Basic understandings?? aka miss information.

[searcher]

Reading it again: If you buy a Reloading Manual, a lot of the information you’re looking for is in there. Max loads, different powders, case fill, velocities, etc. Most of the work has been done for ya.

Well said....

 

[Medic505]

soag

Son of Another Guffy

 

[sailnaked]

What do you mean by 'I am attempting to understand the .270 and the .308 rounds'?
Are you just curious or is there some actual issue you're trying to address?

I am deciding what precision rifle I want to pay 2k for. not very many helpful answers, why would someone waste everyone's time commenting on the punctuation, and suggestions that a post is AI, if you have nothing to add just do that.

 

[sailnaked]

What’s a “soag “?

son of a gun.

 

[sailnaked]

I get suspicious of a brand-new account posting such a query on their first post..... but I will make a strong suggestion for their safety and then wish them well. It is my hope this isn't another troll.....

Since I can tell the OP has no physics, thermodynamics, chemistry, or ballistics background, it would be far safer for them to get hold of an internal ballistics program to play with while they read several chapters of ballistics textbooks to fill in that deficiency.

You can model propellants, bullets, barrel lengths, etc., to learn to get a feel for internal ballistics without the risk to your safety. Rookies should never attempt to do home experiments with dangerous high pressure such as found in ballistics. Good Luck. YMMV

I will give this post the time it deserves.
Wrong.

 

[okie]

soag

Son of Another Guffy

LMAO!!!

 

[Krogen]

I am deciding what precision rifle I want to pay 2k for. not very many helpful answers, why would someone waste everyone's time commenting on the punctuation, and suggestions that a post is AI, if you have nothing to add just do that.

I don’t see how your original post asks a question on what precision rifle might be a good choice. Instead it delves into ideas about internal and external ballistics. If you were to ask us a concise question rather than going on about your understandings, we could probably offer some good feedback. That’s why you got the replies that you did.

 

[jelenko]

I am deciding what precision rifle I want to pay 2k for. not very many helpful answers, why would someone waste everyone's time commenting on the punctuation, and suggestions that a post is AI, if you have nothing to add just do that.

Ah!
Can you say what you'd be using the rifle for? And, what is causing you to consider just 308 and 270?

 

[sailnaked]

my understandings are such
momentum(impulse) = mass X velocity,
more velocity means faster time to target and less drop at the target.
more push / velocity (accelerarion) in the barrel equals more velocity after it leaves the barrel. so in some sense more powder should equal more push.
now this is where it gets tricky:
smaller bullet will go faster if they have enough barrel and the powder burns fast enough.
heavier bullets will go faster because they get more push by the powder longer and they have more mass. (feel free to argue this but only partially what I am looking for.)
lets assume for this case that we want faster bullets and the ultimate goal is really fast really heavy bullets or a max of mass x velocity.
we can assume that the barrel is a fixed length, or somewhat the same.
I am attempting to understand the .270 and the .308 rounds. I have both and reload and shoot both.
the case for the .308 is smaller than the .270 so less powder.

is powder expansion rate (not defined by the specific barrel) related to burn rate or is it fixed (1grn of x powder expands 10.3 times at a faster rate than powder B that also expands 10.3 times) or maybe powder x expands to 10.3x and powder B only expands to 9.3x and takes longer) I am looking for a measure of force over time by powder. with the assumption that i can guess at the same barrel length and or bullet weight what powder will give me a higher velocity.

which brings me to the last part. the .308 has more space inside the barrel before the muzzle than the .270 so I assume I need a faster burning powder despite having more of it, to apply the same force on the .270 projectile.
but having more in a smaller space may be equal???

heres the real question: does 1gn of powder A expand to the same size as 1gn of powder B. I am looking to simplify not expand on burn rates. is it true that more powder burning longer in a smaller tube gives the same punch a less powder burning faster in a bigger tube. or is my head in a dark tunnel looking backwards.

i am currently running a test; same powder volume(full case) same bullet mass, (150) and different powder speeds. unfortunately I do not as of yet have a velocity meter so until I get one it is subjective.

some of this seems a little counter intuitive, faster powder in the .270 may be too much.
so for me the word accurate is inversely equal to the size of the group, more accurate smaller group.
best round to date was a .90 grn nosler, with imr3031 powder @200m. 3/4" group - that is one fast soag. this point may not fit my understanding. i think fast powder heavy bullet should be max impulse. but maybe fast powder light bullet equals max velocity. I look forward to hearing all about this.

wow, was hoping for a technical discussion of how the forces of powder act over time in an expanding cylinder, not comments on my spelling. I have been reloading for

 

[sailnaked]

my understandings are such
momentum(impulse) = mass X velocity,
more velocity means faster time to target and less drop at the target.
more push / velocity (accelerarion) in the barrel equals more velocity after it leaves the barrel. so in some sense more powder should equal more push.
now this is where it gets tricky:
smaller bullet will go faster if they have enough barrel and the powder burns fast enough.
heavier bullets will go faster because they get more push by the powder longer and they have more mass. (feel free to argue this but only partially what I am looking for.)
lets assume for this case that we want faster bullets and the ultimate goal is really fast really heavy bullets or a max of mass x velocity.
we can assume that the barrel is a fixed length, or somewhat the same.
I am attempting to understand the .270 and the .308 rounds. I have both and reload and shoot both.
the case for the .308 is smaller than the .270 so less powder.

is powder expansion rate (not defined by the specific barrel) related to burn rate or is it fixed (1grn of x powder expands 10.3 times at a faster rate than powder B that also expands 10.3 times) or maybe powder x expands to 10.3x and powder B only expands to 9.3x and takes longer) I am looking for a measure of force over time by powder. with the assumption that i can guess at the same barrel length and or bullet weight what powder will give me a higher velocity.

which brings me to the last part. the .308 has more space inside the barrel before the muzzle than the .270 so I assume I need a faster burning powder despite having more of it, to apply the same force on the .270 projectile.
but having more in a smaller space may be equal???

heres the real question: does 1gn of powder A expand to the same size as 1gn of powder B. I am looking to simplify not expand on burn rates. is it true that more powder burning longer in a smaller tube gives the same punch a less powder burning faster in a bigger tube. or is my head in a dark tunnel looking backwards.

i am currently running a test; same powder volume(full case) same bullet mass, (150) and different powder speeds. unfortunately I do not as of yet have a velocity meter so until I get one it is subjective.

some of this seems a little counter intuitive, faster powder in the .270 may be too much.
so for me the word accurate is inversely equal to the size of the group, more accurate smaller group.
best round to date was a .90 grn nosler, with imr3031 powder @200m. 3/4" group - that is one fast soag. this point may not fit my understanding. i think fast powder heavy bullet should be max impulse. but maybe fast powder light bullet equals max velocity. I look forward to hearing all about this.

Ok guys, thanks for reading my post, and thinking about it.
I was attempting to get to what would be a better target rifle at the furthest range. I ruled out the .338 lapua because of the price of the cartridges. (6$ ea). that left me thinking about the .308(shorter) .270 and the .300 win mag. I found a chart that expresses recoil and all things being equal that is for every force in one direction there is an equal and opposite force in the other direction, they listed the .270 as a 17 (no idea what the units were) and the .300 WM as 23 for the same 150Grn bullet, so that decided it for me. more punch on the same bullet for me is a better choice. the ballistics tables for these rounds were not clear enough for a decision. the .270 is faster and for the same weight a longer bullet, I was unclear on total energy. also the barrel for the .270 is 2in shorter?? the tables use certain powders, I do not have to limit myself to their charts. so I had the question what happens if you put a faster powder into a larger case with a heavy bullet. A. the gun flattens the case B. the bullet hauls bunny rabbits and is off the charts. PLEASE skip the im going to shoot my eye out comments. I know the limits and how to approach them with care.

 

[sailnaked]

Ah!
Can you say what you'd be using the rifle for? And, what is causing you to consider just 308 and 270?

max energy and range and stay in a tight group. needs at least a 150grn bullet. more likely 167-180

 

[jelenko]

What do you mean by 'max energy'? And, what range - in yards?

 

[mmcu]

OK, I am trying to help you here, so bear with me.

It sounds like you are looking for ballistic tables, kinetic energy calculators, point blank range calculators as well as free recoil calculators.

If that's the case, check out the following website. Simply input the variables and you'll get an answer that's close to real world performance.

ShootersCalculator.com

Online ballistic calculators to help shooters calculate bullet trajectory, bullet kinetic energy, maximum point blank range, and recoil. Explains how to make these calculations and produces charts and graphs that compare various firearm cartridges and firearms.

shooterscalculator.com

If this is not the information that you're after, then I've misunderstood what you're looking for.

 

[joshb]

Ok guys, thanks for reading my post, and thinking about it.
I was attempting to get to what would be a better target rifle at the furthest range. I ruled out the .338 lapua because of the price of the cartridges. (6$ ea). that left me thinking about the .308(shorter) .270 and the .300 win mag. I found a chart that expresses recoil and all things being equal that is for every force in one direction there is an equal and opposite force in the other direction, they listed the .270 as a 17 (no idea what the units were) and the .300 WM as 23 for the same 150Grn bullet, so that decided it for me. more punch on the same bullet for me is a better choice. the ballistics tables for these rounds were not clear enough for a decision. the .270 is faster and for the same weight a longer bullet, I was unclear on total energy. also the barrel for the .270 is 2in shorter?? the tables use certain powders, I do not have to limit myself to their charts. so I had the question what happens if you put a faster powder into a larger case with a heavy bullet. A. the gun flattens the case B. the bullet hauls bunny rabbits and is off the charts. PLEASE skip the im going to shoot my eye out comments. I know the limits and how to approach them with care.

You missed the 6.5-284, straight 284 and the 300 WSM. All good long range rounds.

 

[dellet]

Your questions are basically too vague to answer. If you sat down with something like quickload work up a load to prove your point one way or the other, it could be done. A quick example might be helpful.

Compare a 308 W, with a 30.06.
Same bullet, same powder and charge the 308 W will be faster. And with a certain powder have less recoil. To get the velocity up in the 30.06 you’ll need to add powder.

In a crude way, the burn rate of a powder changes with the size of the initial chamber the burning begins. So the 308 with a smalller chamber burns more efficiently, developing higher pressures, faster.

Recoil is largely based on muzzle pressure. The higher the peak pressure, the lower the muzzle pressure. So depending on the powder chosen above, you could end up with a higher muzzle pressure with the 30.06 than the 308. The lower peak pressure in the 30.6 due to poor load density can produce higher recoil at a lower velocity.

When you try to compare different bore sizes, it’s more complicated. Again the same powder and charge Pushing the same weight bullet, will produce a higher pressure sooner, and hold a higher rate of combustion longer, due to having a larger container to expand in.

Then when comparing bullets of the same weight, leaving the muzzle at the same velocity, with two different diameters, one will have a higher BC than the other. You could choose two bullets with the same BC, but what’s the point of that?

Changing bullet weights adds another variable. At some point from 0-1000 yards a 25 grain weight difference with a 200 fps muzzle velocity difference, the drop will flip flop. The heavier, slower bullet will have less drop than the Lighter faster bullet. So inside 500 yards will have a different answer than past 1000.

My favorite example.
300 Blackout, 11.5 grains 4227 . Drop comparison 50 yard zero in inches.
125 SST 1050 fps
100 yards -7
200 yards -48
500 yards -440

220 SMK 1000 fps
100 yards -7.5
200 yards -50.5
500 yards -425

Same powder & charge, almost twice the bullet weight, 5% change in velocity.

This was an experiment in manipulating the burn rate of a powder based on seating depth, load density, bullet weight. Gives an idea of what you can do with too much free time on your hands.

 

[Dgd6mm]

Where's Laurie? He can possibly make sense of this.

 

[wildcat3d]

Ok guys, thanks for reading my post, and thinking about it.
I was attempting to get to what would be a better target rifle at the furthest range. I ruled out the .338 lapua because of the price of the cartridges. (6$ ea). that left me thinking about the .308(shorter) .270 and the .300 win mag. I found a chart that expresses recoil and all things being equal that is for every force in one direction there is an equal and opposite force in the other direction, they listed the .270 as a 17 (no idea what the units were) and the .300 WM as 23 for the same 150Grn bullet, so that decided it for me. more punch on the same bullet for me is a better choice. the ballistics tables for these rounds were not clear enough for a decision. the .270 is faster and for the same weight a longer bullet, I was unclear on total energy. also the barrel for the .270 is 2in shorter?? the tables use certain powders, I do not have to limit myself to their charts. so I had the question what happens if you put a faster powder into a larger case with a heavy bullet. A. the gun flattens the case B. the bullet hauls bunny rabbits and is off the charts. PLEASE skip the im going to shoot my eye out comments. I know the limits and how to approach them with care.

If your choice is between a 270 and 308, I'd go with the 308 all week long..imo

 

[dgeesaman]

Where's Laurie? He can possibly make sense of this.

This isn't really a technical discussion yet. It's a communication issue - trying to figure out what the OP is trying to accomplish and to what end.

We all know there are dozens of cartridges and propellants that can be competitive at long range. I think it's safe to assume a basic math thought experiment is not going to arrive at a more optimal solution than decades of hundreds of shooters tinkering and testing in the Real World.

 

[Dgd6mm]

This isn't really a technical discussion yet. It's a communication issue - trying to figure out what the OP is trying to accomplish and to what end.

We all know there are dozens of cartridges and propellants that can be competitive at long range. I think it's safe to assume a basic math thought experiment is not going to arrive at a more optimal solution than decades of hundreds of shooters tinkering and testing in the Real World.

Exactly! I can learn just about everything I need and want to know from Quickload.

 

[searcher]

max energy and range and stay in a tight group. needs at least a 150grn bullet. more likely 167-180

If you further define "max range and energy" the folks on this forum could give you better informed input. Being that you are comparing the foot pounds of felt recoil between the calibers, a 6 BR or Dasher is fully capable of 1,000 yard targets with a 105-108 grain bullet AND small groups. Recoil is not even a factor with those. Those would be my choices over a .308. But it sounds like you want something a bit more powerful? The 6.5x284, .300 Win mag and others are much less expensive to shoot than the .338 Lapua. No doubt about it - the more potent a cartridge you get, as you noted - the stiffer the recoil. Since you are looking into this as a target rifle, keep in mind that most target rifles are on the heavy side - and those recoil charts would make one believe recoil is worse than it is. I worked up some loads for a buddy's .338 Lapua (a factory Savage which came with a brake). While you could feel much more blast, the recoil was no worse than my unbraked 7 MM Rem Mag. Personally, I'd not entertain the .270 as a target cartridge. Not that it isn't a fine cartridge - there are just so many that are MUCH better for targets, good brass, bullets, etc. I'm not so sure about availability of good brass for a .270, though others might offer suggestions if you go that route. You might also consider how long you might expect your barrel to last, if that might be of concern.