OAL?

jsthntn247

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Joined
Jan 14, 2009
Messages
722
I'm just getting into reloading and had a question about OAL in a 7mag. I took a couple of resized cases and put a bullet in them. I then stuck the case in my rifle and let the lands seat the bullets in the case. Each of the 3 times I did this game me 3.361". Am I correct in considering this my max OAL for this rifle? If so, I was thinking about backing off to 3.351 or 3.341 for my seating depth, which would put me .01 or .02 off the lands. Does this sound like a good starting place?
 

jimbires

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Mar 16, 2008
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1,761
Location
clearfield county , Pa
with you using a resized case you are jamming the bullet into the rifling . I use a fired brass case and just pinch the mouth a little bit so the bullet has to be pushed into it . I color a bullet with a sharpie marker . just start the bullet into the case and load it into the gun . close the action . eject the brass & bullet . put the bullet in the case until the scrape in the sharpie lines up with the case mouth . try this and see if you get a different measurement . I start close and work away . .010 should be a good starting point . if the bullet sticks in the bbl push it out with a cleaning rod . Jim
 

boomtube

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Oct 8, 2007
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Location
Mountians of SW NC, near Asheville
".. put me .01 or .02 off the lands. Does this sound like a good starting place?"

Yeah. Work up your charges slowly (.5 gr. at a time, at most) until you reach book max or see over pressure signs to learn what your max is. Then charge your load development rounds and test them, up to that max.

When you find the best shooting charge with that powder and bullet, load another series with that charge and test for best seating by going deeper in .010" steps until you find the best OAL.
 

tayhot

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Joined
Nov 26, 2009
Messages
169
Location
NM
Depends..... what bullet will you be using? I have loaded many cartridges in the 7mm and used many different bullets. If you plan on using a Barnes or E-Tip bullet, you want to be .05 to .1" off the lands. Even more if neccessary
 

lever-hed

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May 8, 2008
Messages
248
Location
Ohio
The theory it works. There are better methods of doing it, but note just because you are on the lands, it doesn’t necessarily mean you will be more accurate. Now, you should be aware of mag length as it can determine your overall length, this is more true of short actions though. You can buy a Hornady bullet comparator gauge that will attache to your caliper so when you have pulled the marked bullet out you can make an accurate measurement of your OAL TO OGIVE. This is more accurate of a measurement then to the tip. You can also compare what factory ammo measures (to ogive) and use that as a baseline, and move up from there. Obviously you must do the steps you noted for every bullet you want to work on, the best way is to find the actual dimension to YOUR RIFLE”S LANDS, and make sure you use the same exact gauge for all your measuring. You can do this easier if you have a RCBS Micrometer gauge which is a great investment IMHO. Good luck!
 

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