OAL/COAL Headaches

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gfanikf

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So I'm working on getting my bullet depth set correctly, and its been a pain.

Now Hornady says for the 30-06 .308 diameter 150 gr FMJ rounds to have a COAL of 3.185. I keep getting within .005-.015 of it. How important is I get it directly at 3.185?

The next thing is Lee lists for a bullet of the same weight and type a Min OAL of 3.250? I'm confused what is the difference between the two?

So I just want to resolve what variance I can have in COAL and also why the difference in COAL and Min OAL.

Once that's done I can start loading en masse.
 
"So I just want to resolve what variance I can have in COAL and also why the difference in COAL and Min OAL."

Forget book OAL. All it means is that's the length the book makers used to develop the listed data IN THEIR RIFLE. Your rifle is different and you are going to be developing your reload for your rifle; if you limit your loading to book specifics you may as well use factory ammo and forget the advantages of custom reloading.
 
Unless Lee says the bullet they used is specifically a Hornady, the OAL will not be the same.

Hornady bullets are slightly different shape then Speer bullets, or Sierra bullets, etc.

If your FMJ bullets have a crimp cannelure on them, seat to that and that is the correct OAL.

I keep getting within .005-.015 of it.
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You should have no trouble adjusting the seating die to get +/- .002" of whatever OAL you desire it to be.

Make sure you don't have the seating die screwed down too far and it is actually crimping the case mouth before the bullets are fully seated.

rc
 
ranger335v said:
"So I just want to resolve what variance I can have in COAL and also why the difference in COAL and Min OAL."

Forget book OAL. All it means is that's the length the book makers used to develop the listed data IN THEIR RIFLE. Your rifle is different and you are going to be developing your reload for your rifle; if you limit your loading to book specifics you may as well use factory ammo and forget the advantages of custom reloading.
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Well this is my first reload, so I'm trying to keep things as close as normal, at least for this run through. I'm not even sure how I would be take advantage of custom loading yet, I just want plinking ammo.
 
"Well this is my first reload, so I'm trying to keep things as close as normal, at least for this run through. I'm not even sure how I would be take advantage of custom loading yet, I just want plinking ammo. "

Okay, seat so the crimp groove is at the case mouth or use a factory round as a test gage. And, next time, say what you're really trying to accomplish.
 
rcmodel said:
Unless Lee says the bullet they used is specifically a Hornady, the OAL will not be the same.

Hornady bullets are slightly different shape then Speer bullets, or Sierra bullets, etc.

If your FMJ bullets have a crimp cannelure on them, seat to that and that is the correct OAL.

You should have no trouble adjusting the seating die to get +/- .002" of whatever OAL you desire it to be.

Make sure you don't have the seating die screwed down too far and it is actually crimping the case mouth before the bullets are fully seated.

rc
Click to expand...
I guess the question now is, as long as its SAMMI specs, if I'm close to the my bullets COAL, being off is an accuracy issue, but not a safety one, right?

I have had ones set to the crimp cannalure, but it still seems off. It's just really frustrating, because I got it to 3.180 at one point, but I didn't lock it right.
 
Most bullets will have inconsistent olgives which in turn creates the variance you are seeing when measuring off the tip of the bullet. And since the seating die contacts the olgive, that is what causes the variance in OAL off the tip of the bullet. Back when I first started reloading I noticed the same thing you are dealing with. It wasn't until I started measuring OAL off the olgive that I figured out why my OAL's were all over the place.

As for determining seating depth, all you need to do is seat a bullet long enough to contact the lands and then continue seating deeper until the bullet doesn't make contact and fits your magazine. Mark a bullet with a sharpie so you can identify contact marks easily. Once that bullet stops making contact, just go .010" or .015" deeper to allow for olgive variances on other bullets, and your good to go.

GS
 
Dont go below min oal. If bullet has cannalure, thats where crimp is. I dont worry about the .001 as much, i just check my measurements to the .01 that is more than sufficient for standard reloaders.

Use .001 measurements if your on Navy Seal Sniper squad.
 
Save yourself the headache and buy a OAL gauge from Hornady and measure your rifle and make the ammo for your rifle. This will put the bullet right up on the lans and grooves, measure it then back off 1 or 2 thousandths and you will see an increase in accuracy and concistancy.
 
Factory bullet production entails multiple machines with multiple dies. This results in a box of billets with six or seven different nose profiles. OAL is dependent on the seater indexing off the sides of the bullet nose, so any slight variance there will induce an OAL variance. What you are experiencing is normal.
 
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