Re: please help me with my .308 load
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TresMon</div><div class="ubbcode-body">okay, Here's an odd angle..
Start over and do it right, with a long range mentality, unless your never gonna Shoot beyond 200 yards. This will save you time, components & barrel life. IF you have a place to shoot at least 300(+)yards do a ladder test. 300 minimum, 600 is great, 1000yd ultimate, but it's easy for the wind to blow your hits off paper which knocks the test in the head.
1. Do a ladder test with three of the most popular/sucessful powders for
your cartridge/bullet. And while were on a long range forum talking about long range loads and accuracy, sell off all your 168's and never go lighter than a 175 in the future.
2.How do you do a ladder test? Glad you asked. Let's take say Reloader 15 powder. My Sierra manual states 35.8 is a start load and 41.3 is max. I like round numbers. So were gonna call it 36g. START, 41g. MAX.
3.Now you want to know what 1% increments of your MAX is. So we do the math; 41.0 x .01 = .41 So we are in this first course test jump .41 grains between each load. Again this first ladder is more course, so to save time let's bump it up to full half grain intervals, .5g.
4.No make a list of the loads you would load to have a single round from start, to max+ in .5 grain jumps. Write them down.
1.36g
2.36.5g
3.37g
4.37.5g
5.38g
6.38.5g
7.39g
8.39.5g
9.40
10.40.5
11.41g. BOOK MAXIMUM
12.41.5 !MAX plus!
13.42g !MAX PLUS!
14.42.5 !Max Plus!
<span style="text-decoration: underline">*** write the load number, powder type, and grains on each case of loaded ammo with a sharpie marker. For max and max plus loads i color the neck of the case RED.</span>
So now you have a mere LESS THAN 14 rounds to shoot and you will obtain VOLUMES of info. And to stop all the internet commando's from flaming me, let me say LOUD AND CLEAR
For shots #10 and on proceed with caution, looking and documenting well any signs of excessive pressure. STOP shooting when you detect the least sign of pressure: cratered primer, shiny marks on case head, Extractor/ejector marks, sticky bolt lift etc.Having max and max plus loads will let you know what the actual MAX load is for your particular rifle. My 300 win mag 1000yard rifle does not show pressure with some powders until I'm three full grain over book max. ANY loads deemed too hot to be safe to shoot should be pulled apart/unloaded right there at the range for safety reasons.
Shoot each load at THE SAME AIMING POINT. MARK each bullet hole by it's shot number referenced by it's powder charge after it's shot because you will have overlapping holes. Shoot one mark one. There are several ways of doing this whether it be shoot one and walk down and mark it, to really strong spotting scopes (always seems to screw up my ladder tests and I have to start over)DIY target cams, or coloring coding shots by coloring the bullet with a red,green & blue markers accordingly and shooting at white paper. The marker will transfer to the target paper. I'd still not shoot more than 3 before walking. Me?? No- I'd certainly not want it to ever be said I have a faithful & trusted shooting companion down range with a marker standing off to the side of the target board a safe distance and we "shoot one, mark one" as a expedient team.
So what's happening on paper? You will get a vertical string of hits. (don't worry if they shift left and right with the wind, that is irrelevant right now, trust me.) First thought is that it's increasing velocity that makes the hits climb up the target, and that is true to a point. What is also happening for the most part is the bullets are leaving the barrel in a different state of barrel flex, or vibration.
You need to understand this. When you fire your rifle, your barrel flexes in a sine wave pattern. What your getting in the ladder test is the bullet is exiting the muzzle shot to shot, with the barrel flexed more and more up.
BUT, ahah! you will get a few shots that cluster, or actually make a decent group on your target, despite their each one having a differing powder charge.
ENTER THE "NODE." The node is the very top of the wave and very bottom. For ultimate accuracy, you want your bullet exiting the muzzle precisely when it has flexed all the way up, STOPPED [for a nano second] before it begins it journey flexing back down. This is why you had a decent group or two during the ladder test, despite differing powder charges.
So now your looking at the ladder test target. You got shots all over the place vertically, but some formed nice clusters, or groups.
Note each powder charge that grouped. Let's say for this test, bullet holes 2,3,4 formed a group, and 7,8,9 formed a group.
So this is awesome. In a mere 11 or so shots, we learned at what powder charges the bullets actually leaves the barrel <span style="text-decoration: underline">when the muzzle is not moving(vibrating) around wildly.</span>
So now we go home sip a beverage and study and DOCUMENT our findings.
We see 36.5, 37 & 37.5grains shoot in the node of the barrel.
We now take these and do a refined but even smaller ladder test. (We do this for the other clustered shots too! Don't neglect to further ladder test any loads that formed a cluster/group.)
Let's jump in finer, .3grn increments now, we are refining things now. let's go a little outside* this accuracy window, powder charge-wise though just for good measure
1\36.3*
2\36.6
3\36.9
4\37.2
5\37.5
6\37.8*grains
So now we have a good lot of charges with overlap a little each way from the accuracy cluster of the first ladder test. we only loaded one of each charge again. Now go repeat the ladder test/target, and again in a mere 6 shots you will have volumes MORE information. [Don't forget to do this second ladder test for every accuracy cluster/group that showed up on the first test]For each ladder, it is optimal to back up at least another hundred yards from the last distance.
You will get another accuracy cluster, all the more dead-on the barrel's node. Let's say shots 2,3,6 again formed a group.
Now you go back and load 5 SHOT GROUPS for each of these:
5@ 36.6 grains
5@ 36.9 grns
5@ 37.2 g.
One of these will prove overall best. Now you got your load! And it is the LEAST sensitive to shot to shot velocity variations due to being on or near the node.
Now go back with this same powder charge in every round but play with bullet seating depth ladder test. Then if you want to be super anal,and can get out to at least 600yds. refine your powder charge by a .1 grain ladder test, then go back with a fixed powder charge, fixed bullet seating depth, and run primer brand testing too!
This is how 1000 yard bench rest loads are worked up & records broken. You may not choose to refine it to the n'th degree, but running 3, ever finer ladder tests as described here will get any rifle shooting as good as it practically can.
I just ran ladder test 1(course) and test 2 (refined) with my .300 win mag (FACTORY savage tac) I'm to where I need to move to 5 shot groups. But, for my 3rd and most fine/narrow ladder test I moved back to 500 yards. I fired two identical rounds to warm my bore and verify my point of impact on the 500 yard target, using a load from the middle ladder test that was already showing a good powder charge. My buddy who was not down range, not helping me from no where near the target board called back on the radio and said "Damn, don't change a thing, sighter shots 1 & 2 are within 3/4" of each other!!
I can't wait to get back to the range and run these final 5 shot groups, and then on to this weekends first 1000 yard f-class match in my AO with my new rifle.
This picture below was the last ladder test I did with my .300 Win Mag Savage Tactical rifle. Each shot was .5 grains hotter (H4831SC powder)than the last.
It's really easy to see exactly where the node is on this target. Shot 1-9 are in the photo but #'s 10 & 11 strung on up the target out the top, not in photo.
Remember that no two of these bullets holes where fired with the same powder charge, but <span style="text-decoration: underline">shooting in the node is where it's at</span>- the "four shot group" shown here, #'s 6,7,8 & 9 formed a 3.130" group or .63 moa group @ 525 yards from a factory Savage, with all differing loads. (And obviously in the picture- this was all from wind. I was disregarding and shooting right through wind gusts. There's only .949" of vertical dispersion here or .19 MOA @ 525 laser'd yards.)
Going back and trying my 5 (identically loaded) shot groups should theoretically at least shrink this by half, most likely quite bit more and identify my rifle's ultimate load with a 210 VLD bullet, and H4831SC powder. From what I have seen thus far with this rifle I'm looking for at least SUB(!) .35 moa 5 shot groups in the end. I'd sure take .2_ moa numbers.
Gentlemen and ladies, this is THE way to work up a load, and it won't even take a full box of bullets to do so.
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TresMon,
Like others have said Great write up! I could never have put it into words and explained it like you did here. I probably would have forgot to mention a step or two!
Guy's I will back TresMon's post 100%! I don't know him from Adam. But I have recently used this very process in using the ladder test. I will not use any other process! It saved me 100s of headaches and a lot less rounds fired with wasted components. Follow these instruction to the tee! You want be disappointed!
