:? Dumb Question, How much can you go at a time when you are trying to find your best OAL? I understand the part about using a dummy round and a sharpie to find the lands. I have just been going .10 over recomended oal. and things have been going fine. I loaded a few that just fit in the mag. Then I got to thinking maybe this would spike pressure?? I was at max Hornady load , wich seems perty safe. I seated them deeper like before and shot them. 1/2-3/4 inch group at 100yds 3 shot group. I have a .300WM M70, Classic, thumps a bit at the bench, but the lead sled helps that.
OAL ???'s
- Thread starter WnMag300
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DrMike
Ballistician
- Nov 8, 2006
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Welcome to the forum. I believe you'll find a wealth of information residing in those posting here and a ready welcome from some of the finest gun cranks in the world. There is no recommended OAL. What is published by reputable publishers is the SAAMI standard OAL. Your rifle may (likely will) vary. The closer to the lands, the higher the pressure, everything else being equal. The deeper a bullet is seated, the higher the pressure, everything else being equal. Since you are shooting a Model 70, you have quite a bit more room in your magazine than some other popular rifles, which permits you to seat the bullet out farther. The measurement you want to make is to find the OAL when the bullet engages the lands, and adjust seating depth from there. For cup and core bullets, a good starting point is 0.010 inches off the lands. For monolithic bullets, allow more jump to the lands (probably a minimum of 0.030 inches). Every rifle is different, and so the OAL of your round should be adjusted for the best velocity/accuracy. Seating out to allow more case capacity actually lowers pressure somewhat. Have a blessed Thanksgiving. Are you planning on doing some loading today?
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Thanks DrMike.
I made a dummy round coloring the 180gr Nosler Partion with a sharpie. Put the round in the gun and closed the bolt. I pulled it back out and can see the marks in the ink from the lands. The OAL measured 3.482 inches. So would I want to seat at 3.472 to start and go from there? I know the books say 3.340 for the sammi. This is were Im confused. I am guessing that I aslo would work up in these loads at a oal of 3.472 (if that is right). Thanks for the help.
I made a dummy round coloring the 180gr Nosler Partion with a sharpie. Put the round in the gun and closed the bolt. I pulled it back out and can see the marks in the ink from the lands. The OAL measured 3.482 inches. So would I want to seat at 3.472 to start and go from there? I know the books say 3.340 for the sammi. This is were Im confused. I am guessing that I aslo would work up in these loads at a oal of 3.472 (if that is right). Thanks for the help.
OU812
Handloader
- Apr 18, 2006
- 2,099
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WnMag300":k3k2ji9m said:
Will the dummy round fit in the mag box @ 3.472? If not, your mag box will be your limiting factor in the COAL. In all of my rifles, other than my 8mm rem mag, the mag box sets my COAL not my dist to the lands as they are greater in length.
Bill
DrMike
Ballistician
- Nov 8, 2006
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Bill is spot on. If the dummy round fits the magazine, your suggested measurement is correct. If the dummy round does not fit the magazine, you will need to load to fit the magazine and adjust propellant charge to look for accuracy. Generally, the magazine for the Model 70 is generous, allowing you to seat to a longer OAL.
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OU812
Handloader
- Apr 18, 2006
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WnMag300":323yzocn said:
May I ask why you would want a repeating rifle to shoot as a single shot?
I have yet to date not been able to get excellent accuracy using the mag box as my max COAL. To be honest until my 8mm came along I had never measured my COAL on any rifle. The only reason I did so with the 8mm was when I loaded a dummy round at mag box max my bolt would not close.
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OU812
Handloader
- Apr 18, 2006
- 2,099
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WnMag300":13m4bufb said:
Fair enough it's your rifle. Just saying you can shoot bug holes and still have a repeating rifle.
Bill
Yep, no harm in loading it like a Cooper!.. I haven't found it hard to get a rifle shooting at mag length or less though. I like to have the extra round on tap, but again, that is just my way, if your confident, no reason not to work with it. I would caution to not seat so long as to jam your bullets in the lands. That has been a pretty big headache for a few shooters. Scotty
Oldtrader3
Ammo Smith
- Nov 6, 2009
- 8,406
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It may not matter. I would find out where the OAL is the longest that will fit the magazine and lands. Then make up some loads there and at COAL and see if there is any difference. Several of my rifles shoot just as accurately at COAL as they do longer and this includes the .340 Weatherby with its .375 freebore. Hunting with using the magazine matters more to me than a little accuracy does. Longer is not always better.
CatskillCrawler
Handloader
- Jul 30, 2011
- 1,205
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Keep in mind that you will have a different OAL for each bullet type you shoot, disregarding mag length restrictions. A Partition, AccuBond, Interlock, and round nose will each have a different ogive shape. Very little of a round nose bullet will enter the throat before contact with your rifling lands occurs. A longer, thinner nosed bullet will have more of the bullet tip inside the throat before contact is made.
G
Guest
Guest
So far the advice you're getting is excellent. I'll only add my experience and let you judge for yourself. In all of my rifles, I measure max OAL for both the chamber (to the lands) and for the magazine (reliable feeding). I then start with the shorter of the two, and go .010" shorter if it's the chamber length I'm using. (Or .050" shorter if I'm using monoliths.) I've yet to have a rifle that won't shoot accurately at shorter than magazine length. Well, there was one Remington, but it wouldn't shoot accurately regardless, so it went down the road. But everything else will shoot at mag length or below. My most accurate rifle is my 270Wby, and I can't get close to the lands at all on that one. It's all about finding the harmonic node.
Good luck with the loading, and welcome to the forum!
Good luck with the loading, and welcome to the forum!
