americanstrat98
11-30-2012, 07:24 PM
Westcliffe01,
I don't know who you think you are, but I think you're awesome, haha
You are correct, Fire Lapping is great for billy bob, but is not a good technique, in fact it's a little drastic. In order to properly lap a barrel, a lapping guide, hardened steel rod, two vices and a smeltering set-up to make bore laps out of lead. Fire lapping will help a person polish the lands and grooves, but if there is a defect in the barrel it will make it worse.
The object isn't to make the bore silky its to make the bore the same diameter, or have an even taper down the tube. If you fire lap something with a jacketed bullet, then the pressure behind the bullet will force it to take metal away from all tight spots, AND wide spots in the barrel. Do to the nature of copper jackets and pressure, a jacketed bullet expands and contracts as it passes over different high and low spots. SO again, if you have a barrel with a wide spot or gouge in it, then it will become worse, this will lead to gas pressures escaping around to the front of the projectile and will make the flight wobble. It could shoot 1/2' at 100 but at 500 it could shoot 3feet.
Lead lapping is the best way to lap a bore, but to my dismay in the gunsmithing community it is becoming a lost art. and it is an ART! Lead is a dead metal so once it is squeezed down to a smaller diameter it doesn't enlarge again. So what you're doing each time you pass the lap down the tube is you're taking out the tight spots in the bore, After lapping is completed(about 10-12 hours of work) you should have a bore that is more even down its length, or have a slight taper (with lead cast bullets or rimfires you want a taper so the tightest point is at the muzzle).
now, another thing is this, there was a gent a few years back that did an erosion test. he took two bores and measured them (stainless with carbon material). He then proceeded to fire 16,000 rounds out of each barrel, one barrel he cleaned often and the other he never did. At the end he cleaned both barrels and re measured the lands and grooves, and throat errosion, he came up with the conclusion that a clean bore vs a dirty bore does no damage over a lifetime of shooting, BUT let me say that he never put oil, dirt, snow, water, and all the other crap from the floor board of papa's chevy in the bore. It was in a controlled setting. I think we all know that a good clean firearm is a happy firearm and that cold bore shots are risky. Just thought it was an interesting article to share.
I don't know who you think you are, but I think you're awesome, haha
You are correct, Fire Lapping is great for billy bob, but is not a good technique, in fact it's a little drastic. In order to properly lap a barrel, a lapping guide, hardened steel rod, two vices and a smeltering set-up to make bore laps out of lead. Fire lapping will help a person polish the lands and grooves, but if there is a defect in the barrel it will make it worse.
The object isn't to make the bore silky its to make the bore the same diameter, or have an even taper down the tube. If you fire lap something with a jacketed bullet, then the pressure behind the bullet will force it to take metal away from all tight spots, AND wide spots in the barrel. Do to the nature of copper jackets and pressure, a jacketed bullet expands and contracts as it passes over different high and low spots. SO again, if you have a barrel with a wide spot or gouge in it, then it will become worse, this will lead to gas pressures escaping around to the front of the projectile and will make the flight wobble. It could shoot 1/2' at 100 but at 500 it could shoot 3feet.
Lead lapping is the best way to lap a bore, but to my dismay in the gunsmithing community it is becoming a lost art. and it is an ART! Lead is a dead metal so once it is squeezed down to a smaller diameter it doesn't enlarge again. So what you're doing each time you pass the lap down the tube is you're taking out the tight spots in the bore, After lapping is completed(about 10-12 hours of work) you should have a bore that is more even down its length, or have a slight taper (with lead cast bullets or rimfires you want a taper so the tightest point is at the muzzle).
now, another thing is this, there was a gent a few years back that did an erosion test. he took two bores and measured them (stainless with carbon material). He then proceeded to fire 16,000 rounds out of each barrel, one barrel he cleaned often and the other he never did. At the end he cleaned both barrels and re measured the lands and grooves, and throat errosion, he came up with the conclusion that a clean bore vs a dirty bore does no damage over a lifetime of shooting, BUT let me say that he never put oil, dirt, snow, water, and all the other crap from the floor board of papa's chevy in the bore. It was in a controlled setting. I think we all know that a good clean firearm is a happy firearm and that cold bore shots are risky. Just thought it was an interesting article to share.