Science of preference

So there is alot of experimentation that goes into load development...from rifles to pistols...brass types, alloy, powder, charge weight, seating depth, crimp, primer type, primer seating depth, sizing dies, neck sizing only/FL sizing, bullet size, chber casts, bore slugs and a pinch of eye of newt and lizard tongue.........to name a few.

Question i have is why is there so much preference in a mechanical object like a gun? It's almost of they have feelings or are picky eaters like my 3 year old...

My hypothesis is that there are way too many minute factors in play with how barrel harmonics and internal ballistics effect the accuracy producing variables that it would equate to tomes of data for each rifle to factor into repeatable process...so much so that simple trial and error is the quickest way to accuracy we can reasonably get.

But...is that the case? Has anyone looked into the variables and given some thought to what causes individual gun preference? Even two identical rifles produce different outcomes with the same load (it may be closer than different makes ie. Rem 700 vs Savage 110 in same caliber... but it's still different)

What causes this and where should I read up to scratch this curious itch I have to look into?

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It's just like a lot of things, to get from bad to decent takes much less effort than to get from decent to good, and getting from good to excellent is orders of magnitude more effort.

The joy and zen of shooting is trying to repeatedly do a simple task perfectly when in fact there are layers of complexity and variability at play that make that a most unlikely occurrence without a significant investment of time and effort. Many will shoot the same given two comparable guns and different ammo, ones skill and focus have to be sufficient to make use of any additional benefits of ammo or equipment.

Never gave it much thought...I like General Motors cars , girls with red hair , revolvers , cast boolits , blue steel , leather , real wood (not laminate), Cajun cooking and lately Republicans. Don't know why , that's just the way God made me , no sense losing sleep over it .
Gary

There are so many variables that would write a sizable tome too. We dont always fully understand some dont even know they are all there. We just know there is a window of operating reliably and we need to tweek that window so that the guns and ammo will work reliably within the conditions they will be used.

Like barrel harmonics being affected by ambient and heat of combustion.

Chamber pressure influences from seating depth. Seating depth lowers pressures till you ball seat and spike the pressures. Temps alter burn rates that affect pressures. This rabbit hole is deep.

Some claim superstition, but i think it is more of our prefered starting point. That superstition gives us the confidence and dedication to stick to it till we figure it out because we knownit will work if we only try this.

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The study of internal ballistics and external ballistics have literally filled multiple books! Yeah, you can get a doctorate in it. Complicated? You bet.

It's voodoo, I tell you. A is A on Wednesday, but more like B on Thursday. And no, I don't drink.

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I've loaded enough different chamberings over the years, much of it is now second nature. From the case capacity and bullet weight and design for a particular bore size, I have a darned good idea of which primers and powder will work best. I seldom need to try more than two or three loads to have a rifle shooting into 1 1/2" at a hundred yards. A friend had been fussing with a rifle for two years trying to get it to shoot well. I'd been telling him if he would give it to me, I would find a load for it. He finally did, and I gave the rifle back the next day with a good accurate load. I think his biggest problem was behind the trigger with that particular firearm.

It’s a popular science. You can isolate variables, observe them, and study their effect on the system. You don’t need a degree, nor time on the CERN collider to do this, just logic, the ability to teach yourself, and care.

Some people are fascinated by this process. Others buy a box of ammunition every ten hunting seasons and ignore the gun between hunts. Whatever works.

I have a friend who actually burned out on load development and shooting. That’s all he was doing, and it just got stale. He sold a lot of his equipment, bought a Harley and took up Ballroom Dancing. In a couple years, the Harley was gone, the tux was in the closet and he was back to shooting, casting and reloading. Some hobbies grab you, some don’t.

As far as barrel harmonics go, it's all about tolerances. Take two bars of steel and machine them as close as you can to the same diameter and length. Heat treat both. If you suspend them and tap each one with a hammer they might even sound the same. Take a microphone hooked up to a frequency counter and measure each frequency and you would see that they do not have the same frequency of vibration in spite of you doing everything you can to make them identical. Now add in slightly different powder charge weight, different bullet weights, even if they weight the "same", slightly different burning rates between the two charges, etc. Look at everything bench rest shooters do in trying to chase a 0.000" group.

Kinda like racing, fast is expensive, REALLY fast is outrageously expensive! Getting a quality gun to MOA is not a real big deal, getting 1/2 moa is work and getting under.100 lots of work. I'm no longer into that kind of pain/fun. Hunting rifles need to be under 2 MOA with a good cast FP or HP. If the first load I try doez that, I'm done load development and on to working on the real accuracy issue, me.
I found that primers can have a tremendous effect on accuracy, but the bullet is the biggest piece of the puzzle and powder next. Cases the right length, and consisteny neck thickness are players. Weighing brass,uniforming primer pockets,and for that matter weighing charges are not on my agenda. Can't tell the difference in a hunting rifle from field positions. Everything has an impact but you nesd to focus on the major influencers first. If that gets me where I'm headed then all I need is shooting and getting to know the rifle.
That's fust me, others dote on getting the tinyist possiable group on the bench, it's all good either way. It's a hobby, we all enjoy different aspects of it.
Well I went down a rabbit trail. I think the differences between the load preference of two quailty rifles may come down to tooling wear/setup during manufacture. A fresh reamer will cut different as it wears thru it's usable life. That same reamer will be slightly different after regrind. Still in spec, but "different". It seems,in my experience that higher pressure rounds are more picky, more stress exaggerates the miner differences in fit finish and assembly tolerances. I have found that 308Win bolt rifles seem to shoot the same load more consistently than 7mm rem mag. Small sample of 5 308s and 3 7 mags, but something there.

And who is going to guarantee that the steel that two different barrels are made of is exactly the same? You simply cannot make two guns exactly the same. You can make them as close as you can, but there will be differences.
You can't even make two cartridges the same. Way too many variables.
A person just has to set their goals and work towards them. If your goal is perfection in equipment and loads, more power to you and go for it. I chased that for a while and could never really get close.
I got under .5 MOA at 200 yards consistently but not much if any better. I simply am not good enough. Either in shooting technique or in loading technique.
I still have a lot of fun shooting those accurate guns though. I am going to have to have the big one shortened and rechambered soon. The bullet is getting too far away from the lands and is nearly too long to load now.

One way to look at this is How many parts are there in a given firearm? Every part has a tolerance on size hardness material composition of its own. every part is fitted into this machine to work with the other parts. While the same maunfaturer springs strength may vary slightly, bores and fit may vary some and also squareness trueness of the assembly varies all affecting accuracy with a given load. Harmonics depend on pressures size and composition to maintain the same patterns.

What Ive found interesting is the factory match loads that perform as well as they do in as many firearms as they do. At one time the 308 load on the High Power line was LC brass, 41.5 grns IMR4895, federal gold medal primer and 168 grn sierra MK BTHP. This load shot good in almost every 308 from the bolt guns to M14/M1As to converted garands. Palma rifles are normally built to shoot a given load not built and a load found.

So help me think this through a bit...as I understand it...(in analogous language)

Tremendous force ...say whacking a piece of steel like an anvil with a sledgehammer hammer...rock and hard place. If that rock and that hard place are exactly the same each and every time...the force is exactly the same each and every smack there would be small but measurable differences even based off ambient temperature pressure and humidity...minute but small...

If we were able to put input devices all over the anvil or the hammer we could measure and amplify those differences on a graph where we could clearly see the trends or difference from one whack to the next or over a period of days or weeks...

Replace the hammer with many multiple more variables like case variations, primer variables, powder variables (temp here too), bullet tolerance, and of course the biggest variables the person behind the rifle...then replace the anvil with many multiple parts pieced together with variable tolerance (instead of one slab of steel like benchrest rigs) the tolerances start to stack on each other quickly...

And instead of scientific equipment attached to every part we have one data point of amplification...the bullet...it doesn't lie...and it is our out put from all those stacked tolerances that have become too many to realistically account for.

I think I'm tracking here - and it makes me even more impressed with .25 moa guns and especially more impressed with you guys that can get cast bullets at very fast velocities AND great accuracy...that is a tolerance stack like a circus performer spinning plates! (While juggling)



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Exactly right.

Thats why i am a firm beliver in repeatability. It doesnt matter if i accidently get a load that shoots clover leafs one day. It matters if it will do it everytime. Often the load that was amazing one day, doesnt work the next day. I keep testing and trying till get a load that will repeatedly perform at a realsitic useable level.

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It's quite simple - two identical firearms. . .aren't.

First issue is that they're made by humans, and not always the same humans.

Second, they're made on machines set up and maintained by humans, and not always the same humans.

Third, everything spinning on that machine is subject to wear.

Fourth, there are multiple machines involved in the process of making multiple parts, and each one is set up and maintained by humans, not always the same humans, and subject to wear at a rate appropriate to their own tasks.

Fifth, even when it IS the same humans, it REALLY isn't always the same humans. This is the difference in worker attitude based on the Monday/Friday and Old-Lady-Dumped-Me effects.

And all of that brings us to why gun parts are made to tolerance ranges, not absolute measurements, and why custom gunsmiths get paid to dial the mass-produced slop down to lower levels.

Bolt face, receiver face, receiver threads, recoil lug, action screws and crown are all surfaces that SHOULD be absolutely perpendicular to the bore, or at true 12:00, 3:00, 6:00, 9:00. They often aren't

Ideal barrel/receiver thread interface should be tight. . .like, turn the barrel in two threads and you can't wiggle the muzzle end. Custom cut, yes; factory churned, don't bet the farm.

Bore should be centered in the O.D. of the barrel. I've seen one come off a gun that wasn't shooting get cut down a couple inches, at which point (once the bead-blasted crown was gone, leaving a 90-degree cut) it became obvious the bore was maybe 15-20% off center on the muzzle end.

Then we must ask how those humans, and not always the same humans, did on the final assembly and inspection.

These are all things that, if done to extremes, can make a rifle an absolute train wreck, but more often make for "plus .0001" here, minus .0001" there" variability which is where the individual "personalities" from one serial number to the next creep in. Just pulling random numbers out of my keister, ponder a gun that has 50 parts, 100 machining operations, and 40 different humans (and not always the same humans) touching it from start to finish, and you'll start to get your answer.

the nut behind the butt is the biggest variable .some days i shoot very well, others very badly learnt not to blame my equipment ,weather boolit, load etc .

i was once an "accuracy nut". every gun that i own/owned was sub minute at 100 yards. i'd use bullets, powders, primers and brass galore to find a sub minute group. i would take hours and hours to find "my load". i was completely insane about my grouping.

i have gotten older(not much on the wiser part[smilie=l:) and i found that accuracy is not "it". i'm perfectly fine with a 2 - 3" group at 100 yards, although they go 3/4 - 2 1/2" group(variety of rifles). i hunt deer. i hunt them close up and in the thickets and woods. a 150 yards is a long shot, 30-40 yards and under is my cup of tea(or coffee, i love coffee!!!). thats a big reason of why i got in on cast boolits. the other is less recoil on my shoulder.

sure i could shoot deer 400-500 yards, but the hunter in me tells me not to. i am a hunter, not a shooter.

I knew a gunsmith that called all semi-automatic pistols females. There was no logic or reasoning to what they liked.
I think the same applies to rifles.