Understanding Pressure
- Thread starter orkan
- Start date
Really
Are you sure the smith isn't polishing the chamber to remove tool marks
Larry…. a reamer is a cutting tool, and leaves tool marks.
I want 100% contact between the case and chamber, if I had cross hatch in the chamber and the case decided to slide I would not have 100% contact, I would have a case that had brass sheered form the case with the cross hatching.
I want a die that is as smooth as glass for the same reason, cases I have stuck in my dies did not get stuck because the die had cross hatching, the cases stick in the die because of 100% contact between the die and case.
F. Guffey
I recommend you read the article . You see the first thing they talk about is lube between the case Like water - oil -and solvents . The cross hatch is put into the chamber to give it a place to go . It is good article . Larry
I recommend you also check your reloading dies all mine has across hatch in them . Two different reasons for them one holds lube the other is for removeing it . Larry
Are you sure you aren't confusing your engine experience with your reloading experience? Cylinder bores are crosshatched by design to hold oil to lube the rings. a crosshatch in the chamber would also hold dirt and oil and be detrimental to a good grip for the case on firing. The chamber, just like the bore, needs a happy medium between polished and rough. Too far either way could cause you problems.
Savagedasher; thank you, when I apply the brakes on anything I drive I want 100% contact between the friction surfaces, when I apply my brakes I do not want to get into an emergency situation unless I have 100% contact between the road and tire..
I do not want to trap air, lube, water or oil in the hash mark finish, by design the hash marks will trap the air, lube, water and oil. If the surface has a glass finish there is not place to trap anything.
Again, I do not want anything between the chamber and case but air, I do not want a lot of air and then it goes to fluids and things that flow. Air is a fluid because it flows, air is a compressible; when I pull the trigger air gets out of the way and if is does not is can be compressed. Oil and water are also fluids, both flow but it is not possible to compress water, it is not possible to compress oil, if my chamber has cross hatches oil and water will act like ball bearings; and that is something I try to avoid I am the fan of cutting down on all that travel.
"Again", I do not want anything between the chamber and case but air"; I want the air I have between the case and chamber to be clean air, I do not want dirt, grit and or grime between the case and chamber because when the air leaves the dirt, grit and grime leaves with it. Dirt, girt and grime can not flow as fast as air.
F. Guffey
Normally 180 to 320 grit And the cross hatch is from moving the paper in and out from the barrel turning. Hunting guns the finish can be done with 120 . Larry
i take you must of drove slick tires on a wet road . I like tread myself . Larry
Sorry if you feel I hyjack it . It was clear to me that lube water and solvents were a major problem. Sorry Larry
Maybe, and if it's related to chamber finish is that not worthy of a separate thread with a link back to the article and then fully explore any chamber finish discussion. Don't get me wrong, I think the chamber finish topic is well worthy of further discussion as many appear to have different opinions about it. Me, I think they should be smoooooth but not polished.
Finish is different for the way the gun is being used. Larry
A wet road is one thing and then there is ice and snow; When it comes to ice I prefer siping.
http://sipers.com/about/
And then when it comes to walking on ice I prefer knobblies made with primers embedded into rubber soles.
F. Guffey
I like for the light to reflect off of the chamber wall without distortion, I do not like the dull finish and the light will not reflect if the chamber wall is not smooth. I clean my dies with a towel on a dowel. The towel is embeddable, the case is embeddable, I like that. The embeddable case eliminates the need for the cross hatch patters in the chamber, the cross hatch provides a place for dirt, grit and grime to hide.
F. Guffey
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Before you start thinking you know the gospel on the relationships of pressure, chamber finish (surface texture) and brass you should take a look at Varmit Al's pages. In particular check out the following topics.
1. 243 Model 7 FEA (FEA = finite element analysis)
2. Rifle action stress
3. Rifle chamber finish
4. Friction Test results
If you are not a mechanical engineer a lot of the language may be new to you. However his methods of analysis are common place in mechanical design today and are used in every company that does any sort of critical mechanical design.
I have argued these topics many times with people who insist that it is important for the case to grip the chamber.
It is unreasonable to expect your brass to be a mechanical brake in order to protect your action.
Your action should be capable of handling the firing loads without regard to the brass gripping the chamber simply because solvents or rain may get into a rifle chamber. Your rifle should not be damaged due to a small amount of liquid in a chamber or on a case.
If you use your brass for a brake you will on the path to case separations.
A very small amount of water or lubricant (flim) will not hurt a thing. In fact the Japanese, Dutch, the US and other countries have used oiled, waxed and greased cartridges to aid extraction in automatic weapons. HK and others even flute their chambers to insure cases are easy to extract.
If your bench rest action cannot handle a slight film of solvent left in the chamber by accident you probably should find a more rugged action.
Yes, If your chamber, bore and ammo are drowned in liquid you might cause a bore obstruction that damages something but I am not advocating that.
Anyway he covers analysis of a Rem 7 action and the effect of surface texture of a rifle chambers at several several values.
1. 243 Model 7 FEA (FEA = finite element analysis)
2. Rifle action stress
3. Rifle chamber finish
4. Friction Test results
If you are not a mechanical engineer a lot of the language may be new to you. However his methods of analysis are common place in mechanical design today and are used in every company that does any sort of critical mechanical design.
I have argued these topics many times with people who insist that it is important for the case to grip the chamber.
It is unreasonable to expect your brass to be a mechanical brake in order to protect your action.
Your action should be capable of handling the firing loads without regard to the brass gripping the chamber simply because solvents or rain may get into a rifle chamber. Your rifle should not be damaged due to a small amount of liquid in a chamber or on a case.
If you use your brass for a brake you will on the path to case separations.
A very small amount of water or lubricant (flim) will not hurt a thing. In fact the Japanese, Dutch, the US and other countries have used oiled, waxed and greased cartridges to aid extraction in automatic weapons. HK and others even flute their chambers to insure cases are easy to extract.
If your bench rest action cannot handle a slight film of solvent left in the chamber by accident you probably should find a more rugged action.
Yes, If your chamber, bore and ammo are drowned in liquid you might cause a bore obstruction that damages something but I am not advocating that.
Anyway he covers analysis of a Rem 7 action and the effect of surface texture of a rifle chambers at several several values.
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