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Old March 22, 2013, 04:57 PM   #1
pelo801
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OAL for 7mm08

I just started reloading for 7mm08. The load book tells me an OAL of 2.79 for the 120gr bullet I am using. I have some factory ammo as well. The thing is, the Winchester 140 gr power point measures out to be 2.64 to 2.62. This is the ammo I zeroed the rifle in with. This obviously isn't the same bullet I'm loading. But what gives, why is this factory ammo so short? and will the new loads I make with the lighter bullet and different OAL shoot to a completely different point of impact?

I have some other factory ammo. Some federal and hornady, and the OAL of those is pretty close to what the book says it should be for similar bullet types.
thanks.
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Old March 22, 2013, 05:56 PM   #2
Gster
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My Hornady data says 2.700 for 120 gr. bullet and 2.755 for 139gr. bullet.
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Old March 22, 2013, 06:12 PM   #3
pelo801
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The Lyman book says 2.790 for a 120 gr, 2.750 for 139 gr, 2.800 for 154 gr, 162 gr, 168 gr, and 2.735 for 175 gr. The 175 gr is a grand slam soft point, I don't know if that makes any difference.
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Old March 22, 2013, 07:55 PM   #4
Brian Pfleuger
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Quote:
I have some other factory ammo. Some federal and hornady, and the OAL of those is pretty close to what the book says it should be for similar bullet types.
What the book says about ammo length is irrelevant. If it fits in your magazine, feeds in your gun and you start at starting loads and work up while looking for pressure signs, you're golden.

That's half the point of making your own. It's for YOUR gun, not EVERYBODY'S gun. Factory ammo is for everybody's gun.
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Old March 23, 2013, 11:56 AM   #5
tobnpr
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What Brian said.

Every reloader should use an OAL gauge (buy the Hornady, or make one), a modified case (again, buy one or make one) to determine the OAL of THAT PARTICULAR bullet where it engages the rifling.

Then, you take that measurement with a bullet comparator- that measures from the ogive of the bullet, and not the tip.

Every bullet, and every chamber, is different.

Secant ogive bullets can be seated much longer (OAL) before they touch the lands, and accuracy is usually much more temperamental to seating depth.

Determine the length at which the bullet you're using touches the lands, subtract .01, and give it a "shot". Fine tune the jump after you've determined the best load for accuracy.

I use the 7-08 as my long-range rifle with the 162 grain Amax...it's a great caliber with impressive ballistics and moderate recoil.
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Old March 23, 2013, 12:19 PM   #6
wncchester
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"The load book tells me an OAL of 2.79 for the 120gr bullet I am using. I have some factory ammo as well. The thing is, the Winchester 140 gr power point measures out to be 2.64 to 2.62."

Yeah, all the OAL variations we see sorta tends to suggests maybe it's not something engraved in stone by the hand of the reloading gods, don't it?
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Old March 24, 2013, 08:08 AM   #7
PA-Joe
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Each manufacturer uses a different profile for their bullets. Some wider some more narrow. If too long the diameter of teh bullet wil touch the lands of the rifling. That is why round nose bullets have a much shorter COL. You can not interchange COL data.
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Old March 24, 2013, 08:14 AM   #8
onlybrowning
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OAL for 7mm08

Factory offerings are often made quite "short" so that they will chamber in all rifles in that caliber. I have not found OAL to be the end all be all, but feel it is important to find the length your specific rifle likes best with each load.
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Old March 24, 2013, 10:42 AM   #9
Brian Pfleuger
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Originally Posted by PA-Joe
You can not interchange COL data.
I wish the books didn't even have OAL listings. Anyone who understands the concept doesn't need the "data" and anyone who doesn't is just confused by it.

They should just say "fit and function in your firearm".

Any length that fits in the gun will be perfectly safe as long as we "Start Low and Work Up!", the reloaders creed.
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Old March 24, 2013, 04:24 PM   #10
wncchester
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Anyone who understands the (OAL) concept doesn't need the "data" and anyone who doesn't is just confused by it. ... They should just say "fit and function in your firearm".

Roger that. People should realize book OAL for any cartridge or bullet is no more a "specification" than book powder charges.
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Old March 24, 2013, 04:35 PM   #11
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Actually powder data is much more relevent , than published OALs . That was a poor analogy !
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