Remington glass bed ?

[EddieHarren]

Does the chamber get larger or smaller due to this heating?

[1doug]

if every thing else is growing then the chamber mut be as well

maybe thats why my brass stretches at different rates [img]/ubbthreads/images/graemlins/confused.gif[/img]

d-a

[J E Custom]

Both the OD and ID increase.

On average steels grow by 5/8" per 100 ft per 100 degrees.

So you can see its not much but it can have an effect,
considering most gunsmiths work in thousands and ten thousands.

on the issue of brass getting larger, yes it can but normally that is caused by letting a round sit in the chamber long enough to heat up the powder increasing
pressures.


Nuff said [img]/ubbthreads/images/graemlins/smile.gif[/img]

J E CUSTOM

[Waltech Jim]

[ QUOTE ]
that's a lot of heat!

[/ QUOTE ]

Some time ago I did some testing to find out how much a Remington lug "grew" when heated. I do a lot of pd shooting and heat my rigs up pretty good at times and was wondering if I needed to address this potential problem. Through the years I have taken temperature readings of the barrel while I was shooting to find out just what temperature I was "running" my barrels. BTW it doesn't take long for you to get pretty good at judging the temperature of a barrel with your hand. I took readings about 2/3 of the way towards the muzzle from the receiver. I found I was usually heating my barrels up to approx. 180 F. Occasionally I would "push" them up to 200 but that was the limit. All of my pd barrels except one are polished. My blued barrel sitting in the sun will easily reach 150F. I had a couple of temperature readings at noon that were close to 180F, this is without firing a shot! I also took some readings of the action along side the forward ring. The action though, stays a little cooler and rarely got above 140F. On my polished actions the norm was about 130F. This barrel heat "research" that I did led me into thermal expansion and bedding questions.

The first thing I did was to remove a remington lug and measure it (in the vertical plane) at its longest point at 70F degrees, reasoning this is close to the usual temp my rigs start at, or this is the temperture at which I bed the actions. I heated up water to 185 degrees and dunked the lug in until the water was again at 185. I used 185 reasoning the lug will cool a slight bit while measuring and maybe get me close to the 180 degrees I was hoping for. I pulled out the lug and quickly measured. I did this many times until I was satisfied I was getting an accurate measurement. The lug grew .0008 of an inch. I did the same thing at 150 degrees for some comparison and found the lug grew .0003.

I then questioned what would the temperature of the lug actually be when the forward part of the barrel was at 180F? So I took a Remington 30-06 barrel and action out of the stock and measured the lug at 70F. I then heated up the barrel to approximately 180 degrees with a propane torch. I moved the torch around until I got the action about as warm as it is when I am shooting (130-140F) and measured the lug. I was hard pressed to find any measurable growth.

I will be the first to admit my tests are not scientific but I came to some conclusions that satisfy ME. So, from my testing I reasoned I was probably giving the recoil lug enough room to move when I bedded my rifles. I put two heavy coats of release agent on the bottom of the lug which I have measured at roughly .0003. I also pillar bed all of my rifles.

Jim

[Dead Beat]

ok i just pulled the barrel out of the stock it come out exceptionally well no pin holes no excessive squese out of the bedding compund. it was about a 15 minute clean up with and exacto knife and sharp wood chisel . i used tge score high bedding compund it says it cured in 24 hours

one question how long should i let it sit before i shoot it its a 243 win. with a heavy barrel

thanks jim

[ QUOTE ]
my tests are not scientific

[/ QUOTE ]

I disagree. Excellent report. You have met the basic requirements for a valid test using the scientific method. You have an experiment design with objective measurements, published your data (which hopefully is repeatable)

I also do temperature experiments/measurements. Right now my favorite tool to measure temp is a Fluke FoodPro IR thermo.


[ QUOTE ]
dunked the lug in until the water was again at 185.

[/ QUOTE ]
The problem with using water to achieve thermal equilibrium - evaporation has a significant impact on temp (drop). A far better approach is to bake the object in the oven.


[ QUOTE ]
180 degrees …. lug grew .0008 … 150 degrees for some comparison and found the lug grew .0003.


[/ QUOTE ]
What's missing now is the length of the lug . The coefficient of linear expansion is well know. With the length of the lug we can see how well your measurements fit with established theory.
[ QUOTE ]
I took a Remington 30-06 barrel and action out of the stock and measured the lug at 70F. I then heated up the barrel to approximately 180 degrees with a propane torch. I moved the torch around until I got the action about as warm as it is when I am shooting (130-140F) and measured the lug. I was hard pressed to find any measurable growth.

[/ QUOTE ]

This is the best info and a great test. You (or me or someone else) should now repeat this, but in lieu of a propane torch, torch off a few rounds (you don't even need to be shooting pd's [img]/ubbthreads/images/graemlins/smile.gif[/img] ) What's also missing is the temp of the lug after heating the pipe/action - and how you measured temp.

I think the best way to measure barrel temp is with
Thermocouples and an A/D converter.
A+ work! Good report.

[davewilson]

i agree with big bore, great report. it's what i was very unscientifically referring to when i said that would take a lot of heat. i would say if you've got it hot enough to expand a few thousands, she's way to hot!

this is what's so great about this site. a question comes up and usually someone has researched that particular item and posts their results so everyone can benefit.