Case design as accuracy factor

[marchx]

I am not a ballistician, so frankly speaking I am unable to verify the validity of accuracy discussions pertaining to different case designs.
Does short fat powder column as in case of BR make a round inherently more accurate than e.g. .284 win?
I heard that 300wsm reproduces to some extent 6BR case design which make it more accurate than other magnums.
It's all internet talk. Is there any merit in it?

 

[jackieschmidt]

Arguably the most accurate chamberings in the extreme accuracy game is the 6MM PPC, the 22 PPC .100 Short, and the 30 BR. All are classified as short and fat.

But that is in the 100/200/300 yard game.

In longer ranges, the fore mentioned 300 WSM is right at the top in pure accuracy potential. But so is the Creedmore line of cartridges which are not as “short and fat”

In the end, the given accuracy potential might have as much to do with the powder column volume as compared to the bullet diameter as anything.

But keep in mind. Accuracy, or Precision, can be relative to the Discipline you are shooting. True, the small cases I mentioned have the potential literally stack one bullet atop the other at shorter ranges where other factors of ballistic performance do not matter. Go out further and you need more powder column to push higher BC bullets at the ranges they are designed to shoot.

Logic dictates that you can only take “short and fat” to a certain extreme. Things such as bolt thrust at a given pressure come in to play, as well as the amount of metal left on the barrel tenon after chambering. If it did not, we would be seeing the WSSSSM line of chamberings.

 

[DaveTooley]

Case capacity comes into play. The 300 WSM is just about perfect for 30 caliber.

 

[dave@aDave]

Short, fat, sharp shoulder angle, and neck at least one (1) caliber long.
Pretty much describes 6PPC.

 

[Bc'z]

Short, fat, sharp shoulder angle, and neck at least one (1) caliber long.
Pretty much describes 6PPC.

And me...

I believe case efficiency has a lot to do with it, seems like efficient cartridges are accurate cartridges.

 

[jpjulian]

The short, fat design can be taken too far. The .223 WSSM I've been playing with again is a prime example as Jackie noted above. Temperamental little bastard it is....... and a BR or PPC it isn't....

 

[Dave M.]

I am not a ballistician, so frankly speaking I am unable to verify the validity of accuracy discussions pertaining to different case designs.
Does short fat powder column as in case of BR make a round inherently more accurate than e.g. .284 win?
I heard that 300wsm reproduces to some extent 6BR case design which make it more accurate than other magnums.
It's all internet talk. Is there any merit in it?

.284 win is a fantastically accurate round and still winning many 1000 yard F class matches today.

 

[Orr89rocz]

.284 win is a fantastically accurate round and still winning many 1000 yard F class matches today.

So surprising it hasnt stayed relevant in hunting rifles

 

[mattri]

So surprising it hasnt stayed relevant in hunting rifles

Kind of.
Most hunters aren't really really "shooters" the way we think of the term. They follow trends in the latest and greatest looking to buy accuracy/performance. Bowhunters may be even worse. Just how it is.
Get Hornady to rename it something snazzy and maybe it will get rediscovered.

 

[Old Navy]

My two most accurate cartridges every time to the range are my 6 BRA and my .284 Match.

 

[LCazador]

No doubt that the 6PPC with it's 30 degree shoulder and 1 1/2 degree leade angle set the pace for many cartridges but let us not forget the success of the 222. I think the shoulder angle, the neck length and the leade angle are the keys to an accurate cartridge.

 

[jackieschmidt]

.284 win is a fantastically accurate round and still winning many 1000 yard F class matches today.

Just rebrand it “the 284 Creedmoore” and it would fly off the shelves.

 

[Evan]

I would conjecture that case shape isn’t as important as hitting that magical point where your case capacity, bullet size and bearing surface, and powder pressure curve (not just peak pressure) all come together in unison. One example is the 6 BRA with H4895 - it works better than Varget/n140 class powders. Or to take the older path, 222 and IMR 4198. The ratio between all components was right.

 

[Phys86]

The majority of the reason the 284 win isn't popular within the hunting sector is because the factory ammo is nearly non-existent, and the stuff that does exist is not designed to reach it's full potential from a bolt gun, the 6.5-284 norma was designed with a stupidly short throat considering it's potential, and the brass for both is incredibly limited in comparison to other cartridges and often when it of stock.

It's not the cartridge itself that the hunting crowd follows .... It's the industry support for it.

Why is the creedmoor case and prc line so popular? Modern designs and incredible industry support because of Hornady ramming these things down every manufacturers throat.

We've lost out on incredible cartridges because of the lack of support and poor saami specs in comparison to what people want today. 7saum. 300saum. 300wsm (not as much support as it should have). 300rcm.

 

[Sandstorm]

It's not the cartridge itself that the hunting crowd follows .... It's the industry support for it.

Yup....as well as the late'st and greate'st...as long as its available and on the shelf.

 

[Old Navy]

Just rebrand it “the 284 Creedmoore” and it would fly off the shelves.

Reminds me of the .244 Rem that came out the same time as the .243 Win. By the time Rem rebranded it to 6 MM it was too late.

 

[marchx]

Why makes then 6br or 6ppc so stupidly accurate? How much does case design contribute to this?

 

[NZ_Fclass]

Case design? There's no straight forward answer, but...some cases ie, 6BR, .222 , 6PPC and the 7mm SAUM are easier to tune - is that the factor? Do they "seem" more accurate as more people shoot accurately with them?

On the contrary - are there case designs that are "inaccurate?

Is the 308 an "accurate" cartridge? Certainly with heavier projectiles, extensive tuning and skill, FTR shooters achieve scores close to F-Open competitors.

 

[Orr89rocz]

The majority of the reason the 284 win isn't popular within the hunting sector is because the factory ammo is nearly non-existent, and the stuff that does exist is not designed to reach it's full potential from a bolt gun, the 6.5-284 norma was designed with a stupidly short throat considering it's potential, and the brass for both is incredibly limited in comparison to other cartridges and often when it of stock.

It's not the cartridge itself that the hunting crowd follows .... It's the industry support for it.

Why is the creedmoor case and prc line so popular? Modern designs and incredible industry support because of Hornady ramming these things down every manufacturers throat.

We've lost out on incredible cartridges because of the lack of support and poor saami specs in comparison to what people want today. 7saum. 300saum. 300wsm (not as much support as it should have). 300rcm.

Isnt it kind of a Chicken or the egg thing? It was out there once, did ppl not buy it up? Did the guns that were chambered in it not shoot good?
If ppl bought them up, and there was demand for it, industry would have supported it i would have thought. If demand was not there, they slow production numbers in rifles and with that ammo declines…then it dies.

 

[Homerange]

Reminds me of the .244 Rem that came out the same time as the .243 Win. By the time Rem rebranded it to 6 MM it was too late.

While the ammo was the same the twist rate was increased in 6mm Rem to make good use of the heavier projectiles that quickly were desired.
These days many cals are available in different twist rates, back then it was not the norm and wisely the 6mm Rem moniker was used to differentiate between the 2 twist rates.