Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Rifles, Bullets, Barrels and Ballistics


Reply

Your input desired on design of barrel friction experiment with bullet coatings

 
LinkBack Thread Tools Display Modes
  #8  
Old 11-07-2011, 08:51 AM
Platinum Member
 
Join Date: Aug 2003
Location: NC, oceanfront
Posts: 3,212
Re: Your input desired on design of barrel friction experiment with bullet coatings

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 –by 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 I’ve 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 they’re aiming at)..
I don’t know, maybe the tactical bunch would buy into this kind of stuff.
I can't imagine anyone here taking this seriously
Reply With Quote
  #9  
Old 11-07-2011, 09:23 AM
Silver Member
 
Join Date: Nov 2010
Location: Monument, CO
Posts: 190
Re: Your input desired on design of barrel friction experiment with bullet coatings

Quote:
Originally Posted by Mikecr View Post
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.
Reply With Quote
  #10  
Old 11-07-2011, 12:36 PM
Platinum Member
 
Join Date: Aug 2003
Location: NC, oceanfront
Posts: 3,212
Re: Your input desired on design of barrel friction experiment with bullet coatings

Quote:
Originally Posted by Michael Courtney View Post
We have thought this out carefully.
Yet:
Quote:
Originally Posted by Michael Courtney View Post
Why hasn't this already been done?
It's clear to me that you(and whomever 'we' are) haven't thought this out at all.
It's been done for many decades and you need to at least review the results of it.
Quote:
Originally Posted by Michael Courtney View Post
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.
With this you will have gained nothing(velocity wise) while using more powder(reducing barrel life) to counter reduced friction(which lowered MV), -that you 'think' will provide more energy and increase barrel life!
And you could go faster powder to counter/take advantage of less friction, but faster powders are hotter powders which reduce barrel life. So nothing free there either(surprise)..
Reply With Quote
  #11  
Old 11-07-2011, 05:52 PM
Silver Member
 
Join Date: Nov 2010
Location: Monument, CO
Posts: 190
Re: Your input desired on design of barrel friction experiment with bullet coatings

Quote:
Originally Posted by Mikecr View Post
Yet:

It's clear to me that you(and whomever 'we' are) haven't thought this out at all.
It's been done for many decades and you need to at least review the results of it.
Our review has revealed that most of the "results" are qualitative and anecdotal, along the lines of "the coating caused the barrel friction to be reduced which caused a reduction in muzzle velocity. I was able to increase the powder charge to return to the same muzzle velocity with no signs of excessive pressure."

Please enlighten us by providing citations or web links if solid studies quantifying the friction reducing properties of the common coatings has already been done.

Careful, quantitative studies often solve problems and open doors to possibilities that anecdotal and qualitative studies had missed.

Quote:
Originally Posted by Mikecr View Post
Yet:
With this you will have gained nothing(velocity wise) while using more powder(reducing barrel life) to counter reduced friction(which lowered MV), -that you 'think' will provide more energy and increase barrel life!
And you could go faster powder to counter/take advantage of less friction, but faster powders are hotter powders which reduce barrel life. So nothing free there either(surprise)..
Did you miss the Norma study showing that moly coated bullets lead to increased barrel life at the same muzzle velocity? There's a difference between the real loss of barrel life that occurs going from a standard to a magnum cartridge and the theoretical loss of barrel life that might result from adding a few grains of a faster powder to gain some velocity in the same cartridge. You also seem to assume that only the powder and not the barrel friction contribute to barrel heating. The added erosion and heating from the extra powder may well be offset by the reduced erosion and heating from a significant reduction in barrel friction.
Reply With Quote
  #12  
Old 11-07-2011, 07:08 PM
Gold Member
 
Join Date: Oct 2007
Location: Patagonia Mountains, Arizona
Posts: 752
Re: Your input desired on design of barrel friction experiment with bullet coatings

Could you give a description of your method of measuring "average barrel friction"?
Not all the details, just enough information so we can understand how you can separate the forces of bullet bore friction from the forces of the propellant gas on both the bullet and the barrel.
Reply With Quote
  #13  
Old 11-08-2011, 08:35 AM
Silver Member
 
Join Date: Nov 2010
Location: Monument, CO
Posts: 190
Re: Your input desired on design of barrel friction experiment with bullet coatings

Because of various non-disclosure agreements as well as applicable laws and regulations, we won't be able to discuss the details of the method for measuring barrel friction until we have secured approvals for public release. We're completing the process now of preparing the manuscript for for internal peer-reviews. After internal peer-reviews, it will be submitted for approval of public release. Best case, the method will be approved for public release in December 2011, but it could slip until January 2012.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Your input desired on design of barrel friction experiment with bullet coatings
Thread Thread Starter Forum Replies Last Post
New Bullet Design fariswm Long Range Hunting & Shooting 6 04-15-2009 07:00 AM
New Bullet Design fariswm Rifles, Bullets, Barrels and Ballistics 44 12-06-2008 09:35 AM
New Bullet Design? Captn C Rifles, Bullets, Barrels and Ballistics 2 02-01-2008 07:33 PM
Bullet Coatings Sako7STW The Basics, Starting Out 15 03-01-2004 03:28 PM
Bullet coatings..Danzac, etc. Rifles, Bullets, Barrels and Ballistics 10 05-21-2003 11:45 PM

Current Poll
Do You Think Slingshots Should Be Legalized For Hunting Brown Bear?
Yes - 47.14%
907 Votes
No - 52.86%
1,017 Vote
Total Votes: 1,924
You may not vote on this poll.

All times are GMT -5. The time now is 05:20 PM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC