Advanced Marksmanship Does a longuer barrel help for 1 mile shot ?

[CygnusX1]

With accuracy being the same in small and long barrels.
With shooters able to hit targets at 1 mile with a 16 inch barrel.

Is there still a need for 26, 28....30 inch barrels ?
What about barrel harmonics ? Are they worse in long barrels ?

Maybe its getting late and I'm overthinking this......

Thanks for your coments guys !

 

[G-Dog]

Not sure if you are serious, or maybe I’m missing something.

All else held equal, longer barrels = more velocity. More velocity = more energy delivered More velocity = less drop, and lest in wind. Shorter flight times are more forgiving increasing chances of first round hits.

You may be over thinking harmonics. Once a good barrel shoots with a tuned load the rest is bullet flight math. A good load/node may be easier to find on a short barrel, maybe. Each barrel is different.

It all depends on your needs, and how you feel is best to optimize your shooting equation, weight, balance, etc. But long barrels (26-30”) are still here to stay.

 

[MarinePMI]

With respect, long barrels do not equal more velocity. Long barrels allow slower powders to be used, that allow higher velocities with shallower pressure curves.

Ideally, you want what ever powder being used, to be completely burned within the last inch of barrel.

While harmonics are tuned to a load (node), there are cases where barrel dwell time is a factor. You often hear this as "a gun/cartridge being `bag sensitive'". Usually with long barrels and subsonic loads; fundamental follow through becomes very important.

Because of ELR distances, follow through becomes even more critical (IMHO), due to long barrels and long TOF. That increased TOF allows much smaller inconsistencies to be seen, such as those induced by improper follow through with a exceptionally long barrel.

JMTCW....

 

[Milo 2.5]

With respect, long barrels do not equal more velocity. Long barrels allow slower powders to be used, that allow higher velocities with shallower pressure curves.



JMTCW....

With respect, you are proven wrong daily here. Here is 3 samples, 20" barrel, 26 &28". There is a 100% powder burn in the 20" barrel. The majority of the time, 2" more barrel equal more speed with no trade offs other than what extra barrel lengths do for maneuverability.
One popular case where people don't stray much from powder mainstays is the Dasher, so proof that faster powders can accomplish more speed with little side affects.

 

[MarinePMI]

I think you missed the point entirely, but whatever...

 

[Milo 2.5]

I think you missed the point entirely, but whatever...

What? The bulk of your post was about subsonic ammo in long barrels. No dwell time in rifles that can actually be classified as mile guns. Just because a 6.5 creed can hit a mile, does make it capable, just means it made the journey, on a nice day. Longer heavier barrels anchor a rifle, as solid as it gets.

 

[Rocketvapor]

I guess you haven't seen the 1 mile shots with the 224 Valkyrie
Kidding.
One thing I wonder about is rifle BALANCE for prone long range.
Everyone knows the balance point has to be right in front of the mag.
Set the rifle up on a bipod, bag roll, and a rear squeeze bag or rabbit ear bag.
Weight on the bipod and out past it would seem to establish a mass out where it would do good.
For a 22 pound rifle with lots of added weight at the rear just to bring the weight up helps but where should the weight actually be when you only shoot supported?

I've read articles where bipod attachment has an impact on performance. Would a more forward Balance point with the same overall weight help stabilize recoil?
Sort of like an extended bow stabilizer give a extended polar moment out in front of the angular force?

 

[Milo 2.5]

I guess you haven't seen the 1 mile shots with the 224 Valkyrie
Kidding.
One thing I wonder about is rifle BALANCE for prone long range.
Everyone knows the balance point has to be right in front of the mag.
Set the rifle up on a bipod, bag roll, and a rear squeeze bag or rabbit ear bag.
Weight on the bipod and out past it would seem to establish a mass out where it would do good.
For a 22 pound rifle with lots of added weight at the rear just to bring the weight up helps but where should the weight actually be when you only shoot supported?

I've read articles where bipod attachment has an impact on performance. Would a more forward Balance point with the same overall weight help stabilize recoil?
Sort of like an extended bow stabilizer give a extended polar moment out in front of the angular force?

Not sure, buy an arca rail and adj your bipod to be set on the balance point and shoot it at a mile and report back.

 

[Rocketvapor]

Stuck at 600 for a few more shots, then 1000, but when I get to a mile I'll post on every gun forum I belong to

What I'm trying to point out (totally unqualified) is pair-of-dimes with rifle setup seems to be based on weird science.
Take the barrel weight of an AR and free float. The barrel/barrel nut/float tube are a tightly coupled joint.
Each support the other.
Supporting the float tube at or just past the balance of the barrel/tube mass minimizes the weight (gravity) at the normal balance point (the pivot pin).
With a rigid upper/lower lockup and a stock that doesn't flex supported at the rear, is rear weight better than forward weight?

 

[DairyDictator]

I guess you haven't seen the 1 mile shots with the 224 Valkyrie
Kidding.
One thing I wonder about is rifle BALANCE for prone long range.
Everyone knows the balance point has to be right in front of the mag.
Set the rifle up on a bipod, bag roll, and a rear squeeze bag or rabbit ear bag.
Weight on the bipod and out past it would seem to establish a mass out where it would do good.
For a 22 pound rifle with lots of added weight at the rear just to bring the weight up helps but where should the weight actually be when you only shoot supported?

I've read articles where bipod attachment has an impact on performance. Would a more forward Balance point with the same overall weight help stabilize recoil?
Sort of like an extended bow stabilizer give a extended polar moment out in front of the angular force?

Seems to me you'd want the weight as far back as you can get it, and bipod as far forward as possible.

Lots of guys with heavy barrels put lead in the stock for balance.

 

[Rocketvapor]

I agree, lots put weight in the stock for balance.
Balance is important.
With the two support points being the maximum possible apart from each other how much weight does the mid point see?
Some put lots of weight up front if the sport allows it.
Imagine locking the forearm to a 40 pound rest (illegal in most sports).
That adds 40 pounds to the front. Look at unlimited class rifles. Not pew pew pew look alikes or hunting rifles you have to carry.

What would happen with a rear balance point with a lightweight front end when it goes bang?

 

[Milo 2.5]

Stuck at 600 for a few more shots, then 1000, but when I get to a mile I'll post on every gun forum I belong to

What I'm trying to point out (totally unqualified) is pair-of-dimes with rifle setup seems to be based on weird science.
Take the barrel weight of an AR and free float. The barrel/barrel nut/float tube are a tightly coupled joint.
Each support the other.
Supporting the float tube at or just past the balance of the barrel/tube mass minimizes the weight (gravity) at the normal balance point (the pivot pin).
With a rigid upper/lower lockup and a stock that doesn't flex supported at the rear, is rear weight better than forward weight?

I guess I look at like this, the greater the distance between the 2 support points, shoulder and bipod, the more stable the platform.
On the same principle of a short barrel iron sight rifle to a long one. Barrel length doesn't contribute to accuracy, but the distance between the sights favor the long barrel. Only stands to reason, if you have a long barrel, the farther out the bipod is the better off you are, you shouldn't have to hold the buttstock down, for now you've added another dimension to things.

 

[MarinePMI]

What? The bulk of your post was about subsonic ammo in long barrels. No dwell time in rifles that can actually be classified as mile guns. Just because a 6.5 creed can hit a mile, does make it capable, just means it made the journey, on a nice day. Longer heavier barrels anchor a rifle, as solid as it gets.

Easy there schmuckle nuts, it's early, take a breath.

My point wasn't so much subsonic loads per se, but rather, long barrels don't necessarily equate to more velocity. The amount and type of powder (burn rate), paired to an appropriate length of barrel and bore size are what determine velocity. Your example appears to be a single load shown across different lengths of barrel. My point was the other way around; in that bore diameter and cartridge size determine what (if any) powder is optimum for a given length of barrel, which then drives velocity. It's physics, plain and simple. An analogy is an airplane and a different lengths of runways. With a given amount of thrust (or engine) an aircraft at max weight needs a certain amount/length of runway to get airborne. However, if a bigger engine is added (or a bigger cartridge), it will require less runway because it is expending/transferring energy faster (burning a faster powder, or more powder with a bigger case). The airplane gains flight in a shorter distance, but with other associated costs (wear and tear to engines, less efficiency, etc.). Kind of like the barrel life on a 6mm Dasher and similar rounds that run hot, to achieve a velocity with in a certain length of barrel

The extended length of barrels also means there is a potential for longer dwell times if velocity is lower (hence my example of subsonic loads). We're talking one mile shots here, so obviously that is an extreme example.

Again, this is all physics, so unless you can magically bend the laws of physics, I'd say you are mistaken when broadly saying length of barrel automatically equates to more velocity, because...well, that's just bullshit.

 

[Milo 2.5]

Easy there schmuckle nuts, it's early, take a breath.



Again, this is all physics, so unless you can magically bend the laws of physics, I'd say you are mistaken when broadly saying length of barrel automatically equates to more velocity, because...well, that's just bullshit.

schmuckle nuts, LMAO, that is funny!
I fully understand that too long can create drag, one only needs to look at 22LR or 9mm carbines for that shit. I just said most cases benefit from more barrel length,, of coarse there is a point of diminishing returns. I am sure you shoot close to the same crap I do, and in most cases going from a 22" to a 26" barrel just results in free speed, all else being equal.

 

[MarinePMI]

LOL! Yeah, I think we're in "violent agreement". My wording can get jumbled first thing in the morning, when responding while having that first cup of coffee. My apologies for not being more concise. ☺

 

[Milo 2.5]

LOL! Yeah, I think we're in "violent agreement". My wording can get jumbled first thing in the morning, when responding while having that first cup of coffee. My apologies for not being more concise. ☺

All good, lol
I've been called a lot worse on here.

 

[Milo 2.5]

LOL! Yeah, I think we're in "violent agreement". My wording can get jumbled first thing in the morning, when responding while having that first cup of coffee. My apologies for not being more concise. ☺

Back when I first got into LR shooting, made a friend shooting a 7 saum, 28" barrel, it was sent off to be nitrided, it came back slow. 4" was cut off and the 100 fps gain in speed was achieved. I am not foreign to your argument.

 

[Tokay444]

Not sure, buy an arca rail and adj your bipod to be set on the balance point and shoot it at a mile and report back.

Yeah, I'll take my bipod as far away from the balance point as I can FTW, Alex.

 

[Rocketvapor]

I like discussions.
(even with name calling )
I like physics

Dwell time is not a linear relationship with barrel length.
Bullet be traveling faster towards the end.
Comparing runway length to powder burn is valid.
Thrust continues after liftoff just like hot gases keep pushing until the bullet leaves the barrel.
I shoot small cartridges mostly and my longer barrels are faster.
With factory ammo and a few different powders.

One thing to consider, I think, is a longer barrel needs to be more rigid to avoid flex due to harmonics.
Follow though is important with precision shooting, short range or long.
Lock time, dwell time and trigger pull affect where the bullet is going to hit.
Follow through until the bullet hits the target helps spot hits.

"Yeah, I'll take my bipod as far away from the balance point as I can FTW, Alex. "
Your bipod is part of the balance. Same for a suppressor.
A balanced "rifle" without those two items becomes unbalanced with the addition of extra stuff.
Shooters like a light weight bipod. Helps carrying the rig to the line, keeps you from violating weight limits. But, would a 10 pound bipod be better for stability than a 20 ounce bipod?

I wonder what a weight and balance analysis of a long heavy barreled rifle would show?
I'm probably wrong with all this. Drag racing boats and cars have rear biased weight.
Airplanes have the balance over the wings (bipod ? ).

I kept typing after you liked this post.
Might want to reconsider

 

[Milo 2.5]

I like discussions.
(even with name calling )
I like physics

Dwell time is not a linear relationship with barrel length.
Bullet be traveling faster towards the end.
Comparing runway length to powder burn is valid.
Thrust continues after liftoff just like hot gases keep pushing until the bullet leaves the barrel.
I shoot small cartridges mostly and my longer barrels are faster.
With factory ammo and a few different powders.

One thing to consider, I think, is a longer barrel needs to be more rigid to avoid flex due to harmonics.
Follow though is important with precision shooting, short range or long.
Lock time, dwell time and trigger pull affect where the bullet is going to hit.
Follow through until the bullet hits the target helps spot hits.

Right, discussing a fulcrum of a rifle not "linear" with OP's question either.

 

[MarinePMI]

All good, lol
I've been called a lot worse on here.

Honestly, "Schmuckle nuts" was a term we used in one of the units I served in, as a joking way to admonish someone. It started out as a "Hey there Mr. Snuffleupagus, hold on there a minute", and eventually morphed into "Hey Schmuckle nuts...". Meh...must've slipped out due to the early morning brain fog...

 

[Steel head]

More speed=less time of flight which also means less drop and wind.
short barrel for portability or long barrel to get more speed.
Everything is a compromise, what are you willing to give up.

 

[CygnusX1]

Not sure if you are serious, or maybe I’m missing something.

All else held equal, longer barrels = more velocity. More velocity = more energy delivered More velocity = less drop, and lest in wind. Shorter flight times are more forgiving increasing chances of first round hits.

You may be over thinking harmonics. Once a good barrel shoots with a tuned load the rest is bullet flight math. A good load/node may be easier to find on a short barrel, maybe. Each barrel is different.

It all depends on your needs, and how you feel is best to optimize your shooting equation, weight, balance, etc. But long barrels (26-30”) are still here to stay.

Wow !......Lots of exchanges while I was shoveling snow this morning
I started quite a good and informative discussion here !!

Yes G-Dog, I was serious when I asked this question (I'm new and just completed my 100 post) but I now understand that there is a valid place for long barrels in LR and ELR.

I got more info/answers than I expected and I will say that you guys know your shit

I'm impressed by the "Hide" community

 

[want2learn]

"schmuckle nuts".....i love it.
i'm learning so much awesome information on this forum

 

[lash]

"schmuckle nuts".....i love it.
i'm learning so much awesome information on this forum

Yeah me too. A good chuckle, that.

 

[lash]

Stuck at 600 for a few more shots, then 1000, but when I get to a mile I'll post on every gun forum I belong to

What I'm trying to point out (totally unqualified) is pair-of-dimes with rifle setup seems to be based on weird science.
Take the barrel weight of an AR and free float. The barrel/barrel nut/float tube are a tightly coupled joint.
Each support the other.
Supporting the float tube at or just past the balance of the barrel/tube mass minimizes the weight (gravity) at the normal balance point (the pivot pin).
With a rigid upper/lower lockup and a stock that doesn't flex supported at the rear, is rear weight better than forward weight?

Not going all grandma-neitsche on you and it might have been an autocorrect, but the term is “paradigm”. Still sounds the same, but is not.

 

[Rocketvapor]

Was on purpose, a dig for those that follow old assumptions.

 

[47guy]

anyone seen @Milo 2.5 ? i think he goes by schmuckle nuts sometimes too.

 

[GrayRyder]

I'm going with the opinion of the guy with the least misspelled words. In the case, MarinePMI.

 

[CygnusX1]

Wow !.....I just read this tread through and will stick my neck out with this reasoning:

Here goes !

A greater mv means shorter flight time and less bullet drop to the target.
A heavy grain bullet like 180g or more, would be less affected by wind all the way to the target.

A shooter would select the cartridge/bullet weight to stay supersonic beyond the target distance.

Would you then experiment with lighter loads like 150 or 120g to get even faster mv, even less travel time to the same target with less drop ?

All this while considering the effect of wind, air density, humidity.......on that lighter bullet ?

Lots of gremlins to tame !!

PS: Despite some missinterpretations up above, I also saw respect, humour, and camaraderey (sp ?)
Totally..but totally different compared to Youtube comments where a difference of oppinion immediatly results in downright insulting comments making it impossible to continue a learning exchange.

Good people here !
Very enjoyable time spent in the Hide

 

[Milo 2.5]

anyone seen @Milo 2.5 ? i think he goes by schmuckle nuts sometimes too.

WTF, I was the one making sense and got called schmuckle nuts, no justice in this world, lol

 

[lash]

Yeah, but we all got to say schmuckle nuts multiple times, so fun was had by all.

 

[want2learn]

i think it's meant as a complement....
good thing he didn't call you a schmeckle

 

[47guy]

WTF, I was the one making sense and got called schmuckle nuts, no justice in this world, lol

I couldn’t help it...I’ve never even heard schmuckle nuts I just like saying it lol!

 

[b6graham]

There's a reason FTR guys shoot 30" barrels. And it's not weight or contour at shank

It's free speed when you know what you're doing

Shooting 200.20x and 208LRHT from a 308. There's scenarios when it makes sense and works

And theres times when the speed isn't worth it like hunting

Lots of people are moving to 27 and 28 inch barrels in the BR based cartridges. 30-60 extra fps fo freeeee

 

[Mk32784]

My next ELR gun is just limited by what fits in the biggest pelican case I own lol. Since I need to fly with it.

 

[_Raining]

Would you then experiment with lighter loads like 150 or 120g to get even faster mv, even less travel time to the same target with less drop ?

Those lighter bullets have a higher muzzle velocity but lower BC: ballistic coefficients (How well it cuts through air). So they will slow down at a faster rate then those heavy bullets. The biggest problem is going to be wind, drop can be calculated for easily but wind can not.

In general, heavier bullets have higher BC. There are exceptions like those fancy lathe turned solid copper bullets that are light and have a high BC. Shape also matters, a stubby bullet vs a sleeker one can weigh the same but have different BC's. But if we are talking the same type and shape, heavier = higher BC.

Let us look at some 30 cal Berger bullets:
30 Caliber 175 Grain Very Low Drag (VLD) Target
G7 BC: 0.262

30 Caliber 185 Grain Juggernaut Target
G7 BC: 0.284

30 Caliber 200.20x Hybrid Target
G7 BC: 0.328

30 Caliber 215 Grain Hybrid Target
G7 BC: 0.354

30 Caliber 230 Grain Hybrid Target
G7 BC: 0.368

30 Caliber 220 Grain Long Range Hybrid Target
G7 BC: 0.369

Here we see that in general, higher weight = higher BC but we also have an improvement in design that has caused the 220 grain to have the same BC as the 230. BUT, I would never run the 230 from a 308 Win because I wouldn't be able to push the bullet fast enough to utilize that extra BC to make it out perform the 200.20x, but from a 300 PRC I would be able to get it moving fast enough were it would overtake the 200.20x. So it isn't as simple as higher BC = best bullet for my cartridge. But in general, you want to go as heavy as you can while keeping the MV (muzzle velocity) fast enough to make use of the advertised BC.

I am not 100% confident in my understanding of this but IIRC, BC is not static, it is a factor of MV.

Anyway, this stuff can get really complicated so the easiest thing is to look at what other people are doing. If I had a 32" FTR rifle I would shoot the 200.20x's. If I had a 24" 11.25 twist 308, I would probably run 185's max. Which reminds me, you also need to make sure your rifles twist rate is sufficient for a particular bullet.

 

[b6graham]

Those lighter bullets have a higher muzzle velocity but lower BC: ballistic coefficients (How well it cuts through air). So they will slow down at a faster rate then those heavy bullets. The biggest problem is going to be wind, drop can be calculated for easily but wind can not.

In general, heavier bullets have higher BC. There are exceptions like those fancy lathe turned solid copper bullets that are light and have a high BC. Shape also matters, a stubby bullet vs a sleeker one can weigh the same but have different BC's. But if we are talking the same type and shape, heavier = higher BC.

Let us look at some 30 cal Berger bullets:
30 Caliber 175 Grain Very Low Drag (VLD) Target
G7 BC: 0.262

30 Caliber 185 Grain Juggernaut Target
G7 BC: 0.284

30 Caliber 200.20x Hybrid Target
G7 BC: 0.328

30 Caliber 215 Grain Hybrid Target
G7 BC: 0.354

30 Caliber 230 Grain Hybrid Target
G7 BC: 0.368

30 Caliber 220 Grain Long Range Hybrid Target
G7 BC: 0.369

Here we see that in general, higher weight = higher BC but we also have an improvement in design that has caused the 220 grain to have the same BC as the 230. BUT, I would never run the 230 from a 308 Win because I wouldn't be able to push the bullet fast enough to utilize that extra BC to make it out perform the 200.20x, but from a 300 PRC I would be able to get it moving fast enough were it would overtake the 200.20x. So it isn't as simple as higher BC = best bullet for my cartridge. But in general, you want to go as heavy as you can while keeping the MV (muzzle velocity) fast enough to make use of the advertised BC.

I am not 100% confident in my understanding of this but IIRC, BC is not static, it is a factor of MV.

Anyway, this stuff can get really complicated so the easiest thing is to look at what other people are doing. If I had a 32" FTR rifle I would shoot the 200.20x's. If I had a 24" 11.25 twist 308, I would probably run 185's max. Which reminds me, you also need to make sure your rifles twist rate is sufficient for a particular bullet.

Trajectory Normalizing Factor

patriotvalleyarms.com

FTR? 208 LRHT are gonna be a thing

longer barrel. free speed.

 

[hlee]

"Pair-of-dimes?"

 

[Rocketvapor]

Yes I know the correct term,
and that's what many follow instead of accepting newfangled sheet.

 

[CygnusX1]

Those lighter bullets have a higher muzzle velocity but lower BC: ballistic coefficients (How well it cuts through air). So they will slow down at a faster rate then those heavy bullets. The biggest problem is going to be wind, drop can be calculated for easily but wind can not.

In general, heavier bullets have higher BC. There are exceptions like those fancy lathe turned solid copper bullets that are light and have a high BC. Shape also matters, a stubby bullet vs a sleeker one can weigh the same but have different BC's. But if we are talking the same type and shape, heavier = higher BC.

Let us look at some 30 cal Berger bullets:
30 Caliber 175 Grain Very Low Drag (VLD) Target
G7 BC: 0.262

30 Caliber 185 Grain Juggernaut Target
G7 BC: 0.284

30 Caliber 200.20x Hybrid Target
G7 BC: 0.328

30 Caliber 215 Grain Hybrid Target
G7 BC: 0.354

30 Caliber 230 Grain Hybrid Target
G7 BC: 0.368

30 Caliber 220 Grain Long Range Hybrid Target
G7 BC: 0.369

Here we see that in general, higher weight = higher BC but we also have an improvement in design that has caused the 220 grain to have the same BC as the 230. BUT, I would never run the 230 from a 308 Win because I wouldn't be able to push the bullet fast enough to utilize that extra BC to make it out perform the 200.20x, but from a 300 PRC I would be able to get it moving fast enough were it would overtake the 200.20x. So it isn't as simple as higher BC = best bullet for my cartridge. But in general, you want to go as heavy as you can while keeping the MV (muzzle velocity) fast enough to make use of the advertised BC.

I am not 100% confident in my understanding of this but IIRC, BC is not static, it is a factor of MV.

Anyway, this stuff can get really complicated so the easiest thing is to look at what other people are doing. If I had a 32" FTR rifle I would shoot the 200.20x's. If I had a 24" 11.25 twist 308, I would probably run 185's max. Which reminds me, you also need to make sure your rifles twist rate is sufficient for a particular bullet.

Those lighter bullets have a higher muzzle velocity but lower BC: ballistic coefficients (How well it cuts through air). So they will slow down at a faster rate then those heavy bullets. The biggest problem is going to be wind, drop can be calculated for easily but wind can not.

In general, heavier bullets have higher BC. There are exceptions like those fancy lathe turned solid copper bullets that are light and have a high BC. Shape also matters, a stubby bullet vs a sleeker one can weigh the same but have different BC's. But if we are talking the same type and shape, heavier = higher BC.

Let us look at some 30 cal Berger bullets:
30 Caliber 175 Grain Very Low Drag (VLD) Target
G7 BC: 0.262

30 Caliber 185 Grain Juggernaut Target
G7 BC: 0.284

30 Caliber 200.20x Hybrid Target
G7 BC: 0.328

30 Caliber 215 Grain Hybrid Target
G7 BC: 0.354

30 Caliber 230 Grain Hybrid Target
G7 BC: 0.368

30 Caliber 220 Grain Long Range Hybrid Target
G7 BC: 0.369

Here we see that in general, higher weight = higher BC but we also have an improvement in design that has caused the 220 grain to have the same BC as the 230. BUT, I would never run the 230 from a 308 Win because I wouldn't be able to push the bullet fast enough to utilize that extra BC to make it out perform the 200.20x, but from a 300 PRC I would be able to get it moving fast enough were it would overtake the 200.20x. So it isn't as simple as higher BC = best bullet for my cartridge. But in general, you want to go as heavy as you can while keeping the MV (muzzle velocity) fast enough to make use of the advertised BC.

I am not 100% confident in my understanding of this but IIRC, BC is not static, it is a factor of MV.

Anyway, this stuff can get really complicated so the easiest thing is to look at what other people are doing. If I had a 32" FTR rifle I would shoot the 200.20x's. If I had a 24" 11.25 twist 308, I would probably run 185's max. Which reminds me, you also need to make sure your rifles twist rate is sufficient for a particular bullet.

Thank you Raining !
I'm actually reading Bryan Litz book "Applied ballistics for LR shooting" and so far as I can tell, he's moving away from the G1 standard profile for long range shooting. Prefering the G7 profile for it is not velocity dependant and gives a much "Truer" trajectory profile. The older G1 profile varies greatly from the shape of pointier, boat tail bullets and he explained that G1 BC are very much velocity dependant

I appreciate the time you took to share uour knowledge and am having a good time with Bryan's book !!

 

[b6graham]

Thank you Raining !
I'm actually reading Bryan Litz book "Applied ballistics for LR shooting" and so far as I can tell, he's moving away from the G1 standard profile for long range shooting. Prefering the G7 profile for it is not velocity dependant and gives a much "Truer" trajectory profile. The older G1 profile varies greatly from the shape of pointier, boat tail bullets and he explained that G1 BC are very much velocity dependant

I appreciate the time you took to share uour knowledge and am having a good time with Bryan's book !!

They both work and give basically the same output

Data in more important

 

[MarinePMI]

They both work and give basically the same output

Data in more important

This ^^^^

 

[Rocketvapor]

Take something popular like the .308 200.2 grain.
Advertised G1 of .64 and a G7 of .328.
Run it @ 2700 or so out to 1000 yards.
Make wind calls to within 5mph of actual (easy peasy ? )
G1 gives 0.95 mils drift, G7 gives .92 mils (at sea level).

Maybe it's more useful at ranges longer than 1000.

 

[b6graham]

Take something popular like the .308 200.2 grain.
Advertised G1 of .64 and a G7 of .328.
Run it @ 2700 or so out to 1000 yards.
Make wind calls to within 5mph of actual (easy peasy ? )
G1 gives 0.95 mils drift, G7 gives .92 mils (at sea level).

Maybe it's more useful at ranges longer than 1000.

Depending on barrel bullets speed etc etc either if those could be close

Custom curves.
4dof and form factor.
Cold Bore.

It's just a spreadsheet and formulas

 

[Rocketvapor]

Exactly.
You need to know muzzle velocity and DA.
For the 2700 fps given, one shot @ 1000, a 10 mph full value left to right wind you called 15nph (5mph error)
Where would you hold for your first shot?
.92 or .95 mils, left or right of the center of a 1 MOA plate?

If you were GOOD at wind calls and called that 10MPH FV 12MPH,
How big a different in hold using published G1 or G7?

Dang, I did it again, this is a 1 mile thread. Sorry. I'll shut up.

 

[CygnusX1]

Take something popular like the .308 200.2 grain.
Advertised G1 of .64 and a G7 of .328.
Run it @ 2700 or so out to 1000 yards.
Make wind calls to within 5mph of actual (easy peasy ? )
G1 gives 0.95 mils drift, G7 gives .92 mils (at sea level).

Maybe it's more useful at ranges longer than 1000.

I whent back in Bryan Litz book on the BC chapter and at 1000 yards, we're talking a difference in bullet speed of about 75 fps between G1 and G7.....and a difference in bullet drop of 10 inches. Yes it's close.

But I can see that if I start off with a marginal caliber to hit 1000 yard target, then the small differences in G1 and G7 will cause a miss..... or my bullet being transonic at the target

This raises an interesting question:
For a 1000 yards shot, do you choose a caliber that stays supersonic 10 % past 1000 yards or 20 % or even greater ?

Thank you for your insights !

 

[_Raining]

For a 1000 yards shot, do you choose a caliber that stays supersonic 10 % past 1000 yards or 20 % or even greater ?

There are general trends for specific competitions:
F Class (Midrange 300-600) - 6 BR and BR variants will do well here.
F Class (Long Range 700/800/900/1000) - Based on what I have read, looks like the 284 Win/Shehane is popular but you also have 7 SAUM, 300 WSM, and things of that nature.

The idea seems to be that 6 BR variants are easy to tune and seem to produce the tightest groups but if you put wind in the mix it can be better to step up to the 7mm rounds. I am pretty sure the BR world record at 1K for smallest group was from a 6 BRA but that is 5 rounds vs the 20 you need for F Class so wind changing is a bigger problem since you shoot more rounds and thus more time passes giving the wind more time to fuck you in the ass.

F Class T/R (Limited to 308 and 223) is mostly dominated by 308 but some crazy mofos do well with 90 VLDs but I have read they can be finicky to reload for. F class Open and T/R use long barrels to squeeze out as much velocity as they can (28-32" it seems is around where most people are). Berger seems to be the most popular bullets used aside from the custom 6mm's for BR (For 308 it was 200.20x but I guess the new 208 will be the new hotness).

PRS Seems to be dominated by the 6mm's, with the idea being do you care about barrel life, if yes you are closer to 6 BR, if not you are closer to 6 creedmoor. So we got 6 BR, 6 BRA, 6 BRX, 6 Dasher, 6 GT, 6 XC, 6x47, 6 creedmoor (I am sure I am missing a few). But they all poretty much use Berger 105's or the 115 DTAC but it has been a bit since I did research on this so there might be a few other ones (I think there is a new DTAC? and Berger has the 108/109 also). I just use the 105's in my Dasher as I have 1k of them.

I am not into ELR but the KO2M What the pros use showed 416 Barret and 375 Cheytac as the common rounds.

Then you have the new 6.5 PRC which doesn't really fit into a competition category (too much recoil for PRS) but is good for hunting and general not competitive long range shooting to go past PRS distances. 300 PRC also same thing, not really competition used but is good for long range beyond PRS distances.

Faster bigger higher BC etc will give you an advantage against the wind but you need to factor in recoil and barrel life into what you want. If you are competing, just pick one of the popular rounds.

6.5 creedmoor is good for F Class and PRS but it isn't going to be the most popular for either but is a pretty good default for entry into precision rifle shooting. Tons of rifles and ammo availability in 6.5 creedmoor.

 

[Rocketvapor]

Drop can be dialed.
Wind must be read.

 

[b6graham]

Drop can be dialed.
Wind must be read.

there's a reason Berger shot 208s in FTR last week