| Posted: Tue Nov 17th, 2009 12:23 AM |
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ar15fanboy
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I am starting to reload for my 308 bot action. What is the best way to develop a load for my rifle. I will be using 7.62x51 case with varget as powder and Nosler competition 168 grain bullets. The load data for most 308 with Varget starts with 21 grains. I am planning to start at 40 grain of varget. How many rounds should I go with this charge and how many at the next step of charge and how big of a step in charge? I am planning to go as long as the bullet would allow with 1 caliber diameter in the neck. TIA.
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| Posted: Tue Nov 17th, 2009 12:46 AM |
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Dragon88
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First off, do you have a chronograph?
One note on the 1 caliber rule. With the 308 case and 168gr bullet, using a full caliber of bullet bearing surface in the neck (essentially the entire neck) will give you a COAL of only 2.750" or so. This is too short for best accuracy in most rifles. I use about .240" of bearing surface in the neck for a cartridge length of around 2.820" with that bullet. No issues with this at all and it provides good accuracy. Just something to consider.
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| Posted: Tue Nov 17th, 2009 01:22 AM |
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sdb777
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Do you have access to an 'automated' powder thrower(Lyman 1200DPS III or equivalent)?
I run my testing loads from start(manual data) to maximum(manual data) in 0.1grain increments(five rounds per weight thrown). Once I find the powder weight that seems to work the best, I start moving the projectile towards the lands/grooves to fine tune.
If you don't have a automated powder thrower, the 0.1grain could be kind of monotonous....maybe 0.3gr or 0.5gr would be better?
Scott (only change one thing at a time) B
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| Posted: Tue Nov 17th, 2009 01:32 AM |
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ar15fanboy
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I do have an RCBS chargemaster but no chronographs.
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| Posted: Tue Nov 17th, 2009 01:38 AM |
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OldStuffer
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Once I decide on a powder to load, I run typically from about 1/3 of the way above bottom (or all the way from bottom using GI brass, toward the max. load (a couple grains below max in GI NATO brass) in 1 full train increments. Typically 5 or so charges, 5 rounds each.
Then, I take the 2 best (tightest patern) loadings, possibly 3 if there is a "close run", and make that 3 grain or so spread in 0.5 grain increments, looking for the best pattern here. Again, typically 5 or so charges, 5 rounds each. Typically if, say, "42 and 43 grains were best", then I am likely to not just load those plus 1/2 grain split, but go 1/2 grain above and below, loading 41.5 and 43.5 as well.
Then, I go a load from the tightest group I get, (1/2 grain both directions) and load in 0.2 grain increments, again, looking for tightest patern. You guessed it, this loads 5-6 charges typically, 5 rounds each.
Oh, and, without looking at my loading data, if 21 grains of Varget is the starting load, AND YOU INTEND TO START AT 40, WTH is the Max-load????????
Don't know the relative density of Varget to WW748BR, but my GI 7.62x51 NATO brass typically only holds arround 44 grains of 748 by the time I work up a load. And that is usually flush with the top of the shoulder, but then, I don't compress Ball/Sperical powder, as it is not advised anywhere I ever saw. I have no concerns compressing extruded stick, but virtually all I load is ball or flake.Last edited on Tue Nov 17th, 2009 01:54 AM by OldStuffer
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| Posted: Tue Nov 17th, 2009 01:45 AM |
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OldStuffer
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The Hodgdon data I am loooking at runs from 42 grains of Varget to 46 grains (compressed) under 168 gr slug.
I would load 41 to 45 grains in GI brass for the first run, as I said.
All loadings for the seccond and third runs depend on the results of the first, and subsequently the seccond, runs.
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| Posted: Tue Nov 17th, 2009 02:24 AM |
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Dragon88
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I would reduce a little more. My testing with WCC brass shows that 1.6gr is the correct adjustment for IMR 3031. 2.0gr should be about right for Varget.
Since you don't have a chronograph, I wouldn't bother with doing a lot of little incremental loads. As long as you are blind to velocity, you would have to shoot many many groups to figure out that 42.X grains gives consistently better accuracy than 42.Y grains. Pick a mid-range and safe load that functions well and feels good in recoil. Then just shoot it, a lot. Shoot it on different days, in different temperatures, in no wind and in high wind. Get to know your bullet and your rifle. Experiment with different seating depths and such if you wish. After you get a feel for exactly what your load can do, then adjust the charge up or down slightly to test potential at higher velocity and lower velocity. You will be dying for a chronograph by that point and having one will help you collect a lot of good data. Just my two cents. Good luck and have fun! 
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| Posted: Tue Nov 17th, 2009 03:43 PM |
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scratchypants
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I try to not be swayed by tight groups alone and look more for similarities in point of impact. Once you find 3 loads in succession that produce a similar average point of impact, pick the middle group and begin tweaking. Last edited on Tue Nov 17th, 2009 03:44 PM by scratchypants
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| Posted: Tue Nov 17th, 2009 03:55 PM |
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ar15fanboy
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Should I be concerned if a couple of the primers went in without much resistance? Also, if I increase 0.5 grain between loads, is that too much of a difference?
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| Posted: Tue Nov 17th, 2009 06:21 PM |
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Dragon88
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As long as the primer cannot be seated by hand without a tool, and it doesn't fall out on it's own, it should be fine. Some brass has looser primer pockets than others. Loose pockets in brass that has been fired many times is a sign that it's nearing the end of it's useful life.
.5 gr is fine.
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| Posted: Tue Nov 17th, 2009 06:36 PM |
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ar15fanboy
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The primer is in there pretty good. I must have clean the primer pockets "too well". Thanks for all your commends.
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| Posted: Tue Nov 17th, 2009 08:14 PM |
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miestro_jerry
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If you have a suspect loose primer, I just paint the primer over with nail polish. I use what ever color of Sally Hansen's Hard as Nails. But I have had the need to do this for many years,
Jerry
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| Posted: Wed Nov 18th, 2009 03:06 PM |
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Don Fischer
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To develope a new load with any powder I start low and load to 1 gr over max in .5 gr increments. Those I use to determine the pressure limit's of my rifle with that powder and bullet. Fire one at a time and look for pressure signs.
Now I just recently learned of this thing called the ladder test. You load up one round each in half gr increments and fire them one at a time at a target. After each shot go down and mark each shot, 1 thru 7 say, when all the rounds have been fired, choose the three closest together that are in order fired. Maybe 1,2&3 or maybe 6,7 &8. Whatever it is, that's supposed to be the sweet spot to work around. The perfect place to do this is when your testing for pressure. I always have just fired those pressure shot's into the ground.
Let me know if the ladder test works for you, I've never done it. Rather after I have got my pressure loads done, I start in the middle and work up .5 grs at a time looking for the most accurate. Then I back off that load .3 and increase that load .3 trying to tweek the load. Lots of people also fool with the seating depth to tweek the load.Last edited on Wed Nov 18th, 2009 03:08 PM by Don Fischer
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| Posted: Thu Nov 19th, 2009 04:52 PM |
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ar15fanboy
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I am not sure if I can use the ladder test. I am not that good of a shot yet to rely on a single shot :( I will be loading 5 rounds of each load with 0.5 grain increment from 40.0 to 44 grains. My COAL is measuring at 2.825".
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| Posted: Fri Nov 20th, 2009 01:28 AM |
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scratchypants
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Also look up OCW - Optimal Charge Weight. That's what my method is based on. Be ready for some reading.
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xsmokex
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scratchypants wrote: Also look up OCW - Optimal Charge Weight. That's what my method is based on. Be ready for some reading.
Here is a link to it:
http://optimalchargeweight.embarqspace.com/
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smacks
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I would like to know where you got load data that starts with 21 grains of Varget for a 308. If you are loading a small case that fires a 308 bullet maybe. But The Winchester 308 smacks
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| Posted: Thu Dec 10th, 2009 02:39 PM |
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GarethM
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ar15fanboy wrote: I am not that good of a shot yet to rely on a single shot Neither am I,  .
Am busy working my way through a 1st attempt at using the ladder test, there is a spreadsheet there for calculating 20 loads (from the maximum downwards) and how things are progressing.
Hopefully I should get the 2nd part of the test worked on this weekend.
Gareth
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