# Fine tuning a load



## Fargus (Feb 13, 2006)

Although not totally inexperienced in reloading, one thing I have never really been able to do if fine tune a load to a particular firearm. I have been loading for a 300 RUM for several years now and guess I just got lucky because I found a load that that rifle liked after trying a few in the manuals. Now I have a 25.06 that I was not so lucky on and it's giving me fits.

Is there a way to determine what adjustments need to be made? Trying to be more efficient than just working up a load and trying it blind.


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## Ernest (May 21, 2004)

Its a multi-variable thing, so I try to hold as many variables constant as I can, and then try to change only one variable at a time. Easier said than done sometimes. 

I think first order of business is to select approriate components. Decent brass, decent bullets, and a powder that others have had sucess with for that round. Get it close with one of the approaches (ladder test, whatever) with one bullet, one powder, and one set of brass, and then make small changes to fine tune. Seating depth, primer selection, brass mfg-er, etc. 

(As an aside, in .308, my Hornady Match brass is significantly lighter than R-P brass. A water test would likely reveal a volume difference which, in some loadings, could be the difference.) 

Bigger picture - part of the problem here is the data sample size. Every single one of us likely has shot one of those wall hanger targets. You know, just a stunning group of three or five that we use for bragging. Often times, when that same load is shot over a bigger sample size, what at first blush appeared to be a hammer load, is merely so so in ten round groups or say ten five round groups. Ten five rounds groups tend to separate the only so so from the true hammer loads. 

(Add in the fact I'm a poor shooter, and I am truly doomed to burn thru a ton a ammo.)


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## Bantam1 (Jun 26, 2007)

Ernest pretty much summed it up. I noticed that a simple change to the primer alone can change my group size and velocity by quite a bit. 

I start with one type of brass that I have selected based on volume or quality of brass. I use Hornady, Federal, Winchester and Lapua. I picked up some Remington to try too. My Winchester cases are used for my 155 grain loads in the .308. I am loading 45-46+ grains of powder in these cases. They have a larger volume than the Federal for example, so this is why I use Win. I also weigh the cases and sort them for uniformity. 

Then there is case prep and sizing. I use a bushing type competition necksizer. All of my brass is different so why use one set diameter to size the neck? I typically run about .002" neck tension, so the inside of the neck is .306" for a .308 bullet. This helps with seating the bullets and typically does not shave the copper when seating, assuming you use a good seating die and debur your cases. 

I then determine my powder load range. I am loading .308 and .223 so I check more than one manual or website for load specs with the bullets I plan to use. 

I use primers that I have had success with like Federal Match, CCI Bench Rest and even Winchester. I'll pick one and start with that. My findings have shown CCI BR2 to work really well with Reloader 15. Federal 210M and WLR have worked really well with my Varget loads. I usually find a few different loads that group well and look good over the chrono. 

Once I establish my powder charge I play with different primers and seating depth to find that sweet spot. I have seen primers change my group size by almost .50 MOA and velocity around 30-50 fps. This is with the same case, powder and seating depth. 

Get something to measure the chamber on your rifle. Depending on what bullets you use will give you a rough idea of what the seating depth should be for optimal results. In my rifle Sierra bullets like to jump about .030-.040" to the rifling. With Hornady AMAX it likes about .20-25". I also use a comparator to measure my seating depth. Measuirng from the tip of the bullet is worthless in my opinion unless you are loading to fit in a magazine. Even then most rounds can be loaded for mag length and uniform by measuring with a comparator. I have seen bullets vary in length by .020-.030" from lot to lot. 

My shooting varies. Mose of the time I shoot decent, but I have bad days. Then all my load testing is out the window because I sucked that day.


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## Fargus (Feb 13, 2006)

So more or less, my original thinking was correct. There really isn't a whole lot of science to determining the best load. It is simple trial and error.


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## seattleman1969 (Jul 17, 2008)

Fargus, yes and no. 

First you limit the variables as much as possible, neck turning, weighing cases before and after prep, likewise with bullets, double weighing powder charges, etc. 

Then you start the trial and error. 

I had a .270 Win Ruger 77 that wouldn't shoot factory ammo for anything. Once I got my cases prepped and my dies adjusted for the correct seating depth that the rifle liked I could put nearly ANY bullet/powder/casing/primer combo together and it would shoot MOA. 

Start with consistency in everything you do in your reloading process. Be absolutely 150% Anal-Retentive about consistency. Get your headspacing and seating depth correct. THEN start experimenting with different loads. 

That will at least give you a head start! Otherwise the others covered everything.

Adding one other thing...

Keep a log of all weights and measurements when it comes to every single component and process in your reloading. It will make it easier for you to track changes/adjustments and see what causes things to change in your results.

This incudes the weight range you allow for your brand of cases/bullets, Bullet seating depth off lands, charges, primers, case measurements, number of turns with your turning tool/flashhole deburrer/case trimmer, etc, etc. Consistency!


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## davidb (May 10, 2006)

Most of the reloading manuals have good info on this. I'll repeat what the others said-Only change one thing at a time and keep good records.

It helps to have a baseline of accuracy with factory loads or generic accuracy loads to make sure the rifle is tuned up properly. Then you can go about fine tuning once you know no major problems exist and the barrel is broken in. 

Now I start by re-bedding a new rifle and a trigger job otherwise I will never know how well the rifle will shoot. Saves ammo and frustration too. If you have a bad barrel you could spend more on components before you find a good load then a new barrel would cost.


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## Bantam1 (Jun 26, 2007)

A chrono will help a lot too. I think I paid about $100 for mine. It has helped me a lot. 

You seem to have a good plan. Stick with it and have fun.


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## davidb (May 10, 2006)

Just reread your question. The book Ultimate Rifle Accuracy goes in to reading groups and load work up. See what factory loads do. Might post some groups the configuration can at times tell you whats wrong. Also good for wacky theories my own included.

Another trick is to place your new targets over an old one to get a composite group, sometimes 3 & 5 shot groups will be random but a 20 or more shot group may tell you something.

If it is a mechanical problem the sooner you find and fix it the more time,money and frustration you will save.


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## pg542 (Oct 9, 2006)

Excellent tips from everybody. As far as what I would try first????? I'll have to go with davidb's idea of bed and trigger work. First, you have to have a platform capable of the best accuracy it can deliver. Then start adjusting things at the loading bench. For me, the single biggest improvement in accuracy came from a good trigger job (or replacement) and a glass bedding job to insure perfect action to stock fit. Even quality aftermarket composite stocks with built in metallic bedding blocks will have the barrel lug cut too big and thus could benefit from a good bedding job. These 2 simple fixes alone on past rifles made so-so shooters into sub-moa rifles. Then you can try all the different (and effective) tweeks and adjustments at the reloading bench. As mentioned earlier, consistency is the key. Change only one thing at a time, and keep detailed records of the results. (good or bad). And be careful not to make drastic changes in any thing you do. Even a change in charge weight as small as 1/4 grain can make a significant difference. Working up a great load is time consuming and sometimes tedious chore. But when you see your group begin to close up with slight tweeks, then you know you're on the right track. Kudos to the previos posters, you guys are pretty sharp,,,,Jim


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## Ernest (May 21, 2004)

Good point on the composite group target thing. In that regard, I work up loads shooting the exact same target every time. (Red 2 inch diamonds, two per page, download from the web and printed out.) Thus, its easy to cut the page in two, overlay the targets, and come up with a composite. 

I actually was doing this last weekend. One result, on this particular load, a charge from 27.2 to 27.5 all had the same group center. As such, if one were to choose a middle load - 27.3/27.4 for example - minor variations in charge should not change average POI. In contrast, 27.7 had a very different center. So, perhaps one should not load at the very upper end of the node - 27.5 - because charge variations or temps could potentially change POI.


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## THE JAMMER (Aug 1, 2005)

Great point on the temperature Ernest. By the way this has been a fantastic thread- any reloader who doesn't read every bit of this is hurting themselves. There are decades of reloading experience represented in this thread.

Regarding temp. Accuracy is a function of consistent velocity, velocity is a function of pressure, pressure is affected by temperature. I can't tell you how many times I have developed a "great" load at 80 degrees. But shooting the same load at 40 degrees it opens way up. Several have said how important keeping detailed records is. Recording the temperature at which you shoot a load should definitely be part of that record keeping. We have to remember: apples to apples.

THE JAMMER


Ernest said:


> Good point on the composite group target thing. In that regard, I work up loads shooting the exact same target every time. (Red 2 inch diamonds, two per page, download from the web and printed out.) Thus, its easy to cut the page in two, overlay the targets, and come up with a composite.
> 
> I actually was doing this last weekend. One result, on this particular load, a charge from 27.2 to 27.5 all had the same group center. As such, if one were to choose a middle load - 27.3/27.4 for example - minor variations in charge should not change average POI. In contrast, 27.7 had a very different center. So, perhaps one should not load at the very upper end of the node - 27.5 - because charge variations or temps could potentially change POI.


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## Screeminreel (Jun 2, 2004)

Adding to the already good advice, I will throw in a couple of examples.

First something everyone should be familiar with. I picked up a second hand rifle, good name, a little rough looking, but had potential. It was a Sako chambered in .243, that almost looked like it had been drug back and forth to the deer stand, but the price was right so I took the chance. Got it home, and tossed it in the closet for several months. I finally got a bit of time and decided to see what it would do. After spending almost two full days and part of one evening cleaning it, I finally got a clean patch to come out. The whole time I was thinking bad things about myself for this investment.

After the cleaning, I mounted one of my cheapy scopes on it, went by Academy and picked up two boxes of the cheapest Winchester ammo they had. Not that I liked Winchester, but it was the cheapest at the time. Headed to the range with rifle and ammo and not very high expectations at all, but figured at worst I had a good donor action.

I bore sighted the scope with a target set at 50yds, and fired two shots to confirm, then swung it around to 100. After letting things cool, I fired a 5 shot group, and was very pleased with the following results,









After getting a new stock for it, I found that after the fourth and fifth shots will rise a bit showing that the stock needs a bit of releiving along the barrel channel. I knew this going into the load process but still in all it ain't shabby. Here was a work up I did using some 100gr Noslers, and Hodgdon Hybrid 100 powder right after it came out. 









During this I only changed the weight of the powder, everything else was left the same. The cases were checked and trimmed if needed, pockets were cleaned every load. As you can see as I went up in powder weight the groups spread out some and then closed back up. The bottom left two spots were the final load using two different primers, the spots on the right were for factory load verification and for fouling shots after cleaning the barrel. I cleaned ever 10 rounds, and before each of the bottom left groups. Each had on fouler fired and the barrel was allowed to cool to ambient temp.

Another example, I purchased a wildcat chambered rifle from a fellow on another board. He developed the loads, reamers, and did all of the rifle work. He also sent the load info along with the rifle as well as bullets to load it with. His data used 98 - 104 grains of W-870 surplus powder, which is somewhere just above coal on the burn charts. When the rifle got here it was early March and the temperature was in the mid 60's when I did the initial loads for it. Everything on paper, and shooting 1/2" groups at 200yds I was very pleased, heck I even got a couple of hogs that weekend with it. So a couple of weeks roll by and I am loading it up again to try it out at longer ranges, dump the loads in the big ol cases and touched one off, everything was different, the report was MUCH louder, missed the target, and couldn't get the bolt to easily opened. Thought I might have missed the charge a tad so I loaded another one which I weighed, I had simply throw the first from the already set measure. Same results. When I looked at the two cases, this is what I found.









Everything came to a halt right then and there, as I wasn't even up to the upper end of the load data, only the bottom, which other folks were using to form cases with. So after a week long effort between myself, th builder, and several others shooting this same rifle, I backed the load off some 6 grains down to 92 and got good results. Once we figured in the ambient temperatures, the humidity, static pressures for the area, it all added up to produce much higher pressure in my and my friends rifles than was showing in other folks who lived in much higher elevations, or dryer climates or both. We had to adjust our data for our areas espectively or else risk blowing things up in our faces.

Just examples of two different things that can work with you or against you when your working up loads. I much prefer thing to go like the first example, and I try my best to keep it that way.


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## Bantam1 (Jun 26, 2007)

There was a great article in one of the reloader or handloader magazines. The writer wrote a several page article on developing a load for the .308. He tried multiple cases, primers and bullets to find the "optimal" combo for the rifle he was using. Some of the results were surprising. He made charts showing how much the case, primer and charge can affect accuracy. He even tested the cases to failure. He did just pick one powder and stuck with that for the entire load development process. 

I'll try to bring it in and scan it. His optimal load was not that great in my rifle. However, the information he provided made for an interesting read.


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## Texas Jeweler (Nov 6, 2007)

One other variable we all have is how the barrel is cleaned. And how often between how many rounds.

Jsut FYI...


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## Bottomsup (Jul 12, 2006)

After 25 years of benchrest shooting and working up loads this is my opinion.

1. Clean the barrel !!!! If the gun is new clean every five shots. Get all copper fouling out.

2. A trigger job is the first improvement you can make. Second would be to float the barrel. Third is to bed the action. 

3. Let the barrel cool to ambient temp before firing the next round.

4. When you find any consistency in a load start working with it. Adjust powder, primer, bullet depth to see what may improve the group.

5. I will load the same piece of brass at the range to check for best powder, bullet and primer.

6. Mark the high side of the brass with a dial indicator so it sets in the chamber the same way each time.


Yeah OK I am anal about it but if you want to know what works? Precision shootingmagazine is a great source of info.


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## sylvan (Dec 26, 2007)

x2 with the order of Bottomsup except.... I tend to stick with the same primer and play more with seating depth. A big problem is that most rifles are not made to benchrest standards and are not designed to do what we think they should. - the fun is making them shoot. I still weigh, sort, trim and use the same case lots for store bought Rem 700's (probably over the top, I know) but only after the trigger, free floating and bedding, I get pretty stupid when mounting a scope as well. My focus is to take out as many variables as I can. My shooting ability is another matter, I'm sorry to report.
Interesting thread BTW ... blondes, brunettes, redheads.....


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