[Beladran]

so sitting here bs'ing with pops we were talking about barrels getting hot and starting the throw shots off target. Said back in the day they would take boot laces with knots tied in them soaked in gun oil and put them in a old coffee can with a little chunk of dry ice, then run it down the barrel(pre barrel snake days) The idea sounds solid

 

[Will_M]

Take this with a grain of salt.

The only problem I see with that is that you are forcing the bore to cool extremely rapidly. Dry Ice stays frozen at roughly -70F. Let's assume that the boot laces don't get quite as cold and stay at about -50F. The bore could easily be 200F and you will be "quenching" the bore, possibly affecting the heat treatment of the barrel.

I'm not sure since I don't know what kind of gun it is, or exactly how hot you're letting it get. But quickly bringing metal from a very high temperature to a very low temperature is only a good thing if you know exactly what it's going to do the hardness of the material.

 

[savageshooter]

my 2 cents, just for target shooting, i leave the breach open and bs let it cool. stainless barrels hold heat bad. now if it were combat or a gun battle, different story.

 

[Beladran]

WILL m. More than likely they were doing this on m60's or 50cals. BUt like you said sounds a little iffy

 

[bubbat]

I've seen people pull dents in cars by heating them then putting dry ice on it, dent will pop right out. Don't think it would be good to put something that cold on a hot gun barrel.

 

[Guest]

I've never seen that done on a .50, 240 or m60. I'm not sure how you would handle the barrel that hot and manage to get the patch through and that would be a pretty bit knot on the .50. You probably would run out of boot lace. Asbestos mitts are pretty clumsy. With that said, I don't think a boot lace would cool it quickly enough to make a difference.

All of those machine guns come with spare barrels so unless you're in a situation where you can't get to the barrel to change it I've heard of canteens being used or urinating on it.

I wonder if he might be getting this confused with a field expedient method of using a bootlace with a knot and some CLP to clean a bore of an M16 or M4.

 

[Rem 3200]

I've never seen that done on a .50, 240 or m60. I'm not sure how you would handle the barrel that hot and manage to get the patch through and that would be a pretty bit knot on the .50. You probably would run out of boot lace. Asbestos mitts are pretty clumsy. With that said, I don't think a boot lace would cool it quickly enough to make a difference.

All of those machine guns come with spare barrels so unless you're in a situation where you can't get to the barrel to change it I've heard of canteens being used or urinating on it.

I wonder if he might be getting this confused with a field expedient method of using a bootlace with a knot and some CLP to clean a bore of an M16 or M4.

+1, also where are you going to get dry-ice in the middle of a firefight? :thinking:

 

[Beladran]

I may have to probe my dads mind a little more on this.. I know he was stationed at thule air base for three years. The place is the northern most US military base. It stays between -40 and -10 pretty much year round. i wonder if they were testing weapons or something to see how they would react to the cold?? idk :scratch:

 

[Rem 3200]

I may have to probe my dads mind a little more on this.. I know he was stationed at thule air base for three years. The place is the northern most US military base. It stays between -40 and -10 pretty much year round. i wonder if they were testing weapons or something to see how they would react to the cold?? idk :scratch:

The cold weather test installation is at Delta Junction, Alaska.

 

[Beladran]

yea at fort greely

 

[PhillipM]

Not mentioned is how well heat from the barrel transfers to the boot lace and how many calories of heat a boot lace can hold. I don't see this as being effective as it also blocks any airflow through the barrel.

Clyde Morgan taught me to leave the breech open with the muzzle elevated, causing a chimney effect. As the hot air in the barrel rises, it draws in cooler air through the breech, cooling the barrel.

 

[Rem 3200]

yea at fort greely

Yep, that's the place. I was TDY there in 1970.

 

[Will_M]

[...]how many calories of heat a boot lace can hold. [...]

Q=mdot*Cp*(T2-T1)

Clyde Morgan taught me to leave the breech open with the muzzle elevated, causing a chimney effect. As the hot air in the barrel rises, it draws in cooler air through the breech, cooling the barrel.

(P2-P1)=C*(p_sub_a)*y*((1/T_out)-(1/T_in))



Sorry I just left thermo 2.

 

[Xd357]

Never heard of that but as Will stated I don't think I'll be doing it.

 

[PhillipM]

[...]how many calories of heat a boot lace can hold. [...]

Q=mdot*Cp*(T2-T1)

Clyde Morgan taught me to leave the breech open with the muzzle elevated, causing a chimney effect. As the hot air in the barrel rises, it draws in cooler air through the breech, cooling the barrel.

(P2-P1)=C*(p_sub_a)*y*((1/T_out)-(1/T_in))



Sorry I just left thermo 2.

Thanks, no problem, I had bone head thermo at MSU a long time ago and have forgotten most of it other than a few principles.

 

[crossedcannons45]

Depends on what type of steel it is and what temp will temper/anneal/case harden etc it. 200 degrees isnt going to do much to change the crystaline structure of SS and it seems to me like the barrel would heat up the lace sooner than a cold (even -50 degree) bootlace would cool that much area.I dont think it would work unless you repeated the steps a few times and I'm not sure it would hurt anything as far as adding stress into the steel (it has a pretty stressful job as it is) based on the "200 degree theory" at least. Though, if it heated up enough to change color it most likely would damage it. Either way, I would avoid doing this

 

[sidroski]

I with the side that says you a barrel would have too many BTU's than a shoelace could absorb. I have heard of them pouring oil over the barrel slowly. Even at room tempature, a heavy oil would absorb the heat. A towel soaked in oil and wrapped around the barrel, taken off and dipped back in the oil to disapate the heat and then re-wrapped would probably do better. Slower change in heat wouldn't harm the barrel either.

 

[Will_M]

Depends on what type of steel it is and what temp will temper/anneal/case harden etc it. 200 degrees isnt going to do much to change the crystaline structure of SS and it seems to me like the barrel would heat up the lace sooner than a cold (even -50 degree) bootlace would cool that much area.I dont think it would work unless you repeated the steps a few times and I'm not sure it would hurt anything as far as adding stress into the steel (it has a pretty stressful job as it is) based on the "200 degree theory" at least. Though, if it heated up enough to change color it most likely would damage it. Either way, I would avoid doing this

I agree. Doing it on a rifle that you're shooting groups out of (maybe 10 rounds at a time) wouldn't be too big of an issue. However I've got longtime friend who's going through his final phases of training that tells me stories of swapping barrels off of M240B's where the barrel was glowing.

It's all about the difference in temperature and the elapsed time of bringing it to another temp.