Bullet velocity and shape to mitigate a worn barrel

[davidjoe]

Given that after about one full match day of shooting, (that, after a break in, if it was useful or needed) barrels slowly but continually degrade in surface finish and dimensional uniformity, could the inevitable opening up of groups be mitigated by changes such as:

1) shooting the same bullets either faster or slower (which one exacerbates imperfections);

2) using a longer bodied bullet for a better gas seal;

3) using a slower burning powder, but more of it, to shift peak pressure and acceleration away from the more worn area near the throat;

4) switching to heavier or lighter bullets than one’s first choice (which one exacerbates imperfections)?

One could seek larger group mitigation through various ways of retuning the gun or seated load, but I’m wondering if there are theories supporting a change in components (choice in the type or amount of hardware, beyond tuning).

One observation that prompted the thinking in this direction is that one bullet in particular, the 180 Scenar seems more forgiving of barrel wear than others.

(Tangentially, I recall learning that the largest naval rounds were each produced differently, in sequence, to compensate for barrel wear).

 

[BoydAllen]

I believe that one thing that you might do is to smooth up the throat. A friend did a small experiment that seemed to work out. Essentially it involved smoothing out the edges of fire cracking, which had a positive effect on jacket fouling. I can tell you more if you are interested.

 

[DaveTooley]

I've always managed wear with seating depth changes. Once I find a bullet the barrel likes I've never had to change.
I do manage heat checking as the barrel ages.

 

[LCazador]

Less heat and a shorter not longer bullet can help with a worn barrel. A shorter bullet with a faster powder will produce less friction and heat. Of course proper cool down is in order with a worn barrel. And smoothing down the firecracks will help by reducing the amount of bullet jacket deposit and friction.

 

[davidjoe]

I believe that one thing that you might do is to smooth up the throat. A friend did a small experiment that seemed to work out. Essentially it involved smoothing out the edges of fire cracking, which had a positive effect on jacket fouling. I can tell you more if you are interested.

Yes, absolutely, but at your leisure, merry Christmas.