"Inherent accuracy question(s)"

[critter]

I have seen several threads attempting to compare inherant accuracy of various rounds such as 9mm-40 S&W-.45 ACP-.357 sig, etc. It is also done with rifle rounds and it is generally 'accepted' that short, fat rounds are better at IA than long skinny ones. That is, 308 is better than 30-06, the short fat ppc type rounds are 'good' and that the new ultra short rounds are 'very good' in this area.

It seems to me that 'inherant accuracy' refers to the 'top accuracy potential' of a ROUND. That is, it is NOT related to the specific gun, how it is fired, by whom, etc. Since no two guns can ever be exactly identical except for caliber and that actually no two shooters can be equally accurate, etc. , then I have a question.

How in the world can it be determined that caliber X is more inherantly accurate than caliber Y?

I know that many say the the .45 is better than the 40 or 9mm. Well, there has been nearly century of 'tweaking' on the .45 and guns to shoot it and aftermarket enhancement methods and accessories. The same is true for the 40 and the 9 BUT NOT NEARLY TO THAT GREAT extent. Is THAT why many people believe the 45 is more 'inherantly accurate' than the others (even though NONE of these things ACTUALLY have anything to do with the ACCURACY POTENTIAL of the round)?

Sorry to be so long winded. Just wondering. OR----maybe I'm totally off base altogether. If so, straighten me out!

Thanks.

 

[BluesBear]

There are so many factors involved.

I think that the "Inherant Accuracy" claims started back in the black powder days. It seems that the .44 Russian cartridge (for example)had just the right combination of case capacity and bullet design (diameter vs length) and was used by target shooters for many years.

Actually I believe "Inherant Efficiency" would be a better term for today.

It would seem that the .38 Specail is more efficient (for target shooting) when loaded with a deep seated wadcutter. This allows for better combustion of the smaller charges. So the better accuary would be caused by increased efficiency.

The new fad of the super-duper-short rifle cartridges is based on the premise of having the powder charge closer to the primer. The case volume is little, if any, changed from older cartridges so any actual improvement would be due to better efficiency.

Bullet shape & weight. Powder charge vs capacity. Consistant combustion.
All of these would lead to better or worse accuracy.

 

[Standing Wolf]

Actually I believe "Inherant Efficiency" would be a better term for today.

I think you're probably right. I believe there are bullet designs and loads and barrels that are more conducive of accuracy than others, but accuracy may well be a form of efficiency rather than a thing unto itself. It's been a long time since I took a physics course!

 

[Matt G]

On more than one occasion, I read Gale McMillan state that the .222 was inherently more accurate than the .223. I didn't ever know why, knew enough to recognize that the man had the experience to have seen the difference.

There's a lot of dynamics, I know, involving surface area of the interior of the case, shape of the charge area, volume of the case, seating depth, etc. Many say that the case neck size is important. The .300 Win Mag is supposedly at a design disadvantage because of its short neck. The belt on the case head is another expected disadvantage for high accuracy; most say the way to go is to headspace on the shoulder.

Then there's the expected load. The old .244 got a bad rap for bad accuracy, because the rifle twists were cut for the lighter varminter bullets. When they cut faster twists for barrels with the same chamber so that heavier bullets could be used for deer-sized animals, the 6mm was born. Both were accurate, and used the same case. Just had to match the rifle to the bullet weight.