c.o.a.l. help

What I did to find my OAL, was after I had fired some brass to my chamber, I neck sized them only. But just enough that you can put a bullet in the neck and it not fall out and is somewhat easy to push in, but still enough tenson. Then chamber the round in the gun and then when your taking it out, be careful not to push the bullet into the case anymore and then measure it and subtract .010, ten thousands, from that number and your good to go. But as long as you get the number after pulling it then you can go from there. I did it a couple of times just to be sure it was right. Sometimes the bullet will get stuck in the lands, but big deal. Here is the video to were I learned how to do this:
YouTube - Making a Overall Length Guage
or just search youtube for making a overall length guage. Hope that helps any.
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[ I'm trying to work up a 300 rum load with 200smk's. how can i figure the c.o.a.l. for this load??? ]

Find the point where the ogive contacts the rifling and seat a dummy round at 20-30 thousanths deeper. See if it will feed through your magazine. If it won't, seat deeper until it does. When you get something that functions reliabily, develp your load for that lenght.

Later, after you've found your most accurate charge, you may want to experiment with seating a tad deeper and shallower to see if you can improve accuracy.

Don't jam your bullets into the lands with that magnum round. That has too much potentail for raising pressures very high.
 
Does it matter if the OAL is greater than the maximum OAL published by the reloading manuel.


For instance my gun and magazine redily accept a round that is 3.315 inches. However the max OAL by Barnes and others is 3.290. I know we are talking about 25thou but does it matter?

Can I safely load out to 3.3 or 2.95
 
"Does it matter if the OAL is greater than the maximum OAL published by the reloading manual?"

NO

Allot of guys load out past what recommended length is and if it will not fit in the mag then single round load them.

Do like boomtube said and make a dummy round I do this for all my rifles. It is real easy to do. Take a piece of sized brass. Then put the bullet you are going to shoot in the case and run it up in your seating die just enough for the bullet to seat in the case neck.

Remember this is a dummy so no primer or powder. Put the round in you rifle feed it right into the chamber and close your bolt on the round. Once you extract the round it will measure at the COAL of your chamber for that bullet and brass
 
I had tried that a few times but it was hard to do with the barnes XXX bullet. The rings cut in the base made the bullet slide and slightly unstable.

Anyway I've taken my 3.150 round and loaded it a few times and remeasured it. It now measures 3.295. Ha. The neck was obviously not as tight as I thought but this is good because I don't want my 7mm round lying on the lands.

I guess I'll load out to 3.28 or so.

Thanks for the advice.
 
The book OAL is no more a "law" than the powder charges they list. It's just the OAL they used to develop the data for their guns. With handguns, it's frequently established by the crimping groove.

Since we must develop our own chages, using their data as a guide, our specific OAL differences don't matter any more than our barrel lengths IF we start low and only move up if there is no reason to stop. If the OAL works through your gun without excess pressures, you are okay.

It is uncommon for sporter rifles to shoot their best with the bullets touching the lands. I find a set back of .030" or more from the lands is usually better for accuracy.
 
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