Procedure for accuracy development ?

[LAKEMASTER]

What steps do you take to figure out an accurate load?

I have 60 loads to test at the range soon. The only variation is powder charge.

Let's say _____ charge gives me the best accuracy, what should i do from there. ?

All my bullet seating touches the lands or just off of them. So would there be any benefit to backing off or seating deeper?

[tazman]

Since touching the lands and being just off the lands gives different starting pressures and ending velocities, I would back away from the lands 10-20 thousandths while testing powder charges. Once you find the best charge range(usually there will be a weight range of a grain or even 2 that gives good accuracy) start in the middle of this range and work with your seating depth to get your best result.
Usually there will be several powders that give good results. I know this makes for a lot of testing and expense, but you end up knowing you have your best combination.
Been there and done that several times. That's why I keep my partial bottles of different powders around.
Even then I will often stumble onto a great load by accident when trying a load from a different rifle.
I used the aforementioned system to work up a load for a hunting rifle(30-06) with 150 grain bullets. Last week just for grins, I tried a few of those in my bench rest rifle. Surprise. It shot great. very close to the match grade bullets. I now have a cheaper alternative to practice with since it shot to the same point of aim at 200 yards.
I have been reloading since the early 70s. There is always something else to learn.

[Hick]

I do it exactly like Tazman says and it works great (Learned it here from the experts). For rifle loads I use steps of 0.5 grain for my first sets of ladders, then refine from there.

[LAKEMASTER]

so, are you both saying i should undo the rounds i have made up ? that would really bum me out if i have to undo all the rounds i bagged and labeled.

[Themoose]

Shoot em' and keep notes. I often find out with 3 or 4 rounds that a load may not be a top candidate. I take the unfired ones and dismantle and save the components to build more of the better loads

[Preacher Jim]

I sometimes use different primers, after I get my load shooting and have worked my seating depth to find what shoots best in a barrel. I trim all rounds same lenth, then I true the necks.
I also check runout for bullet being seated in alignment to the bore.

[LAKEMASTER]

Shoot em' and keep notes. I often find out with 3 or 4 rounds that a load may not be a top candidate. I take the unfired ones and dismantle and save the components to build more of the better loads

I made 6 of each charge. i didnt wanna make 10 or 20 per and stomach the rest of the rounds if i knew they were bad...

[tazman]

I made 6 of each charge. i didnt wanna make 10 or 20 per and stomach the rest of the rounds if i knew they were bad...

Don't undo the rounds you made up unless you run into an over-pressure situation before you get to the heaviest loads. 6 rounds per charge weight is an ok place to start. I usually use 5 per charge weight, but that is just personal preference, not a requirement.
Keep track of group sizes for each weight of powder so you only repeat the ones that work well. If you seated your bullets to touch the lands, I would run them back through the seating die and make them a few thousandths shorter for the consistency. Only after deciding on a powder charge would I work at getting the bullet seating in it's best position.
Themoose made a good suggestion about sometimes being able to tell if a load is not working in just a very few rounds. If it isn't working you can certainly pull the rest apart after you get home.
You may want to repeat this process with a different powder and/or different bullets another day.
As Preacher Jim suggested, different primers can have an effect on group size as well as powder and bullets.
Also brass can make a big difference. Different brands are made differently and usually won't perform the same.
I won't go into brass preparation here. Lots of good information on the web for that. It can be quite complex and time consuming. Do a google search for brass preparation for match shooting. You can decide for yourself just how far you want to go with it. You can reach a point of diminishing returns there unless you are wanting every last and least bit of accuracy from your ammunition.
Best to start each testing session with a clean and copper free bore. 60 rounds shouldn't build up too much copper but I don't think I would go much further without a good cleaning.
Later you can test to see how many rounds it takes to put enough copper into the barrel to effect accuracy beyond acceptable levels. For now, you want best conditions and consistency.
I will often make a few extra of the lightest charge so I can use them for fouling shots and to get on target. I have had different loads be as much as 8 inches apart at 200 yards, particularly when changing the powder type.
I like to test group sizes at 200 yards. Group variations show up much more obviously there than at 100 with an accurate rifle. You just need to make sure you are doing your part consistently well.
Good luck on your experiments and please report back with your results.

[popper]

Depends on accuracy requirements. The above advice is good, but requirements for plinking, hunting or BR are different. Ability of the shooter is the largest variable.

[Smk SHoe]

I like to do my initial test at 100 yards. Once I am on paper with lightest load, Each group gets it's own tgt sheet. ( 8 1/2 x 11 looseleaf paper with caldwells dot in center). Then I keep the same point of aim. You can see how the groups look and see the gradual change of impact on tgt due to velocity changes. Also, each tgt gets ALL reloading data recorded on it. Date, weather, powder Lot#, etc. Then next reloading session I will work around what I consider the best group of the first day. If I feel confident of the data from the first day I may change powder charge and seating depth. I.E. 15 rounds with XX charge with 5 each of touching lands, .005 off and .010 off. Any rounds that don't seem to work, the rest get put in the fouling box. Lifes to short to pulldown a bunch of ammo. Once I feel I'm about 80% there, I will move out to 200 yards and start running everything over the chrono. At 90-95% there, I will start weight sorting bullets and sorting by ogive measurement. I have sorted a box of 100 bullets and when done had 6 groups of exact bullets as close as I can measure. This discipline can get exhausting but it is rewarding.

[Yodogsandman]

I'd normally try different powder weights first with several powders using 10 shot groups with the C.O.A.L. adjusted to show the rifling on the bullet nose. Then with the best group, I try backing off the C.O.A.L. in .010" increments until an increase in accuracy shows. Then try different lubes and amounts of lube. I don't switch up primers that much unless I have a problem using Winchesters.

[OS OK]

All this info your getting is spot on...'details, details, details'...the more you document for yourself the more information you will glean later when you have left the range. I have also a notebook that reflects this test and I can make note of any round as I shoot them, a round that I pull or push so that I can throw it out of consideration when I try to determine the best load to progress with from here. This is just the first round at dialing in the rifle 'node' and then to work it further with say...primer brand, COAL or change brands of cases, etc.


Here are some rounds I have prepared to ladder test, target left and how I prepared the ammo to the right. I like to color the primers with Marks-a-Lots to prevent confusion and also when I inspect the primers and cases closely for pressure I have the load identified by color.



192034
192035192036
These next 5 targets reflect a different test with 168g. BTHP's. Check the info on the target and you will see how much that a few tenths of powder charge will change the POI, point of impact.

The attached photo at the bottom is the load I chose for this combination.

*Sorry for the messed up pictures...for the life of me I couldn't get them to align properly.







192037All these shots were the best I could send them individually...one at a time as if your life depended on doing it correctly. Take your time and the rifle will stay cool and temp. won't be a factor. 192038If you use a tripod...this is my thought but, don't shoot off the hard bench surface as it will affect harmonics of the barrel. This may be extreme to some, but I made a little dirt box to place on the table to set the tripod on. About 2 - 3 inches of dirt that offers the tripod a more cushioned set...trying to imulate a prone shot off the deck. OCD? Yeah, maybe but it works for me.

*The sighter target lets me soot the clean barrel and have an idea whether or not I'm going to be on the paper before getting into the carefully prepared rounds. It's more important to focus on your sight alignment rather than to try to get into the bull...let the rounds group where they may...if you mess with the scope you will get the wrong picture of what your barrel is doing with the different loads.

There is plenty of info on the Y-Tube about harmonics and nodes, one of the best I can recommend is... TiborasaurusRex (https://www.youtube.com/channel/UCqymwlCbVwpMnSLrd-NAQJQ) and his Sniper 101 Series. SNIPER 101 Part 7 - Rifle Vibrations & Harmonics EXPLAINED - Rex Reviews (https://www.youtube.com/watch?v=h407yVskVeM&t=2s)

Ok...good luck!
charlie

*If I have been too simplistic explaining these things, please accept my apology. I am just trying to cover the bases without knowing if you have already 'been there, done that.'192039

[Harter66]

Working up .
I set up a nominal OAL, generally the longest suggested in my books or that will fit in the magazine or nominally chamber .
I try for 10 loads in the start/max window from 3-5 sources .
When possible , I shoot every work up load for group , over the Chrony and for function . What good is a one hole group at . 308 outside from your 223/556 AR if it jams ,FTF , FTE or fails to hold open ?
Big cases have big gaps , if I bided strictly by the above I'd have completely missed the load in a particular 06' that shoots .75 inches and never seen better than a 2" group .
When I took the 1 gr window of smallest groups I found that it was 5/10ths of a grain from 1.5 to .75 to 1.5 and right at a start load in 2/3 manuals . The 49-57 gr window with 10 loads would have stepped right over the top of this load at 10 for the window .
In half grain steps I had a small window to go back and load .2 gr steps in .
In all but 4 rifles I've loaded for actual touching the lands wasn't possible with the bullet securely seated in the case . So those adjustments have been far down the list of things to change . In several Savages the closer I got the less likely I was to hit the barn .
If I have a lot beyond the load I'll break them down if it 1-2 loads I just shoot it .
Of course the more you shoot a particular rifle the more you have a better idea of where to find a load and what influences it . Some want a slow powder off the lands others want something faster right on the lands . Some will want it the other way around . Then you have the one that won't shoot over a certain weight no matter what shape it is .

I can't count the 5 shot work ups that I shot 3 of and was "NEXT" or had a great thing going and the last 2 proved it or blew it .

More or less in the confines of the above I've worked 222 to 45-70 and found a load within 100 rounds for a particular bullet ,brass or powder . Once the first load is on the books you can generally know whether or not a particular is going to work within​ 20 rounds .

[Smk SHoe]

I agree wit OS OK, detail, details, details or Data, Data, Data. I have a couple bench guns that I was shooting a lot of when I first retired from the army, 4 1/2 years later, with very little shooting. I'm just moving into a job I can start shooting a lot more. Pulled out the three ring binders ( one for each gun), has the targets, load data, printed load data, round counts ( -4's for the Arty guys), and all pertinent info to start right back where I left off.

[Scharfschuetze]

Love a lot of the above responses. I can't add much more to the sum of all of them.

I do set a goal and requirements before the process of working up a load. Questions like:

1. Does it need to feed from the magazine? This will determine your OAL and will probably keep you from reaching the lands on most factory rifles. If not, well Katie bar the door as far as OAL.

2. Hunting, target shooting or plinking? Accuracy, powder burn rate and bullet design are factors here.

3. Required velocity? Cast bullet alloy and powder charge will get a review here and this is really a subset of number 2.

4. Powders available? I have a good selection of powder in the magazine, but I like to burn up the older lots as well as the powder that I have the most of first. Which powder will work with the bullet weight and velocity goal get answered here.

Once I've answered those questions I have a good idea of components to use. I usually don't take more than three test loads per rifle to the range at any sitting. I shoot in 10 shot strings for accuracy of the load and over the chronograph at the same time. Depending on the firearm and load, I'll shoot at either 50, 100 or 200 yards. 10 shots will give you a SOLID idea of what each test load will do. Three shot groups only give you an indication of ballistic uniformity and accuracy. The NRA uses five 5 shot groups in their accuracy testing of any given load. I like 10 because I'm a competitive shooter and most strings are 10 shots in the traditional courses of fire like the National Match courses. Once again, here is a goal of your load development.

Once at home, I can compare chrono and accuracy results in comfort and then make a decision on further development. A good chart with accuracy and velocity per extra grain of powder will tell you a lot about where you are at and how close you are to your goal. Keep good and accurate records so that you can return to that load at any time and reload it when it is needed.

Once I'm satisfied with a load, I may or may not try a different primer. Believe it or not, that will sometimes make a world of difference, but usually it changes things only slightly.

One proviso is to change only one thing at a time. The scientific method that we all learned about in Jr High School science class is very applicable here. Don't over complicate your process. The number of permutations between powder, powder charge, primers, crimp or no crimp, etc., can run into the hundreds and by the time you achieve or test them all, you'll be out of the lot of powder or primers and have to start over again. Be methodical and make your plan up before you load and go to the range.

Buy your powder, bullets and primers in quantities large enough to achieve your goal and then to continue loading it for a long time. I have standardized loads that I can load at the drop of a hat at any time to do what I want to do with most of my rifles and handguns. I know that they will perform with those tried and true loads, but I enjoy the process whenever I get a new rifle.

I'm a huge fan of long range shooting, so I almost always test my mid to full power rifle loads at 200 yards. If they shoot well there, they will invariably shoot well at the mid ranges of 500 and 600 yards, further for full power match rifle loads intended for Palma or NRA long range matches.

[toallmy]

When doing the latter testing from mild to wild , don't load the wild unless you see a reason to in the groupings leading up to it , doing this saves a lot of knocking apart loaded rounds . And 200 yards shows more than 100 yards is good advice .

[Pirate69]

Has anyone tried the Optimal Charge Weight Procedure? It is a round-robin approach of shooting a number of different charges in three shot groups. The groups are measured and plotted. If you are lucky with your selected charge range, you will see a sweet spot that is the point to perfect your charge. If I have done this correctly a pdf of a procedure shot at 300 yards will be attached. Here goes!!!!!!!!

[Bird]

What steps do you take to figure out an accurate load?

I have 60 loads to test at the range soon. The only variation is powder charge.

Let's say _____ charge gives me the best accuracy, what should i do from there. ?

All my bullet seating touches the lands or just off of them. So would there be any benefit to backing off or seating deeper?

LAKEMASTER, You may have things a little backwards with regards to backing off or seating the bullets deeper. The best way to start is to have the bullets seated to reflect the shortest cartridge OAL. Then when you find your best load, you can seat the bullets out further without the risk of increasing pressure until you touch the lands.
Neck tension in some cartridges can also affect accuracy with a given powder load.
6 rounds of each load can work but I prefer 8 initially. I start with the lowest loads, but only shoot a group of 4 before moving to the next highest load. After shooting the first four of each load, I kick in a couple of vertical moa, then repeat with the remaining cartridges. This allows me to settle down with the rifle if I am not shooting too well.
If you have the time at the range, take a few prepped and primed cases, powder, bullets and press to the range, then its easier to fine tune the load while you are there.
For longer ranges, velocity spread will prove to be important, sometimes more so than accuracy at 100 or 200 yds.

[LAKEMASTER]

I guess ill take these to the range and carefully shoot them. maybe ill have stumbled onto a 1 moa load ?! maybe ill be back to the drawing board.....................................


i should have asked this sooner

[Scharfschuetze]

i should have asked this sooner

You're on the right track now. Be methodical and have a plan. Don't try to do too much at one sitting. 3 shot groups are just a clue and not to be trusted.

Example:

3 shots at 200 yards with the Lyman 311041 in the 30/30 and the remaining 7 shots with the same load for the test, same Remington 788 rifle only a few minuets apart. Here are 3 shots that = 1" or 1/2 MOA and 7 shots that = 3.9" or almost 2 MOA. When I saw the 1" group through my spotting scope, I laughed and changed my target to finish up the test with the remaining 7 shots. I did that as I'll probably never ever see a 1" group again like that with this particular rifle and load because it was a fluke and not a valid representation of performance.

[LAKEMASTER]

what do you all feel i can learn from these already loaded loads ?

i mean, i still should be able to tell what charge area will best suit this bullet right ? since the variation is the charge ?

[country gent]

I put together my test loads and keep detailed notes as to conditions , performance, velocity and extreme spread or standard deviation. I shoot from a solid bench with bags and rests. Measure group sizes and make notes of horizontal and vertical spreads both. I test for the best groups and then retest again on a later date to confirm performance. 1 good group may be a fluke the same load performing on 2-3 diffrent days is a good load.

[tazman]

what do you all feel i can learn from these already loaded loads ?

i mean, i still should be able to tell what charge area will best suit this bullet right ? since the variation is the charge ?

This should give you a good idea of the most accurate powder charge for that particular powder/bullet combination. Measure your groups and you will most likely find that 2 or 3 have nearly or at least very close to the smallest group size. You could then work in the area around those loads to fine tune it using smaller load variations.
Sometimes a very small load change makes a lot of difference in group size.

[Love Life]

I always start load development with the bullet jammed when doing my initial ladders. Once I have the most accurate charge, then I'll work that charge with different seating depths. From there it's onto primers...

A comparator is your friend. First ladder at 300 yards. Follow on ladders at 400 and 500 yards.

Prior to firing a round brass is weight sorted by case weight, and then volume. There's more you can do, but the first couple steps will get most people where they need to be.

Only change one thing at a time. Introducing to many variables at one time won't allow you to know what does and doesn't work.

[runfiverun]

here is the secret to good accuracy.
1 start with a good barrel with a straight chamber.
2 start with a good bullet.
3 it don't matter a whole lot after that.
the rest is just tuning for the center of the barrels vibrations.

[Love Life]

here is the secret to good accuracy.
1 start with a good barrel with a straight chamber.
2 start with a good bullet.
3 it don't matter a whole lot after that.
the rest is just tuning for the center of the barrels vibrations.

That's not very high speed nor is it very low drag.

[LAKEMASTER]

here is the secret to good accuracy.
1 start with a good barrel with a straight chamber.
2 start with a good bullet.
3 it don't matter a whole lot after that.
the rest is just tuning for the center of the barrels vibrations.

I have the first 2

[LAKEMASTER]

This rifle will shoot 1.5" groups @ 100 yards With any jacketed ammo.

[Larry Gibson]

As mentioned it depends on the "accuracy" level required or wanted. For example if you want to shoot in CBA matches, shoot at 200+ yards or shoot small varmints at distance then a high degree of "accuracy (you're actually asking about "precision" of the load in the firearm not "accuracy" which is hitting the intended target) then you'll want the best possible accuracy that you, your firearm and your shooting style can use. However, if your talking about shooting for speed as in CAS with a SAA revolver shooting large steel plates not farther than 10 yards away a great deal of precision is not required of the load or firearm.

From the question "procedure for accuracy development" I'll assume you want the best precision possible from your rifle so you can shoot the smallest most precise groups and/or get the best score with accuracy. If that is the case then the 1st thing is learning how to cast, not a good bullet, but an excellent bullet. We all think we can cast good bullets and most can, it's not hard. It also is not hard to take the next step and learn how to cast an excellent bullet with no defects and very consistent weight.

For many years I thought I could cast excellent bullets and did use cast even in long range matches. However, it was when I got into shooting high velocity with cast bullets that I discovered the difference. I also discovered the difference even in milsurp rifles when I started shooting milsurp matches. I won the CBA Arizona State Military Rifle match last year with a M39 MN against the vaunted M1903s. I have since repeated wins with the MN. Prior to learning how to cast excellent bullets the same rifle would shoot 2 moa 10 shot groups all day long with what I thought were excellent bullets. Here is what the MN will do now with a 314299 once I learned how to cast an "excellent" bullet. Shooting for score not group. That is both "precision" and "accuracy" fired during a match.

192330

2 examples of "precision" at HV; here is the Lyman 311466 at 2614 fps (15 ft) and the NOE 30 XCB cast bullet at 2975 fps fired for group at 100 yards. It requires an excellent bullet to do this. A "good" cast bullet just won't cut it.

192331192332

All the previous suggestions are good for load development but for the best "accuracy" you must start with an excellent bullet. All the load development in the world will not make a good bullet shoot as well as an excellent bullet. Yes, good bullets can shoot pretty well, but you asked about accuracy development. If you want the best accuracy then you must learn to cast the best bullet........it starts there.

Larry Gibson

[LAKEMASTER]

Today was by far a horrible day@ the range.

Not only did gun Jam constantly due to coal being 0.130 off but my spotting scope decided to break.

So. The one thing i was able to figure/ confirm is that my gun likes 14 grains unique. Both my trusty ranch dog target loads and the lee 312-160 bullets were 2 moa @ 100 yards. ( no gaschecks on these )

Im really disappointed in myself for assuming my loads were ready to go.i guess the bullet i used to find my COAL was a lemon.

[Pirate69]

Larry,

Those are some nice groups. With regard to consistent boolit weight, what do you consider consistent? Plus or minus X.X grains?

[Harter66]

Today was by far a horrible day@ the range.

Not only did gun Jam constantly due to coal being 0.130 off but my spotting scope decided to break.

So. The one thing i was able to figure/ confirm is that my gun likes 14 grains unique. Both my trusty ranch dog target loads and the lee 312-160 bullets were 2 moa @ 100 yards. ( no gaschecks on these )

Im really disappointed in myself for assuming my loads were ready to go.i guess the bullet i used to find my COAL was a lemon.

If I had a dollar for every time my QC department let me down that way ....... Well ok it'll only buy a couple of kegs ....... but that is a pit fall of using the 2nds for for dummies .

This weekend I shot some big step work ups in a 30-30 . 32-34 gr , 6 loads , 18 rounds . 4" ,3" , 3 well over lapped , 9 more growing from 4 to 12".

I have an 1895G that walks as it warms up . I shot the 1st 5 of a 15 round proof load (for the work up load not to blow up gun in a proof test) in to a 1.5" from there it fanned out to a 4.5" x 3" pear shaped group .....

The 30-30 makes me all warm and fuzzy , a 70 yr old kids grade , truck gun that definitely fit the 1949 cheap seats definition and it shoots cloverleafs when you hit the load from a 30 cal representative of a 22 LR up through I don't know why or how that gets stable but it's enough to hunt heavyweight​s.

The 45-70 isn't a let down , I mean sure it would the cats if it shot a nice repeatable 1.5" every trip with a solid hunting load and slightly soft bullets . It doesn't it does however shoot a broad range of bullets and powders in multiple sets into a reliable 4" within what I would call a normal ranges for the rifles intended use . I'm sure that I will find THE load for it but in the meantime I have what I have and it does what is needed .

[bullseye67]

Good morning,
"What Larry said X2"
I "thought" I could cast boolits that were perfect.....sure could in pistols!! Started to seriously cast for a couple of 30-30's an old 94 lever and a bolt Savage 340. I cast up some 170 Lee FN boolits gave them a tumble and picked a load from the Lyman cast book. Loads all went bang....I think I have gotten better groups with buckshot!! Did some reading, thinking and cleaned the rifles really good..I mean cleaned, then did it again, then once more just for fun! Cleaning rifles that have always been firing jacketed bullets, and getting them really clean, makes a big difference. Then I did all the stuff you are supposed to do, slug, chamber pound, measured the free bore....just took more care and attention, not quite to bench rest standards, but close. Then cast some way better boolits, water quenched WW with 2% tin solder. Still sized and TL with Alox X2. Tried again and much better results.
Fast forward to today 10 plus years later, WoW does time fly!!
A cheap Savage 30-06 a friend didn't like and "loaned" it to me to see if I could get it to shoot. I shoot a low(1600fps) power load for gophers with the Lee 170 FP boolit. Kinda a hopped up 22 Magnum. I am now on molds #3. The first one I made into a plain base, the second one went AWOL, this third one is the best mold I have ever got from Lee, their new production is amazing! That being said, attached target is 10 shots 40 yards, I will test out to 100 yards as I plink a couple of gophers next week. The second target is the results of 6 311299's at 100 yards. This rifle shoots better with cast than it did with Factory ammo. When I first got it I cleaned it with in an inch of it life, took a bit out the barrel channel for a better free float, tightened up, re-torqued all screws. I then fired a test group with factory Remington 180gr. I had a part box and I didn't take a picture or if I did I can't find it? At 50 yards 10 shots were a hand sized group. The reason I got the rifle was it wouldn't reliably hit a foot square plate at 100 yards...after I shot at 50 yards I could see why.

[runfiverun]

LakeMaster.
I got a Remington 700 in 8 mauser that shoots 1-1/2" at 100.
it does it consistently, with more than 1 bullet/boolit weight.
it isn't what I would call accurate and the chamber certainly is not cut straight to the barrel.

some of my other rifles however are straight, have good chambers, and will shoot well.
those are the ones I put the effort into, I buy the custom mold, spend money on the brass, and get good foundry alloy for them.
I also tend to cast smaller amounts of boolits for them because the attention to detail when casting for them is pretty draining.

[Larry Gibson]

Larry,

Those are some nice groups. With regard to consistent boolit weight, what do you consider consistent? Plus or minus X.X grains?

It depends on the weight of the cast bullet to begin with. Most weight sort thinking those bullets that weigh the same or with a +/- will shoot the best. I've learned that while that method of selection will give better accuracy it will not give "the best". As I weigh each bullet I visually inspect the bullets first. Any visual defect, no matter how small, is cause for rejection. I then weight sort to eliminate those very light bullets that passed the visual inspection but obviously have a void inside. I then put the bullets into small plastic bowls of .1 gr increments.

I'll explain with 7mm to 32 caliber bullets of 150 to 220 gr as an example. Many who weight sort will kind of "graph" the bullets out by lining them up in tenth grain increments that are consecutively numbered and straight across the bottom. What you end up with is a "bell curve" shape of bullets. The curve starts out curving up, peaks out and then curves back down almost the same as it went up. The majority of the bullets in the curve will have a 1 to 1.5 grain difference in weight. There will be some that are much lighter and a few heavier. That is what you get with "good" cast bullets.

Using a quality alloy that will cast excellent bullets is also paramount. This is why straight linotype and #2 alloy are most often used. They give excellent and uniform fill out, consistency of weight with fewer defects. Some batches of COWWs will also if the antimony and tin percentages are sufficient and balanced. Alloys in these smaller caliber bullets that give a lot of shrinkage will never cast "excellent" bullets no matter how good they look. The reason is we can not control the shrinkage and where it occurs on each bullet. slight shrinkages that are in different places on the bullet are undetectable by visual or even precise measurement and they mean a slightly unbalanced bullet. Might not seem like much but at longer ranges of 200+ yards it is detectable on target by enlarged groups and poorer accuracy. Complete fill out in the mould and minimal shrinkage is needed.

Weight sorting the visual inspection passed bullets with "excellent cast" bullets gives a weight sorted curve that rises sharply and then levels off with several weights (three or four of .1 grain increment) having about the same number of bullets. The curve then falls sharply to just a few heavier bullets. There is no downward "curve".

When I got the 4 cavity NOE 30 XCB mould I ran this test with Lyman #2 alloy;

I cast 531 bullets

1.9% were rejected for visual defects

8.6% weighed less than 157.7 gr (some as much as 2 gr less that obviously had internal voids I could not detect through visual inspection)

3% weighed 157.8 gr

4.5% weighed 157.9 gr

5.9% weighed 158 gr

18.7% weighed 158.1 gr

19.3% weighed 158.2 gr

21.6% weighed 158.3 gr

14.7% weighed 158.4 gr

1.8% weighed 158.5 gr.

I then loaded 10 shots of each increment (157.8 gr to 158.5 gr) to test at 300 yards.

Test rifle was my 30x60 XCB. The NOE bullets weight 164 gr +/- when fully dressed and were loaded over 53 gr of AA4350 which runs 2900+ fps out of that rifle. The incremental test loads were fired consecutive by weight with the barrel cooled, cleaned and then fouled with 2 fouling shots prior to the next increment test. The results were then graphed out for a simple visual comparison.

192552

We see the lighter weight 157.8 and 157.9 gr bullets were not as accurate. The lighter weight giving indication to probable incomplete and inconsistent fill out and/or shrinkage. The "heavy" end of the bullets (158.0 through 158.5 gr) gave consistent accuracy (precision) at very close to moa at 300 yards. I have run this test several times and with cast bullets in the 150 - 180 gr weight range I select the heavy end of the weight sortment +/- .2 to .25 gr. With this weight range I use the 157.8 and 157.9 gr bullets for foulers and the 158.0 bullets for sighters. The 158.1 through 158.5 are then used in matches and other tests where precision is measured.

With other weight ranges I like wise run a similar weight sort test and select the heavy end of the weight sortment for accuracy/precision use.

Larry Gibson

[popper]

As Larry says, normal (bell) curve is OK, when you get most at the heavy end, Best. Proper, complete fillout.

[Pirate69]

Good info from Larry to use as a benchmark for weight distributions. My range is much to wide in a Lyman 314299.