitely a light-bulb moment in my short reloading "career".

-cls

December 14, 2010, 03:09 PM	#1
Chinny33 Senior Member Join Date: November 30, 2008 Location: Los Angeles, CA Posts: 248	*Careful seating bullets according to COAL* Greetings, I was seating Sierra 85gr BTHP, for my AR-10 in 243win. According to Sierra's manual, it is supposed to be seated for a COAL of 2.650". I loaded 50 rounds with that COAL. It sat really nicely. As usual I double check everything and didn't realize that I completely ignored that I should check the throat dimensions in my rifle. So I used Hornady head space gauge and found out that my actual COAL should be 2.633" So, out of pure curiousity I chambered a round. Well, STUCKO!!!! Since I was careful not to let the bolt SLAM as it should, I was able to easily pull the round out of the chamber, noticing that the bullet was seated WAY too far forward. The rifling left small marks on the bullet, giving away that it is seated too far forward into the lands. I ended up seating the bullets to a COAL of 2.621" and BAM I have some super awesome rounds that will chamber and shoot accurately since they're seated close to the lands of the rifling. Be careful everyone. CHECK throat dimensions and not just blindly relying on manuals. You might end up really jamming a cartridge into a chamber and be in a whole world of mess where you have to shove a rod down a barrel on a LIVE round. Note, since we are hand loaders/ reloaders we have the liberty to load according to OUR preferences and OUR tolerances, not according to general factory standards. Most benchrest or competitive shooters will purposely load their cartridges so that the bullet will seat almost touching the lands of the barrel, giving better accuracy and consistency. Heck, why not? __________________ PLAN PLAN PLAN A prudent man forsees evil and hides himself; the simple pass on and are punished Proverbs 27:12 Last edited by Chinny33; December 14, 2010 at 05:13 PM.

December 14, 2010, 03:16 PM	#4
IllinoisCoyoteHunter Senior Member Join Date: December 23, 2008 Location: Southern Illinois Posts: 1,527	Good thing you checked. Some guys swear by jamming that bullet into the lands. I seat my Berger vlds .010" off the lands in my Savage Model 12 in .243 WIN... which puts the COL at WAY over the max. They still fit in the mag, but barely. The ONLY cartridge length i look at in load data is the minumum overall length. As long as you are not near max load, it is ok to seat the bullet touching the lands. Work up and watch for pressure signs. __________________ ~~IllinoisCoyoteHunter~~ ~NRA LIFE MEMBER~ ~NRA CERTIFIED INSTRUCTOR~

December 14, 2010, 04:12 PM	#5
DiscoRacing Senior Member Join Date: December 19, 2008 Location: milton, wv Posts: 3,640	In the boat with I C H....I have two calibers that I load that are nearly too long to fit in the mag. __________________ Desert Eagle Alliance Group Launcher Extraordinaire ______ ----Get Busy Live'n.....Or....Get Busy Die'n......Red -------They call me Dr. Bob,,,, I have a PhD in S&W

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December 14, 2010, 03:15 PM	#2
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,883	Suggest changing term 'head spacing' to that of 'throat dimensions' and you are right on.

December 14, 2010, 03:16 PM	#3
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	"According to Sierra's manual, it is supposed to be seated for a COAL of 2.650". Part of the "problem" is that so many people (incorrectly) think a book OAL is a "supposed to be seated" thing. It is not. It's only what the book makers used in their weapon to develop the data. But, their's isn't mine so I have to find what works for MY rig! And chamber headspace is measured from the bolt face to the shoulder, not the end of the leade/throat. Cartridges don't have headspace but they need to be sized to match the headspace.

December 16, 2010, 09:27 PM	#6
frumious Senior Member Join Date: May 13, 2009 Location: Carrollton TX Posts: 521	I totally agree - when determining how far out to seat the bullet, find what the max COAL is for your weapon (based on what will chamber and what will fit in the mag). Then compare that COAL to the COAL listed for the loads you are looking at and decide from there. I just went through this exact same thing with pistols. Definitely a light-bulb moment in my short reloading "career". -cls