Range Report Bullet Surface Area, Velocity and Barrel Heating

[Valere]

Sorry if I posted this in the wrong section. Please redirect if I did.

This is mainly a question out of curiosity rather than practicality. I'm not sure how or if this would effect group size but would still like to know the info.

Is there any relationship between the amount of bullet surface area in contact with the barrel and barrel heating? I don't have the ability to measure this, nor its significance if any, but it would seem that two bullets traveling at the same speed will create more or less heat based on the surface are in contact with the barrel. Considering that, what is the relationship between velocity and heat and surface area and heat, which one creates more.

I'm no mathematician, so please excuse the poor example.

If I have two bullets that travel at 3000fps, one contacts .5" of rifling and the other .6". Presumably the .6" will create more heat. Take the .5" bullet vary it's velocity in 100fps increments. Presumably the faster velocity will create more heat. Between the two variables of heat production, which creates more respectively a .1" increase or a 100fps (or any other predetermined value) increase?

Just curious to see the trade off in heat when people switch to super long bullets at lower velocities or ultra fast smaller bullets. I realize this may be completely insignificant in the grand scheme of things.

 

[The Mechanic]

Re: Bullet Surface Area, Velocity and Barrel Heating

In short, no.
The GREAT majority of the heat is from powder burning. The contact of the bullet is for such a small amount of time it is insignificant compared to the explosion of hot gasses just behind it.

 

[K2Ballistics]

Re: Bullet Surface Area, Velocity and Barrel Heating

Combustion trumps friction!

 

[coldboremiracle]

Re: Bullet Surface Area, Velocity and Barrel Heating

Ive often wondered a similar question, if I have two bullets of Identical weight but one has 50% less bearing surface, will it go faster or slower, and will one burn up the bore sooner than the other?

 

[The Mechanic]

Re: Bullet Surface Area, Velocity and Barrel Heating

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: coldboremiracle</div><div class="ubbcode-body">Ive often wondered a similar question, if I have two bullets of Identical weight but one has 50% less bearing surface, will it go faster or slower, and will one burn up the bore sooner than the other?</div></div>
It would be more important how each one of those bullets sealed against the bore rather than just a matter of surface area. Same reason poly bores seal better but technically would have larger surface area but yet has longer barrel life.

 

[K2Ballistics]

Re: Bullet Surface Area, Velocity and Barrel Heating

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: coldboremiracle</div><div class="ubbcode-body">Ive often wondered a similar question, if I have two bullets of Identical weight but one has 50% less bearing surface, will it go faster or slower, and will one burn up the bore sooner than the other? </div></div>

All other things being identical, the one with more surface area would travel slower due to increased friction losses.

Barrel life is almost solely determined by throat erosion resulting from the combustion process. Cartridge design, pressure levels, powder characteristics, bore temperature and barrel metallurgy are the primary determinants.

Jeff