Ballistics question

I admit, I am lazy when it comes to too much research.
My question for the ballistics gurus here is this....How can a hollow point projectile be more accurate than a round nose projectile given all other components and variables equal?
Ron

I alluded to the answer when I discussed the 185gr SWCHP. Two bullets both weighing the same but one has it's weight on the outside and the other shorter and with its weight centralized. The HP has a greater contact surface with the barrel creating less blow by and also has its weight on the outside for better stability. Were not talking much difference here but it is noticeable.

Len

In addition, a hollow point creates turbulence in front of the hole, which is an area of high pressure vs the lower pressure around the sides of the bullet. That contributes to the bullet staying "straight"...

Dave

Multiracer wrote:I admit, I am lazy when it comes to too much research.
My question for the ballistics gurus here is this....How can a hollow point projectile be more accurate than a round nose projectile given all other components and variables equal?
Ron

For jacketed bullets it’s easier to make a high quality jacket cup for a hollow point rather than a FMJ whether RN ot SWC. The bullet bases also are square to the bullet shank which is key,

For lead, a HP is actually destabilizing but the effect is minimal at pistol velocities and ranges. However, the HP allows a longer bearing surface for the same weight and nose profile. The Magnus 185 SWCHP is the same basic profile as the 200SWC swaged bullet and both have a nice long bearing diameter. It just cuts the weight to reduce recoil.

Other items seem to contribute to the better overall performance of JHP projectiles.  

The metal jacket is formed and the lead core is inserted  base first, creating a complete covering of the bullet base (which leaves the opening of jacket at the front versus FMJ projectiles which generally, but not always" have open bases).  This forming process produces a very consistent base.

Secondly, and in my personal opinion a very important part, is the formation of the bullet profile and then "hollow point" creation are generally in two steps for a JHP projectile.  In effect, when this process is used  the bullet is formed or swaged a second time during the creation of the "hollow point" and nose configuration.  This appears to provide some additional consistency in the sizing and overall configuration (measurements) of the bullet from the base forward.  But not necessarily the overall length since there is some variation around the nose with some jacket / hollow point opening configurations.  (Measure the OAL of the projectiles and see what variance you get. Then look at the very nose end of the bullets.) 

In an overall opinion, you might say in general the variances in a JHP are toward the nose and the variances for JHP are toward the base. 

(And its also why you will find that using overall length / seating using the flat nose only will produce some variation in some JHP loads.  So, make sure your bullet seater is modified to contact the bullet at some place on the ogive of the bullet and not just the nose only for better seating consistency with respect to the bullet / throat distance.) 

CR