Powder Choices?

[Ivantherussian03]

I am rethinking my loads. I am curious why a particular powder choice works better in a particular rifle? Can anyone explain that or is it a mystery. Is just a trial and error process?

[missionary5155]

I am NO ballistic expert ... the reading I have done basicly says the cartridge shape, length, diameter plus bore diameter and projectile weight and barrel length all influence the burn rate,pressure, and eventual cunsumption of the powder.
I would reason you know that also if you are rethinking loads. But I assume the manufactures make application suggestions because they have the instrumentation devices to do the testing accurately.
But then there is also that individual boolit launchers preference to certain loads due to all the individual factors that make up that item... barrel stiffness, lands, grooves, chamber dimentions, stock attachment, shooter involvment... and on it all goes to include all the peculiararities of the boolit, lube, seating and crimp if used but not to exclude paper patching should the loader be inclined to send secret messages downrange inscribed on 20# cotton rag or whatever parchment is available at the moment.
So to me in my simple form of approaching each boolit launcher... read, think, ask quetions, and then begin the experimenting. Sumpton is a gonna wurk reel good !

[Ivantherussian03]

I understand that much of it. I was wanting more-- I am starting to believe it is more art than science.
Thanks for responding.

Looking at your location we are worlds apart!! Be safe down there!!

[jonk]

I agree, it is an art more than a science. In THEORY it should be a science (ballistics is of course, a subset of physics) but no 2 barrels are the same. As said above, even 2 consecutively made barrels may have totally different preferences though identical in every respect.

That said, you are dealing with a lot of factors. Twist rate, barrel length, barrel flex/vibration, rifling depth and type, crown type, etc.

You need first a bullet that will stabilize at your desired velocity with your given twist.

Next you need a load that produces that velocity. Bullet profile and weight dictate this.

Suppose for instance you decide that you can stabilize a 150-180 grain bullet at 2000 fps. Common for a 1:10 twist .30. In theory- and I say in theory because I've done quite well with such loads- things like 10 gr of Unique or 13 gr of Red Dot will be too slow. Enough powder to generate this speed will also generate too much pressure. Something like SR4759 will get you there, just; 4198, 3031, or 4895 should do fine, as will any of the slower powders- so long as there is enough pressure to burn the powder efficiently. Then there is still the barrel harmonics to consider; the load might stabilize properly, but barrel whip might not be ideal to get peak accuracy. So still, work needs to be done.

Like I say, an art, not a science.

[Larry Gibson]

It is a science. The application may be an art to a certain point but the rest is science.

"no 2 barrels are the same. As said above, even 2 consecutively made barrels may have totally different preferences though identical in every respect."

I'm not so sure that is a fact, may have been at one time but not sure any more. I find more and more loads that shoot well in all barrels of the same caliber. I find that two barrels from the same manufacturer when chambered with the same reamer give idententical results, both with accuracy and velocity. I do find that two barrels from different manufacturers chambered with different reamers sometimes have different preferences, especially with loads using componants that are not normally used.

How is it that match ammunition shoots well in all good barrels. Taking for instance .308W match heavy barrels; how is it that with all the different makes, types of rifling, different dimensions and different reamers that they all shoot quite well with standard match ammo? I suspect a barrel with a defect may indeed have a preference. A thin tapered barrel most often needs a load that matches it's harmonics to shoot well. It is when we get out to the extremes of powder choice and bullet weight or design that we find "art" coming into play.

All of the above and any other reasons have pure scientific reasons for their accuracy or inaccuracy. The development of the load may be an art to a certain point but it to is mostly science.

Larry Gibson

[runfiverun]

i have also found that a load seems to work near as well in more then one rifle.
as long as the cases are near the same size.
i have noticed that with cast in particular that with cases of equal or near equal size that
they seem to prefer one of three loads i have figured out.
it may not be exactly the 28.5 load it likes best but maybe 29 but close enough to start with.
when i get a new one i try the 3 loads in them one will be a bit better then the others and i just follow it up.
you can usually have the rifle shooting as well as or better then j-words within 50 or so rounds this way.


but i have noticed that any rifle that seems to shoot remington factory loads the best will
absolutely not shoot anything else at all.....

[Scrounger]

It may seem like an 'art' but the 'art' is in the application. No two ways about it, it is a science like all physical things on this world. Some things just exceed our capability to measure, duplicate, or comprehend. There will be minute differences in the barrels (or some other part of the gun) that we are simply incapable of detecting. Ditto with the powder/primer/bullet/cases. A chronograph readily shows you the velocity (pressure) differences between consecutively weighed charges. Man's imperfection one again exposed.

[felix]

Art is applied science. That is the best way to describe what is being said. ... felix

[jonk]

I think felix nailed it.

To summarize my post into a short sentance: you can use science to predict what loads will work well and which won't but you never know until you try.... :-)

[wiljen]

Just as there are infinite shades of gray between black and white, so it is with burning rates of smokeless powder. Even within the same powder, those same subtle differences appear in lot to lot variations. It never fails that if I find a lot that works wonderfully, the store is sold out and no other lot behaves the same way.

[Ivantherussian03]

[QUOTE=jonk;389787]I agree, it is an art more than a science. In THEORY it should be a science (ballistics is of course, a subset of physics) but no 2 barrels are the same. As said above, even 2 consecutively made barrels may have totally different preferences though identical in every respect.

That said, you are dealing with a lot of factors. Twist rate, barrel length, barrel flex/vibration, rifling depth and type, crown type, etc.

You need first a bullet that will stabilize at your desired velocity with your given twist.

Next you need a load that produces that velocity. Bullet profile and weight dictate this.


Thank you very much that actually makes sense.:-D