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Long Member
Joined: Dec 27, 2010 Posts: 37
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Ominivision1 Super Member
Joined: Sep 20, 2010 Posts: 2984 Location: Iowa
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Posted: Tue Jan 11, 2011 12:38 pm Post subject: Re: 30-06 rounds |
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Long wrote: |
well beer is ok, but here in WV my 150 proof white lighting will get u there much faster. very smooth |
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Dawgdad Super Member
Joined: Feb 08, 2006 Posts: 1065 Location: On the Prairie
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Posted: Tue Jan 11, 2011 1:06 pm Post subject: Re: 30-06 rounds |
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robd wrote: |
This is an interesting topic. When I use a dummy round to figure the max col in my .30-06 it is 3.449. No why can I load a round into the magizine at that length. I have found 3.367 to be the sweet spot for my rifle with 56gr of IMR 4350. So do the math and you'll see I am quite a bit of the riflings, but shot a 200 yard MOA today. I think I will stick with that now. |
OK Rob - you are new here so I will warn you right up fron, This subject I am getting ready to address has been a powder keg in the past but we have gotten past it and agree to disagree
The OA length you are measuring is from the head of the case to the tip of the bullet. The distance to the rifling of your barrel is not really related to that distance at all. Bullets profiles can be short and fat or long and pointy. Moving back from the tip which something less than .308", the part of your bullet that is first .308" is known as the ogive. The jump that matters in barrel harmonics and accuracy tuning is measured from the ogive to the rifling. The distance from the ogive to the tip will vary from bullet to bullet even in the same lot of match bullets (up to .012"!) but the distance from the base of the bullet to the ogive is very consistent on quality bullets (.002" max usually). To control this distance you really need to use a quality seating die and a comparator tool.( Hornady makes one) The seating dies do not seat from the tip but rather some point on the profile between the tip and the ogive.
Your rifles magazine will determine how far you can seat a bullet and still run it through the bolt in rapid fire. But if you single loaded you could load a longer bullet - up to the point where the ogive is jammed into the rifling and the bolt wont close. You have determined a sweet spot that gives you MOA results at 200 yards - that is great!
To make a guestimate of your bullet jump without a comparator you can loosely seat a bullet way too long and put it in the chamber and let the bullet be seated by the rifling. You will want a cleaning rod around as you will stick a couple of them in the rifling until you get it close. When you seat a bullet tha just gets some marks on the ogive measure that oal. Then seat the bullet in your seater die that you have set up from your 3.367" dummy. The difference in the se lenghts using the same bullet will be close tou your jump distance.
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Suzanne Super Member
Joined: Jun 27, 2009 Posts: 3323 Location: Eugene, Oregon
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Posted: Tue Jan 11, 2011 8:19 pm Post subject: Re: 30-06 rounds |
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Hey DawgDad that was the very best explanation I've heard!!!!
Suz
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Dawgdad Super Member
Joined: Feb 08, 2006 Posts: 1065 Location: On the Prairie
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Ominivision1 Super Member
Joined: Sep 20, 2010 Posts: 2984 Location: Iowa
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Posted: Wed Jan 12, 2011 11:24 am Post subject: Re: 30-06 rounds |
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Good drawing Dawgdad,
I know one match shooter out here that seats his boolits closest to the rifling as he can to eliminate any chance of wobble or whatever. Sure his is a custom gun, rifling and all that and it works for him. But on my M700 /06, if I seat the bullet closest to the lands, accuracy suffers. Every gun is an individual, and if you roll your own, you can find the sweet spot.
_________________ Regards
Limitations are but boundaries created inside our minds. |
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Dawgdad Super Member
Joined: Feb 08, 2006 Posts: 1065 Location: On the Prairie
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Posted: Wed Jan 12, 2011 12:11 pm Post subject: Re: 30-06 rounds |
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My match load likes a jump of .015-.010" - No more, no less. Outdside of that range, the groups grow.
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Long Member
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Aloysius Super Member
Joined: Nov 03, 2009 Posts: 2438 Location: B., Belgium
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Posted: Wed Jan 12, 2011 6:07 pm Post subject: Re: 30-06 rounds |
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because it's unguided. It can go up or down, left or right and not entering the barrel straight in the middle. And you cannot predict how he's going to jump next time because so many things influence its flight. So it might touch the lands before leaving the case, but you cannot predict what part of the bullet will hit them first.
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Northern Canuck Member
Joined: Sep 18, 2006 Posts: 72 Location: Alberta, Canada
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Posted: Wed Jan 12, 2011 6:20 pm Post subject: Re: 30-06 rounds |
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When I load 210 gr Berger VLDs in my 300 Ultra for targets I actually cannot put them in the floor plate of my Mod 700 LSS as they are too long, yet they do not touch the lands. For hunting loads there is no worry of getting them to touch on that firearm. Really depends on the gun and the bullets you use.
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tcknight Super Member
Joined: Oct 09, 2009 Posts: 327 Location: Arkansas
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chambered221 Super Member
Joined: Aug 17, 2007 Posts: 3455 Location: Lost for good !!!
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robd Rookie Member
Joined: Dec 19, 2010 Posts: 10 Location: Depoe Bay, Oregon
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Posted: Wed Jan 12, 2011 8:48 pm Post subject: Re: 30-06 rounds |
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Thank you Dawg.
I understand what you are saying and will work on that and post again when I have a ogive number and the number of the jump I am now using.
Thanks again.
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Dawgdad Super Member
Joined: Feb 08, 2006 Posts: 1065 Location: On the Prairie
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Posted: Thu Jan 13, 2011 8:47 am Post subject: Re: 30-06 rounds |
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Long wrote: |
why is it called a jump? is it because of a lack of a better term? since the bullet contacts the lands before it leaves the case. |
Not true grasshopper...when the powder ignites and pressure us generated inside the case it causes the mouth of the case to expand and release the bullet so the bullet is truly in freebore for a microsecond or two... This is why concentricity, neck thickness and neck tension of a round is important to the match and bench rest shoters so it releases uniformly and the bullet does not hang up on one spot or another and cause it to pitch or yaw off of the axis of the bore. (Also why a uniform crown is crital to good precison shooting as to release all of the bullet at the same instant.)
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