TUNER SCEPTIC NO MORE

[a.JR]

e]

[Robert Chombart]

. My thoughts only for what they are worth.
Keith H.[/quote]

But a fair comment....100% on
T.G.C

[Robert Chombart]

I need a combination that changes very little from say 20deg C at 35% humidity at 8.00 am SAT through to 40 deg C and 95% H at 3.30pm on MON pm which i can get in my area..

Jeff,
.0075 was given as a simple example, and the rlongation is constant at normal temperatures. The ambient temperatures changes you mention are already sufficient for this example


but i do know that you guys are a bit off with .0075 length in the barrel because mine lengthens closer to .012 through to .015(Measured) depending on the shot string,

Extremely interesting, indicating that, from the minimal ambient temperature, you can have a barrel temperature elevation of some 44 to 45°. Thanks for the experience...

so don;t shoot the messenger please.. JR.. Jeff Rogers[/quote]

There is may be some who might think of shooting me too!!!....
R.G.C

[a.JR]

rs.

[Robert Chombart]

) with indicators placed on X and Y axis , the 6061 t6 alloy came up the best and thats what is used today ..JR..Jeff Rogers.[/quote]

Jeff,
Use of 6061 T6 (AlMgSi)? For what exact application?
Would not 7075 (AlZn) T651 not more appropriate
My curiousity is excited...
R.G.C

[Woody_rod]

a.JR,

I think you will find that the whole barrel will be heated by rounds being fired through them. The example of heating the chamber area is probably not very indicative of what happens, although it is interesting to use your mill table for this as a stable base. I know this as I pick my rifle up at the muzzle end to carry it, and is just as hot as the other end. ANd, incidentally, I notice that the action seems to be cooler in comparison - although this is probably just due to material mass vs. conduction vs. time.

By alloy you mean Aluminium? To me alloy could mean any of the materials you mentioned.

Correct me if I am wrong (which happens most days), Robert, that the heating is also along the length of the barrel due to both hot gases expanding, and friction of the bullet passing?

I always find it fascinating that a round can be fired and a few seconds later, ejected and be cool to the touch. I know how this occurs, but still find it amazing.

[a.JR]

rs

[Woody_rod]

Hey Jeff,

Now you have me interested in what you are doing....what are you using the 6061T6 for exactly?? True enough that it is common in AU.

Oh, and I remember Our F class man in WA Bill Hallam talking about tensioned barrels. Said it was done by having a tube over the barrel butting against a shoulder near the action, and had a thread on the barrel end, and a nut to tighten the whole thing to put the barrel in tension. Sounds like an interesting idea.

I have never seen one, although I understand the concept. Any chance of sending me some pics as well?

[Robert Chombart]

Rod wrotes:
Correct me if I am wrong (which happens most days), Robert,

That I know very well!!<Grin>

that the heating is also along the length of the barrel due to both hot gases expanding, and friction of the bullet passing?

Heat is enregy, and only a small part of the calories generated by the powder is used to propell the projectile. An other part goes into the air at the muzzle (sometimes at the back also for some experimenters!!) and the rest is spent in friction, compression and is radiateded through the walls of the barrels.
It is perhaps function of the thermal conductivity of the barrel metal, which could led to think that 416 heats more than 4140 due to the higher thermal conductivity of its Ni and Cr contents, both more condcting than alloyed steel???.
Stainless barrels fans, don't shoot at me (by chance I am protected by distance)!!!..
Also, the poorer fricition coefficient of the ''stainless'' (I prefer to say ''corrosion-resstant'', as the martensitics of the 400 series are not 'Stailesses" as the 300 ones.


I always find it fascinating that a round can be fired and a few seconds later, ejected and be cool to the touch. I know how this occurs, but still find it amazing.[/quote]

The case relatively lower temperature can be explained by the fact thet the gases expands out of it, and is not submitted to friction.
Now, shooting at a fastr rate can make the case ....... hot, as heat transmission is reverted from the hot barrel to the case material (brass with good thermal conductivity too)..Just try to pick a case just coming out of a machine gun, and you will rememeber!!! I knwo, I did it!!!.
There is a solution of continuity between barrel and action, and the later is not submitted to direct temperature, pressure and friction.
R.G.C

[peter t]

Hello shooters
In the ever ending quest for accuracy and sometimes being short of cash I have been playing around with the front sight block on my new
223 F/S barrel trying to make a tunner, with the aid of such specialist tools
hacksaw, flat file and small angle grinder, and a lot of trial and error.
I finally got it to work, shot on the F/O championship target last weekend placed 7 shots inside a 100 mm circle at 800 m the other 3 shots
they were all well inside what would have been a Vee Bull on the F/S target.
So tunners do work and you sometimes don't have to spend a lot of money to get results. Will try it at the shorter ranges next week.
Has anybody tried the same thing? I would be interested to hear how it worked.
Peter T