[SirIsaacNewton]

Can someone explain how heat effects a rifle barrel in terms of accuracy and also how a heat sink/thermal dissaptor acts to combat that. Are these thermal dissapators effective. Are they worth investin in? I would also like to get input on black teflon coated barrels and its effect on radiating heat. Thanks for any advice and/or reading material.

[jtischauser]

SirIsaacNewton, on Nov 9 2009, 06:30 PM, said:

Can someone explain how heat effects a rifle barrel in terms of accuracy and also how a heat sink/thermal dissaptor acts to combat that. Are these thermal dissapators effective. Are they worth investin in? I would also like to get input on black teflon coated barrels and its effect on radiating heat. Thanks for any advice and/or reading material.

I am sure there are experts on this topic on this forum that will give you an in depth technical answer but here is my take on the topic. The barrel like everything else expands and contracts as it gets hotter and colder. Any movement in the barrel no matter how small effects accuracy tremendously.

The heat sink is a simple heat exhcanger attatched to the barrel. The barrel transfers the heat to the heat sink through a process called conduction. Since the heat sink has a larger surface area than the barrel the heat sink fins are touching more cool air than a barrel itself would be. The process of convection then takes over and the heated air touching the heat sink rises and carries away the heat thereby cooling the barrel and reducing barrel deflection from heat.

All that and the heat sink can help keep you from burning your hand as quickly if you have a metal handguard and do a lot of shooting.

I don't know what the Teflon does?

[SirIsaacNewton]

jtischauser, on Nov 9 2009, 08:24 PM, said:

SirIsaacNewton, on Nov 9 2009, 06:30 PM, said:

Can someone explain how heat effects a rifle barrel in terms of accuracy and also how a heat sink/thermal dissaptor acts to combat that. Are these thermal dissapators effective. Are they worth investin in? I would also like to get input on black teflon coated barrels and its effect on radiating heat. Thanks for any advice and/or reading material.

I am sure there are experts on this topic on this forum that will give you an in depth technical answer but here is my take on the topic. The barrel like everything else expands and contracts as it gets hotter and colder. Any movement in the barrel no matter how small effects accuracy tremendously.

The heat sink is a simple heat exhcanger attatched to the barrel. The barrel transfers the heat to the heat sink through a process called conduction. Since the heat sink has a larger surface area than the barrel the heat sink fins are touching more cool air than a barrel itself would be. The process of convection then takes over and the heated air touching the heat sink rises and carries away the heat thereby cooling the barrel and reducing barrel deflection from heat.

All that and the heat sink can help keep you from burning your hand as quickly if you have a metal handguard and do a lot of shooting.

I don't know what the Teflon does?

At what temperature is accuracy significantly effected? Around how many rounds does it take to reach that temperature? I keep reading about harmonics of the barrel. I was wondering how the thermal dissipator effects harmonics? I am assuming (which doesn't always lead to the most accurate of results) as the heat of the barrel increases the circular arc that the barrel travels through would increase. That makes sense to me but what about this rigid structure attached to the barrel which is increasing surface area. Does this thing effect the harmonics of the barrel significantly. Heck or Harmonics of any importance whatsoever at the distances usually addressed in a 3 gun match? I have some background in physics (I am by no means a physicist so please disregard the name.) and I would love to hear some details on the subject.

This post has been edited by SirIsaacNewton: 09 November 2009 - 09:43 PM

[SirIsaacNewton]

Well I have been reading a bunch of stuff and if you want something to do I found a pretty cool link that answered some of my questions. I thought the link on page leading to an explanation of pressure pulse was pretty freaking cool. Hope you enjoy http://www.shootings....com/barrel.htm

[kgunz11]

Chris Long is a genius, but you're over thinking things if you're worried about heating a bbl beyond it's realm of acceptable accuracy for most purposes. First of all, every bbl is different. They have their own harmonics which is altered by the bbl heating up which causes what we shooters call "walking". How much it effects any given bbl can only be determined by testing on THAT barrel. Custom barrels are known to be less effected by thermal progression because of the heat treating to relieve stress in the barrels. I have shot strings of fire in my .308 up to 40 rounds in a single string with no POI shift. Then again, after about 30 rounds with a suppressor things start to change, but several things can cause this including the additional fouling in the bbl due to gas blow back caused by the suppressor. At 40 rounds with the suppressor I can start blowing primers.

[kurtm]

I bet the primers enjoy that.

[fomeister]

LOL!

[kgunz11]

kurtm, on Nov 10 2009, 02:57 PM, said:

I bet the primers enjoy that.

The primers don't really like igniting a charge of Varget big enough to launch a 210 Berger at 2710fps, but they get over it.
The Wolf primers do hold up pretty well to a 105gr Berger in a .243 going 3320fps.

[XRe]

Methinks someone missed the clue bus...

[kgunz11]

kurtm, on Nov 10 2009, 02:57 PM, said:

I bet the primers enjoy that.

Quote

Put your mind in the gutter and go re-read Kurt's post...

Yeah, right over my head. I missed that one. You guys are terrible!