Hand Loading for Long Range 3: finding start OAL

Mar 1, 2010
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Virginia Beach
Re: Hand Loading for Long Range 3: finding start OAL

Tres,

I'm measuring the ogive length of the chamber of my new rifle iaw your method. Did it serveral times until I could get consistent results. My rifle is chambered in 300 WSM. With 190gr SMK bullets I measure the ogive lenth at 2.120. With 185gr Bergers I measure 2.128. There is a consistent difference in the ogive lenth. I thought that it was a fixed dimension and defined as the distance from the bolt face to the lands. I understand variance in COAL with bullet type but am at a loss to explain why the distance to the lands varies with bullet type. Looking forward to learning something else here. CJ
 
Oct 18, 2010
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Re: Hand Loading for Long Range 3: finding start OAL

I would also like to know the answer to Crazy Joe's post. I viewed the distance from the bolt face to the ogive as a fixed distance which should not change using different bullets of the same caliber. That should be correct unless you are not actually measuring to the ogive. For example a .308 barrel measures .300 diameter land to land and .308 groove to groove. My bullet measuring gauge has an inside diameter of .300. Therefore I'm not measuring to the ogive. I'm actually measuring a fixed distance away from the ogive and get a repeatable measurement with the same bullet type. Change the bullet type and the .300 diameter will most likely be at a different location. The result is different recorded measurements to the ogive if different bullet types are used.I think you would get the same length,bolt face to ogive,using different style or weights of bullets if the bullet gauge inside diameter is the same,in thousandths, as your barrel's groove to groove diameter.
 

TresMon

Gunny Sergeant
Dec 3, 2007
1,147
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NW USA
Re: Hand Loading for Long Range 3: finding start OAL


Crazy & Franklyn,

Each particular bullet weight has a bit of a different jacket profile. and even int he same weight class one bullet has a different jacket profile (shape) from the next.

So

let's say we're talking 300 Belted win mag., say 190 grn pills.

If it;s a hunting bullet, it will be less sexy (lower BC, less aerodynamic) and so the taper will be steeper on the nose of the bullet. This will make the riflings touch the bullet closer tot he nose.

But if we move to say a sexy 190 Berger VLD, or a even sexier JLK vld bullets the taper is long and gradually so the riflings will touch the boolit way back closer to the middle.

Hope that clears it up.
 
Mar 1, 2010
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Virginia Beach
Re: Hand Loading for Long Range 3: finding start OAL

Tres, I get the fact that different bullets will protrude deeper into the bore based on their profile and thus COAL will vary with bullet type. But chamber length is chamber length and determined by the reamer. It's should not be bullet dependent. Aren't ogive length and chamber length the same? CJ
 
Oct 18, 2010
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Re: Hand Loading for Long Range 3: finding start OAL

Thanks for the reply Tres.
In your example, both the 190 vld bullet and the blunt low bc bullet will both have a point on their profile where they measure e.g. .300 diameter, which in this example is the land to land diameter in a new .30 cal barrel. Let's say we want the cartridge length, measured from the cartridge base to the ogive(defined as the point on the bullet which measures .300 diameter), to equal the chamber length (defined as bolt base to beginning of rifling), I maintain that both cartridges measured from the base to the .300 bullet ogive will be equal in length. It doesn't matter that the .300 diameter is not at the same location on the two different bullet profiles. The seating die will be adjusted differently for each bullet/cartridge combination so that the cartridge length equals the chamber length. Both the vld and low bc bullets will be pushed into the cartridge neck different amounts but both cartridges will have the same base to .003 ogive length. I agree the vld cartridge OAL will be much longer than the low bc cartridge. Likewise, the low bc cartridge will have much more of its bullet submerged than the vld bullet. But they will both measere the same from the base to the .300 ogive.

I only state this out of interest and is in no way a criticism. Show me if I'm thinking about this incorrectly.
I found your reloading tutorial very imformative and helpful. I've made many of the gauges you described and incoporated the various techniques into my reloading.
Best, Frank
 
Mar 1, 2010
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Virginia Beach
Re: Hand Loading for Long Range 3: finding start OAL

Franklyn, could'nt have said it better myself. That is my theory exactly. My experience is different with Berger 185gr LDs and 190gr SMKs. Only explanation I can come up with is the Bergers have a gentler slope to the ojive diameter and experience less friction with the lands and so move a little deeper into the bore when measuring. Tres?
 
Mar 29, 2010
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Florida
Re: Hand Loading for Long Range 3: finding start OAL

I tried the Berger method to find the best seating depth in my rifle (ladder test from touching lands to jumping from .030,.060,.090 and .120 off the lands)and it hated the touch but would shoot to the same point of aim jumping anywhere from .030 to .090 off the lands.
Very forgiving ogive shape and easy to tune the Sierras and makes them less fiddly and sensitive than some VLD's can be.
 
Mar 1, 2010
93
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Virginia Beach
Re: Hand Loading for Long Range 3: finding start OAL

Thanks, I2D. I've heard that about the SMKs and may end up going that route. Just loaded up a bunch of Bergers seated touching the lands to test. New to the reloading game 200 rds or so under my belt and what to see for myself. Still interested in expalining why my ojive lenth (chamber length) measurements vary with the bullet.
 
Mar 29, 2010
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Florida
Re: Hand Loading for Long Range 3: finding start OAL

Also from what my benchrest shooter buddies are saying is that the new Berger hybrids are also as forgiving as the SMK's and prefer to jump and not as seating depth sensitive as the older VLD's due to the re-designed ogive shape and lots of the Berger lovers are switching over.
 
Jan 16, 2012
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The quickest way to find this sweet spot is to load ammo at four different COAL. Start with a COAL that allows the bullet to touch the rifling. The next COAL needs to be .040 off the lands. The third COAL needs to be .080 off the lands. The last COAL needs to be .120 off the lands. One of these COAL will outperform the other three by a considerable margin. It has been reported that the VLD bullets don’t group as well at 100 yards but get better as the bullet “goes to sleep” at further ranges. We have learned that by doing the four COAL test you will find a COAL where the VLD bullets will group well at 100 yards. Once the COAL that shoots best is established you can tweak +/- .005 or .010 to increase precision or you can adjust powder charges and other load variables. Frankly, those who do the four COAL test usually are happy with the results they get from this test alone. "" {Quote came from here}
I can't tell you how helpful this is... I have a GAP 10 in 6mm Creedmoor and I can't get it better than .75 MOA. I inadvertently changed the COAL on my .223 rounds an noticed a BIG difference. However had not idea how to do this in any consistent/predictable manner. Thanks again
 
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Feb 5, 2003
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Nope. Would be true if all bullets were shaped the same, but they aren't. Sometimes even the "same" bullet isn't - Example, I have a new box of 500 175 SMKs, and a ten year old box of 175 SMKs. I just now went and measured them. The old SMKs are .593 from their base to the ogive (using Sinclair's bullet comparator tool). The new ones are .585 from their base to ogive. So if I set my cartridge base-ogive length based on the new bullets, then loaded cartridges with the old ones, the seating depth would be .008" off, and I wouldn't know that if I didn't check every new box of bullets to make sure nothing has changed. Lots can vary .001-.002 from lot to lot if you're using mass-produced bullets like SMKs or Hornady AMAX/HPBTs.

I would also like to know the answer to Crazy Joe's post. I viewed the distance from the bolt face to the ogive as a fixed distance which should not change using different bullets of the same caliber. That should be correct unless you are not actually measuring to the ogive. For example a .308 barrel measures .300 diameter land to land and .308 groove to groove. My bullet measuring gauge has an inside diameter of .300. Therefore I'm not measuring to the ogive. I'm actually measuring a fixed distance away from the ogive and get a repeatable measurement with the same bullet type. Change the bullet type and the .300 diameter will most likely be at a different location. The result is different recorded measurements to the ogive if different bullet types are used.I think you would get the same length,bolt face to ogive,using different style or weights of bullets if the bullet gauge inside diameter is the same,in thousandths, as your barrel's groove to groove diameter.
 
Jul 30, 2013
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Lincoln, NE
Tresmon, first and foremost, incredible job here. Very helpful. I have just purchased a Savage 12 F T/R. I figured out my OAL from the ogive, a measurement of 2.236" with a 168 SMK will put me right at the lands. If I start load development jammed .008 into the lands, and I start at the bottom of the scale for powder weight, in what increments should I increase my powder? The Sierra book says 37.6 grains of IMR 4064 to start, and the max being 43.5. I know that being jammed into the lands is going to give me higher pressure and thus should be very careful when reaching max powder weight. Do I work up in .3 grain increments from the bottom? Is starting at the recommended charge still acceptable, knowing that I should expect higher pressures or should I back off of the starting point even more? Thanks again!

Adam
 
TT, if your happy I'm happy. However it's quite easy for the bullet to stick in the riflings on any "set back" method. I don't count on it being actual, even if you get "consistent" reading. How do you know your not getting consistent bullet set back & pull out?

If your getting great results down range, Go for it!
Tres
A friend of mine uses this method, and he uses a lighter to suit up the bullet, to see if there is any pull back. It works for him. Thank you very much TresMon for what you do for us!! Very much appreciated.
 
Feb 22, 2013
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Houston
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