Why do you start with the COAL you do?

[scott123456789]

Going through the 12 pages of .308 loads and people run anywhere from the factory spec 2.8" to into the lands a ways. What makes you choose the particular starting length you use when you develop.

Asking this due to poor OCW results and many suggested I was too deep when I started at what sierra suggested for COAL. No looking to improve but without a number of tools what should I consider on the next round of testing.

 

[taseal]

Re: Why do you start with the COAL you do?

Well many start with different COALs because some of us have reamed chambers and it might not be the same from someone else's custom chamber.

for example, my chamber was cut based on a specific COAL for a specific bullet. so That's why I load my ammo with that COAL.

before this, I found what my COAL was (on the stock barrel) by seating a bullet loosely in a case, then inserted it in the chamber and see where the lands of my barrel pushed the bullet into the case. This way I knew what my COAL was going to be if I wanted to sit my bullet into the lands. but I don't like that, so I backed off by .001 and called it my COAL.

now as far as figuring out why I went with that... well... it's a game. It's like asking 'well how come people use different charges of varget when they all shoot the 168 smk.... Lots of factors. case thickness, tightness of neck, tightness of chamber etc etc...

people 'tweak' it because some run good with the bullet seating in the lands, perhaps because of their powder charge/type. or they have a very small cocentricity problem and putting it on the lands helps. maybe they are .01 off the lands because their chamber is so damn long and they can't get any closer...

what you need to find out is your COAL using your own chamber and touching lands. then back off .01 and start there.... get the powder type and charge down, and lastly you can play with seating depth...

 

[flashhole]

Re: Why do you start with the COAL you do?

I suggest you try another bullet. My experience has been if you have a bullet that shoots fairly well within a load range you can reap benefits by playing with the COL. But ... if a bullet just doesn't shoot well at all after a ladder test no matter how much you tweak the COL it will still shoot crappy. You didn't give any details about the bullet or the barrel twist.

 

[Timo Turl]

Re: Why do you start with the COAL you do?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: scott123456789</div><div class="ubbcode-body"> What makes you choose the particular starting length you use when you develop. </div></div>

Magazine length constraints

 

[scott123456789]

Re: Why do you start with the COAL you do?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TJ.</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: scott123456789</div><div class="ubbcode-body"> What makes you choose the particular starting length you use when you develop. </div></div>

Magazine length constraints </div></div>

So do you start at mag length or some other calculation?

 

[taseal]

Re: Why do you start with the COAL you do?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: scott123456789</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TJ.</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: scott123456789</div><div class="ubbcode-body"> What makes you choose the particular starting length you use when you develop. </div></div>

Magazine length constraints </div></div>

So do you start at mag length or some other calculation? </div></div>

you go as far as your magazine will let you making sure you are not going to jam your bullets into your lands. mag length is more of a limitation than a starting point.

 

[Timo Turl]

Re: Why do you start with the COAL you do?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: scott123456789</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TJ.</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: scott123456789</div><div class="ubbcode-body"> What makes you choose the particular starting length you use when you develop. </div></div>

Magazine length constraints </div></div>

So do you start at mag length or some other calculation? </div></div>

Mag length for me is 2.85. It leaves me well off the lands so i start there with a light load and work up. If i want to load closer to the lands i cant use the mag and that doesnt work for me.