The Inherently Accurate Cartridge!
The Inherently Accurate Cartridge!
what
Last edited by a.JR on Sun Mar 16, 2008 10:40 am, edited 1 time in total.
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woob614271
- 17Rem
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Ned Kelly
- .270 Winchester
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G'Day a.JR,
I'd have thought that both accuracy and efficiency went hand in hand........
The little i know about thermodynamics makes me think they must work together. Efficient combustion must aid the harmonics, and the design of a case has to have some effect on combustion process, gas flow and all the thermodynamic stuff to ensure here are no choke points to inhibit the gas flow into the barrel, but also provide optimum conditions for a consistent burn to ensure all the fuel is burnt everytime for good consistent barrel pressures, MV, SD and ES etc.
Just my thoughts anyway......
Cheerio Ned
I'd have thought that both accuracy and efficiency went hand in hand........
The little i know about thermodynamics makes me think they must work together. Efficient combustion must aid the harmonics, and the design of a case has to have some effect on combustion process, gas flow and all the thermodynamic stuff to ensure here are no choke points to inhibit the gas flow into the barrel, but also provide optimum conditions for a consistent burn to ensure all the fuel is burnt everytime for good consistent barrel pressures, MV, SD and ES etc.
Just my thoughts anyway......
Cheerio Ned
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Ned Kelly
- .270 Winchester
- Posts: 1277
- Joined: Tue Oct 31, 2006 6:39 am
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- Location: Macedon Ranges Vic
G'Day a.JR,
If your hoping to bait people, keep trying mate!
I was simply trying to see things from your perspective. I own a chronograph but have never chrony'd my ppc and have only used it to check my .223 to develope some LR drop charts for FO.
IMHO, if the load shoots flat groups the gun is tuned. I have little experience at LR such as yourself and the question is too open to have a definitive answer. At LR I'm begining to think if 70% of shots group well it is either conditions or technique that is at fault.
Out to say 600, the smaller cases such as the ppc and BR family I have witnessed superb accuracy or around 0.3moa or less. Which it seems is right when you say they reach their limits. the possibles on the ozfclass site shows the possibles at the longs are not the 6BR's that rule.
Beyond that, horsepower has a definate advantage, why else do the 1000yd BR/FO shooters reach for 300WM or 284 or similar for the longs.
Ultimately the smart shooter follows what is happening in the competitive field that interests them or is applicable to their style of hunting and then use what is successful because the R&D has been done and PROVEN in competition........where it counts!
I prefer empirical data everytime and look seriously at good theories based on that data. I think its called science and reasoning! And given I come from an aviation engineering background I'd expect a little credit for having some technical knowledge.......and not being dogmatic otherwise I'd be denying the existence of the very industry I work in!
So any well made and prepared case can be made to shoot exceptional well and to say a long and thin case cannot do so, simply ignores the history of BR with the record setting and breaking .222, the long range success of the .223 and any of your favourite LR BR cases............
Cheerio Ned
If your hoping to bait people, keep trying mate!
I was simply trying to see things from your perspective. I own a chronograph but have never chrony'd my ppc and have only used it to check my .223 to develope some LR drop charts for FO.
IMHO, if the load shoots flat groups the gun is tuned. I have little experience at LR such as yourself and the question is too open to have a definitive answer. At LR I'm begining to think if 70% of shots group well it is either conditions or technique that is at fault.
Out to say 600, the smaller cases such as the ppc and BR family I have witnessed superb accuracy or around 0.3moa or less. Which it seems is right when you say they reach their limits. the possibles on the ozfclass site shows the possibles at the longs are not the 6BR's that rule.
Beyond that, horsepower has a definate advantage, why else do the 1000yd BR/FO shooters reach for 300WM or 284 or similar for the longs.
Ultimately the smart shooter follows what is happening in the competitive field that interests them or is applicable to their style of hunting and then use what is successful because the R&D has been done and PROVEN in competition........where it counts!
I prefer empirical data everytime and look seriously at good theories based on that data. I think its called science and reasoning! And given I come from an aviation engineering background I'd expect a little credit for having some technical knowledge.......and not being dogmatic otherwise I'd be denying the existence of the very industry I work in!
So any well made and prepared case can be made to shoot exceptional well and to say a long and thin case cannot do so, simply ignores the history of BR with the record setting and breaking .222, the long range success of the .223 and any of your favourite LR BR cases............
Cheerio Ned
Ned, it's interesting that you mention the 222. I hate this bit where i have to remind all the PPC pundits that the old 222 still holds the world record small group at 100 yds in a registered BR match. PJ Hart did it in the 70s at about the time the 22 and 6 PPCs were winning everything and the 6PPC was considered the accuracy king even at this early stage. So even then this group was doubted by many as being a fluke or even illegal as everyone expected that a PPC would take this crown. After more than 30 years that 0.009 inch group has been measured and talked about many times to gauge its authenticity.
Now the history of the 222 is from BR royalty with Mike Walker developing the little case in 1950. It is an original case in that it has no parent. It has been claimed that Walker developed it from a two thirds version of the 30/06 and if one does a scale drawing it is pretty close barring the extra long neck by proportion. So we have a case that is long and thin, and oh no, it has a 82 thou flash hole with a small rifle primer. So how does this case still hold the small five shot group record at 100 yards still to date? Easy, barrel, bullets, a powder that suits the case volume and then it just comes down to pressure and time. That's it. The shoulder angle is wrong at 23 degrees, the case length to diameter ratio is wrong, the flash hole is way too big. So everything is wrong and it still holds that record and Sierra used that case for all 224 projectile accuracy testing for years after and may still do so.
One of the annoying things about case design and its benefit to accuracy is the corrolation even the most experienced shooters place on gas flow like it is a port in an engine or a pump. This is so far from the real world on one very major difference. A pump or engine evacuates the chamber and leads the gases into the exhaust, by an ever decreasing volume. A rifle case has an ever expanding combustion chamber where the gases follow the gas laws with a peak, average, a low and a negative presure throughout the course of a firing cycle. The peak is obviously the full cumbustion working pressure, the average is the pressure required to drive the projectile to a certain velocity, the low is the pressure at the muzzle right at the time of projectile exit, and the negative is the gas flow momentum evacuating the chamber and bore creating a slight vacuum. This vacuum is by nature just a simple example of basic fluid dynamics.
In no way can case design be construed to be factored around flow characteristics, but more about pure mechanical advantage and strength. Brass is not very strong by nature and its crystalline structure makes it suseptable to fracturing from work hardening or just plain vibration or even precipitation hardening over many years laying dormant.
If it was possible, and some have tried, a spherical case would be the most user beneficial to create the most consistant pressure curve to send a projectial down range. But to date this design is not viable to the greater world, and even if it was, i doubt that it would change much.
The great accuracy benefits we have seen in recent years have more to do about suitable powders, great bullets and their jackets, barrels that are uniform to a couple of hundred thousanths of an inch and rifle ergonomics.
As far as accuracy goes we are small players. When i was working in Army Intelligence as part of my sniper training in the eighties, we often had the latest info on weapons etc at our disposal. The Isrealis in the early 80s had a 155mm liquid propellant mobile field artillery piece that had radar directional aim control that could pick up a bunkered enemy tank or artillery piece firing and within seven seconds would calculate, aim and launch a HE shell and "remove" the offender to a range of over 20 ks. Now this was a free flight projectile not a wire or optically guided rocket. So if you sat in your little enemy tank and were dumb enough to fire and give off the signature the radar was looking for, you had seven seconds plus time of flight to move or you were removed. Think about that in MOA terms and you will quickly see that we are playing with our dicks if we think we have this accuracy thing by the balls. To date, that i know of, that artillery piece and used technology has been witheld from all including the yanks.
Tony Z.
Now the history of the 222 is from BR royalty with Mike Walker developing the little case in 1950. It is an original case in that it has no parent. It has been claimed that Walker developed it from a two thirds version of the 30/06 and if one does a scale drawing it is pretty close barring the extra long neck by proportion. So we have a case that is long and thin, and oh no, it has a 82 thou flash hole with a small rifle primer. So how does this case still hold the small five shot group record at 100 yards still to date? Easy, barrel, bullets, a powder that suits the case volume and then it just comes down to pressure and time. That's it. The shoulder angle is wrong at 23 degrees, the case length to diameter ratio is wrong, the flash hole is way too big. So everything is wrong and it still holds that record and Sierra used that case for all 224 projectile accuracy testing for years after and may still do so.
One of the annoying things about case design and its benefit to accuracy is the corrolation even the most experienced shooters place on gas flow like it is a port in an engine or a pump. This is so far from the real world on one very major difference. A pump or engine evacuates the chamber and leads the gases into the exhaust, by an ever decreasing volume. A rifle case has an ever expanding combustion chamber where the gases follow the gas laws with a peak, average, a low and a negative presure throughout the course of a firing cycle. The peak is obviously the full cumbustion working pressure, the average is the pressure required to drive the projectile to a certain velocity, the low is the pressure at the muzzle right at the time of projectile exit, and the negative is the gas flow momentum evacuating the chamber and bore creating a slight vacuum. This vacuum is by nature just a simple example of basic fluid dynamics.
In no way can case design be construed to be factored around flow characteristics, but more about pure mechanical advantage and strength. Brass is not very strong by nature and its crystalline structure makes it suseptable to fracturing from work hardening or just plain vibration or even precipitation hardening over many years laying dormant.
If it was possible, and some have tried, a spherical case would be the most user beneficial to create the most consistant pressure curve to send a projectial down range. But to date this design is not viable to the greater world, and even if it was, i doubt that it would change much.
The great accuracy benefits we have seen in recent years have more to do about suitable powders, great bullets and their jackets, barrels that are uniform to a couple of hundred thousanths of an inch and rifle ergonomics.
As far as accuracy goes we are small players. When i was working in Army Intelligence as part of my sniper training in the eighties, we often had the latest info on weapons etc at our disposal. The Isrealis in the early 80s had a 155mm liquid propellant mobile field artillery piece that had radar directional aim control that could pick up a bunkered enemy tank or artillery piece firing and within seven seconds would calculate, aim and launch a HE shell and "remove" the offender to a range of over 20 ks. Now this was a free flight projectile not a wire or optically guided rocket. So if you sat in your little enemy tank and were dumb enough to fire and give off the signature the radar was looking for, you had seven seconds plus time of flight to move or you were removed. Think about that in MOA terms and you will quickly see that we are playing with our dicks if we think we have this accuracy thing by the balls. To date, that i know of, that artillery piece and used technology has been witheld from all including the yanks.
Tony Z.
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Ned Kelly
- .270 Winchester
- Posts: 1277
- Joined: Tue Oct 31, 2006 6:39 am
- Favourite Cartridge: 6PPC
- Location: Macedon Ranges Vic
G'Day a.JR,
where exactly in the original post did you specify LR BR only?
Unless you make a specific statement and put in the qualifying points such as "LR BR only" you WILL get background noise, so you had better craft the question properly or stop complaining when you get a reply from SR BR/F class shooters!
Otherwise your "credibility" will suffer from your sarcastic replies, lets face it, your second reply still did not qualify LR BR only shooters need reply!
Where have I ever said F class is LR BR shot prone? That's a ridiculous and frankly stupid statement to make. I've never said that, I made a "general" comment on the type of calibres that are used at 1000yds compared to the shorter ranges.
So stop reading things into my comments and then instilling your prejudices against SR BR and F class into your replies.......very bad form
So much for having an informed discussion on inherently accurate case design..............
Ned
where exactly in the original post did you specify LR BR only?
Unless you make a specific statement and put in the qualifying points such as "LR BR only" you WILL get background noise, so you had better craft the question properly or stop complaining when you get a reply from SR BR/F class shooters!
Otherwise your "credibility" will suffer from your sarcastic replies, lets face it, your second reply still did not qualify LR BR only shooters need reply!
Where have I ever said F class is LR BR shot prone? That's a ridiculous and frankly stupid statement to make. I've never said that, I made a "general" comment on the type of calibres that are used at 1000yds compared to the shorter ranges.
So stop reading things into my comments and then instilling your prejudices against SR BR and F class into your replies.......very bad form
So much for having an informed discussion on inherently accurate case design..............
Ned
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Ackley Improved
- 6mm Dasher
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- Location: Albury
AJR.. how come nearly all of your threads end up with a challenge, saying.... come compete against me.... we'll see who's smiling.... WTF man! I think if I read your posts, I will not read the last line of any of them now, as this is where it usually lies!
As for inherently accurate, I think any case can be made to shoot very well. Using all benchrest techniques, top components, near all calibers I feel would be respectful on a target, given the range. i.e a 30-30 can be made to shoot well at say 50m, but it apparently would not shoot well in real world conditions at 500m due to the restraints of the cartridge.
I also believe in efficient cartridges. Where the case shape, powder used in combination with projectiles results in higher velocity per powder weight to a similar cartridge. Case shape, due to the case being able to withstand higher pressure, results in these velocity increases. i.e PPC, BR, WSM's.
So, it appears to me, that it is a combination of factors, like powder, projectiles, primers, brass, brass prep, result in these inherently accurate cartridges....
Tony Z, from what I have heard, you are a better shooter than AJR stirring shit!
Cheers
AI
As for inherently accurate, I think any case can be made to shoot very well. Using all benchrest techniques, top components, near all calibers I feel would be respectful on a target, given the range. i.e a 30-30 can be made to shoot well at say 50m, but it apparently would not shoot well in real world conditions at 500m due to the restraints of the cartridge.
I also believe in efficient cartridges. Where the case shape, powder used in combination with projectiles results in higher velocity per powder weight to a similar cartridge. Case shape, due to the case being able to withstand higher pressure, results in these velocity increases. i.e PPC, BR, WSM's.
So, it appears to me, that it is a combination of factors, like powder, projectiles, primers, brass, brass prep, result in these inherently accurate cartridges....
Tony Z, from what I have heard, you are a better shooter than AJR
stirring shit! Cheers
AI
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Ackley Improved
- 6mm Dasher
- Posts: 1898
- Joined: Wed Aug 09, 2006 12:24 pm
- Location: Albury