Luckily i’m Typing on a screen which will limit rambling... lets assume all else is same, ie action tolerances, brass, barrel etc... what is it that makes the 22br more accurate then the 22-250 or is it really? In general one assumes it’s some unknown exactly internal ballistics that the cartridge performs better because of its design. I ask because the 270wsm appears to have a case that looks more like the most “accurate” cartridges then the 270win but I haven’t read a single thing online from anyone analyzing the differences in accuracy. This is just a random question that crossed my mind.
Cartridge accuracy....
- Thread starter 270WinDude
- Start date
Dusty Stevens
Shiner
Has anybody ever analyzed the accuracy potential of any 270 cartridge? Killing yes- accuracy no. Powder column compared to bullet dia is what makes the difference. The formula? I have no idea but i do know what designs have what characteristics and can usually tell if theyre going to shoot well just by looking at it compared to known well shooting designs
I have build 1/4moa 270WSM's......the limiting factor is bullets.
Barnes 130-140 'ish TTSX's and Nosler Ballistic Tips will shoot quarter minute. I don't know if they'll shoot better than that.
It's a decent round, just limited in the availability of true Match Bullets IMO.
That said, since I've learned how to make LA Rem700's shoot as well as SA Rem700's, the 270 Win is also a 1/4moa round.
I bought Nosler lrab, 130sst, Berger 130 140vld, Sierra 135 match, 110 vmax, 90 Varminters, and if I can’t get what I want from some of those will try ce bullets or matrix. I’m mostly curious about cartridge design on accuracy specifically this one. Yours all seem to shoot nice, I’m assuming handloads
Grimstod
Machinist, Designer, and Shooter.
What makes one case more accurate(wider tune window) then another has to do with its width to length ration and bore dimension. Basically moving these three factors around makes the accuracy node wider or narrower. Two cartridges with wide or narrow load nodes can produce the same accuracy but as conditions change, ie temp etc, then the one with the wider load node will group better. In the end it all boils down to which of the two is the most forgiving of mistakes that are inevitably going to happen with all the other aspects of what makes accuracy happen.
Alex Wheeler
Site $$ Sponsor
I have read about the short fat cases being more accurate. But its not like we have a lot of control over the fat part of the equation. If that was the whole story why are we not seeing shortened 6br cases instead of ppcs? You could make a shorter fatter case of equal capacity stating with br brass and I know they played with the br case a lot.
Alexander-M
Gold $$ Contributor
Would it be correct to say that if we were to consider the cartridges we shoot, from .22 to .35 caliber, and providing that for each we would use the best combination of brass, primer, powder charge, bullet, barrel length, twist, etc., that some are inherently more accurate than others at specific distances? Just as examples: the 6PPC at 100 yards, and 6mm Dasher at 600 yards? (Please note that I really do not know if these examples are correct.)
Alex
Alex
dmoran
Donovan Moran
Cartridge efficiency is what can make one cartridge more accurate then another.
When a smaller capacity cartridge, can produce near equal velocities for a given bullet weight, it is more efficient, hence; more inherent accuracy.
Cartridge Efficiency:
(Bullet Weight * .5) * (MV ^ 2) / (Charge * Joules per grain) / 98000 = % of efficiency
Note:: (kJ/kg / 15.4324 = Joules per grain)
Examples:
6Dasher:: 105-VLD <> 3000-fps <> 32.5 of RL-15 = 57.4%
243-Win:: 105-VLD <> 3000-fps <> 44.5 of H4350 = 44.9%
When a smaller capacity cartridge, can produce near equal velocities for a given bullet weight, it is more efficient, hence; more inherent accuracy.
Cartridge Efficiency:
(Bullet Weight * .5) * (MV ^ 2) / (Charge * Joules per grain) / 98000 = % of efficiency
Note:: (kJ/kg / 15.4324 = Joules per grain)
Examples:
6Dasher:: 105-VLD <> 3000-fps <> 32.5 of RL-15 = 57.4%
243-Win:: 105-VLD <> 3000-fps <> 44.5 of H4350 = 44.9%
Last edited:
Alex Wheeler
Site $$ Sponsor
This is probably the best answer. Accuracy and efficiency are certainly tied together.
Assuming accuracy really means precision here:
A 6PPC is not accurate due case design, but due to it's combinations and vast use. One benefiting another and then another, etc. Similar to racing engines.
It always starts with a bullet, but considering the case itself first, it's tiny for bore (way underbore).
That small area, including small diameter to get more barrel steel around the chamber, still without detrimental powder column length, allows for extreme pressure loads with a good filling of very fast and very cool burning N133. This, even at competitive pressures, in very short/stiff barrels, burns so completely as to produce very little muzzle pressures. Add FB bullets(bullet beginning), and you get super clean bullet release. If these bullets are light/short, you get to run very low twist for less torqueing, and less recoil affecting the shooting system. Add a very limited use, short range BR only, and it takes some effort to beat it, so many shooters embrace the simplicity in this path, and everything good or bad in it is quickly known to all. Benefiting all.
A factor in this use is cycle speed for condition shooting, so the case has moderate angles for easy feeding and extraction.
It,s said to be a 'design', but mere evolution would lead to it in any of similar forms. A 30BR in comparative system design comes to mind. The same would eventually happen at other ranges/uses.
A 6.5x47L/130s is close for mid ranges. 260AI/140s for 1kyd. Successful cartridges that are not underbores, but perfect capacities for bore(bullet beginning). These could be tweaked any slightest amount and assume historical significance similar to 6PPC. We'll see.
After 26cal, for long range, far more factors with diminished returns remove settled combinations and vast use. We'll likely never see something settled on at 1kyd(like a 6PPC at 100yd).
'Best hunting cartridges' per cal, is way more complicated than precision on paper under preconditions..
IMO, there are so few hunters that actually reach for best, that credible standards will never develop to a following. For some reason hunters go to odd cals, and for some reason odd cals are usually lacking in best bullet selections. None of that helps.. So why does 27cal even exist, while the best bullets are offered in 28 & 30 cals?
Never forget: it always starts with a bullet.
Even for hunting, best bullets lead to best accuracy, which is the most powerful of ballistic attributes.
A 6PPC is not accurate due case design, but due to it's combinations and vast use. One benefiting another and then another, etc. Similar to racing engines.
It always starts with a bullet, but considering the case itself first, it's tiny for bore (way underbore).
That small area, including small diameter to get more barrel steel around the chamber, still without detrimental powder column length, allows for extreme pressure loads with a good filling of very fast and very cool burning N133. This, even at competitive pressures, in very short/stiff barrels, burns so completely as to produce very little muzzle pressures. Add FB bullets(bullet beginning), and you get super clean bullet release. If these bullets are light/short, you get to run very low twist for less torqueing, and less recoil affecting the shooting system. Add a very limited use, short range BR only, and it takes some effort to beat it, so many shooters embrace the simplicity in this path, and everything good or bad in it is quickly known to all. Benefiting all.
A factor in this use is cycle speed for condition shooting, so the case has moderate angles for easy feeding and extraction.
It,s said to be a 'design', but mere evolution would lead to it in any of similar forms. A 30BR in comparative system design comes to mind. The same would eventually happen at other ranges/uses.
A 6.5x47L/130s is close for mid ranges. 260AI/140s for 1kyd. Successful cartridges that are not underbores, but perfect capacities for bore(bullet beginning). These could be tweaked any slightest amount and assume historical significance similar to 6PPC. We'll see.
After 26cal, for long range, far more factors with diminished returns remove settled combinations and vast use. We'll likely never see something settled on at 1kyd(like a 6PPC at 100yd).
'Best hunting cartridges' per cal, is way more complicated than precision on paper under preconditions..
IMO, there are so few hunters that actually reach for best, that credible standards will never develop to a following. For some reason hunters go to odd cals, and for some reason odd cals are usually lacking in best bullet selections. None of that helps.. So why does 27cal even exist, while the best bullets are offered in 28 & 30 cals?
Never forget: it always starts with a bullet.
Even for hunting, best bullets lead to best accuracy, which is the most powerful of ballistic attributes.
270WinDude
When ya find a 270 more accurate than this.....let me know!
15shot by Sharps Man, on Flickr
When ya find a 270 more accurate than this.....let me know!
15shot by Sharps Man, on Flickrnice picture, is that a typical 6" mil bullseye?
(pics with no reference are just pic's,
what distance, and how big is the target)
(pics with no reference are just pic's,
what distance, and how big is the target)
270WinDude
When ya find a 270 more accurate than this.....let me know!
CaptainMal
Silver $$ Contributor
The 270 WSM just may be super accurate by design. Yet, the size of the case and the amount of powder used, takes it out of the normal helm of a cartridge that would be used for super accurate shooting. As a result, few shooters have probably worked hard, barrel after barrel and test after test to find out in a target format. Ancillary to that would be slight primer, case, powder and bullet tweaks not being done with that case. Then you would have to deal with the issue of few to maybe NO bullet manufacturer by custom individual bullet makers in styles and designs for target usage. It is rare to see any production bullets from companies like Berger, Sierra, Hornady etc. come close in quality to what Barts, Vapor Trail, and all the short-range bullet makers produce.
The short version of all this is there's little reason to mess with this cartridge for serious target use with so many others available that do work.
The short version of all this is there's little reason to mess with this cartridge for serious target use with so many others available that do work.
Matrix Ballistics make a range of match bullets for the 277 caliber from a 147 to 175 grain. This is because the previous owner loved the caliber and simply wanted to use the caliber in F-Class competition just to be different. He started with 270 WSM and worked his way down through the various cases. The most accurate case is a 270-308 AI so far.
Having shot against him in the past I can definitely say the 270 caliber will shot well.
Having shot against him in the past I can definitely say the 270 caliber will shot well.
Actually, there was some experimentation some years ago by Fred Hasecuster and a few others. The 6 BR case was shortened by various lengths. The one I had/have is .100 short, making it much closer to the capacity of a PPC. It shoots on a par with a 6 PPC, but is a PIA to make. Since you already have the PPC, there isn't much point, but it did/does work.
Rick
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