Originally Posted by Mikecr
So it sounds like your objective to increase energy without increasing capacity, powder amount, recoil, or noise, or reducing barrel life -while also extending gains from longer barrels Ėby reducing bullet/barrel friction..
Have you really thought this through?
Why do you think these things will result?
Is there basis to date from friction coatings already in use?
The only real gains Iíve heard of in this regard(velocity) is with sabots.
But nothing there is free of course.
We know that use of moly reduces MV(for a couple reasons).
We know that reducing friction in itself drops peak pressure by widening the peak, with a bullet further down the bore by that point.
And IMO barrel/bullet friction is not the cause of dropping velocity gain rates in longer barrels, but merely a matter of powder burn rates dropping, with pressures reducing, as applied to greater bore area of longer barrels.
Basically, friction/sealing/expansive area are basic factors with our powder burn rates and resultant muzzle velocities. And the price of affecting these(and each affects the others) is likely self defeating to your objectives, and of no gain to long range hunters(who need to hit what theyíre aiming at)..
I donít know, maybe the tactical bunch would buy into this kind of stuff.
I can't imagine anyone here taking this seriously
We have thought this out carefully.
The next step is quantifying how much friction is reduced by a given coating. If energy loss to friction can be reduced from 200 ft-lbs to 100 ft-lbs in a given cartridge, then increasing the powder charge (or possibly using a different powder) should be able to increase the muzzle energy by 100 ft-lbs with the same peak pressure and cartridge. If energy loss can be reduced from 1000 ft-lbs to 500 ft-lbs then the energy should be able to be increased by 500 ft-lbs for the same bullet and cartridge and peak pressure.
Why hasn't this already been done? I can think of several possibilities. Perhaps no one has had the tools to accurately quantify barrel friction with and without coatings. We have that now. Perhaps there are more commercial gains to be had in introducing new cartridges rather than making the old ones work better. I suspect that reliable gains in friction reduction through coatings require more control over barrel quality and cleaning than can be exercised by an ammunition supplier, so they are reluctant to load ammo much hotter lest a small percentage of pitted or rusty barrels lead to a lot of liability lawsuits.
Another fact to consider is that barrel friction will be highly correlated with fouling. (What other than friction rubs the copper from the bullet?) Fouling is a challenge to quantify, but now friction can be accurately quantified. A coating that does the best job at reducing barrel friction will most likely also do the best job reducing barrel fouling because it will reduce the forces between barrel and bullet which are rubbing the copper from the bullet.
We've worked a bit with sabots and the energy lost to friction with a saboted load can pretty easily be reduced to about 80 ft-lbs. However, maintaining the accuracy needed for reliable hits beyond 200 yards is much harder than with coated bullets. In addition, sabots are a custom deal in all but a few calibers.
Is a 100 to 500 ft-lb gain enough to justify a given coating? It depends on the application. Some match shooters need to stretch the .308 Win or .223 Rem to longer distances, and it might be. I could certainly use 500 ft-lbs more in my long range rigs in 25-06, 6.5x284, and .300 Win Mag, and I'd much rather get the gain from a bullet coating than rebarreling.