johnlittletree
Well-Known Member
You can not break in a steel barrel by firing soft copper alloy jackets surrounding a lead core. It is as silly of an idea to anyone that has ever worked with metal. It is like thinking you can run in the air only like upside down and break in a pair of shoes or boots let alone wear it out that way because the air is softer than the shoes and with almost no friction and no measurable impact the shoes would last for ever just running in a handstand position against the air. If the bore wore from that setting it back and re-chambering and re-crowning would do nothing to improve group size as the barrel wears. It is heat, pressure and abrasive nature of the powder under the heat and pressure of the propellant burning. If you wanted to you could pipe that same amount of pressure and heat into a barrel external with out ever firing a projectile down the bore and still wear it out or if you fired wooden or lead bullets. In fact try taking a copper button and attempting to rifle a steel barrel with the same hardness as a normal finished barrel and then come talk to us. If the barrel broke in a meaningful way then it would make hand lapping with a lead slug and "lapping compound" stupid, meaningless and pointless. The lead is not doing the lapping it is used because it is softer than the steel and will some what conform to the bore and act as a medium to carry the support the lapping compound so it can cut into the steel knocking down asperities. Having to lap something is a sign of the limitations of the machining operations and equipment being used or the lack of the producer wanting to hold higher standards of precision surface finish between operations. Lapping is a cheap dirty un-precise method of finishing the machining that was not finished properly in the previous step. So when you have lots of tolerance staking, old equipment that is so worn it can not hold to tight clearances with precision and repeat ability or it would take too long or cost to much do it properly you use lapping.
A good example of this is ring and pinion gears in a car or truck. They are priced to OEM based on how well they are clearance matched and the surface finish. If the precision is high enough you never need to lap the parts and you do not need to sort them to kind of match them latter with color or alpha bit codes. So lapping is used to bring them into specification because it is cheap and fast. The more lapping that is done the more it cost. The ring and pinion gears used in racing are much more precise and have vastly Superior surface finish and the clearance range for the finished gears is much more narrow. This is also why it cost so much for those parts compared to what GM or Ford is willing to pay per axle. Also the clearance of race parts are machined so they are perfect at the operating temp of that part. So if you look at an F1 engine you have to be pumping hot coolant through the engine a good 2 hours before you intend to start it or it will not start because the parts when cold do not have the proper clearances they are not a daily driver so the length, width, clearance and concentrically is set for max accuracy when at operating temps. The main reason for the old break in methods for engines was because of the terrible surface finish on the parts in the engine and in the axle. The axle took far longer to break in than the engine did. It can take up to 10K miles for the gears in the axles and transmission to stop "breaking-in" which is just another way to say "accelerated wear". The better the surface finish the shorter the break-in time needed. So break in is a crude way of doing the final finishing of the parts. When lapping in a valve or gears you do not pass a copper piece though them you simply put the compound on the 2 parts you want to lap. The fact that the bullet deforms going down the bore and bits of jacket are ripped off in the bore tells you all you need to know if you think about it. The two places that see the most wear in a barrel are the throat and the crown and it is not from direct contact with the projectile it is the gases.
Just like their is no excuse with CNC machining for any hi dollar hand gun to need 500 rounds before you expect it to function properly that is absolutely silly and if you applied that to you car it would be like expecting your car not to reliably start or stay running during the first 500 miles because it is not broken in? Your gas stove needing 500 hours of use before you could count on it to light and maintain a selected temp! Maybe your computer needs to break in let those electrons and 1's and 0's break in. You either follow engineering standards and science fact or you believe in voodoo which is faith based but chose one do not select which ever one is the most convenient at the time! A barrel is either a shooter or it is not and if you have to go and add "accelerated wear" to make it shoot well you will also by default have shortened it's useful accurate life cycle because you can never take away material in a very uncontrolled way and improve the quality of the part and it's fundamental level of precision machining! If the barrel requires a lose fit than what was specified on the blue prints and hopefully held to print by the manufacture that means there is an issue with the specification not be the proper specification for max accuracy. That is why you saw all kinds of games being played with bullet dimensions when Palma was huge because the host nation had to supply the ammo and if it was larger or smaller than the standard it could really hurt people from other nations with bore dimensions built to a different standard. The second you start to use a machine it is all down hill. The best performance usually happens as it is wearing out there is a sweet spot along the path from new to worn out it is not because of breaking if it was that would mean you were breaking in the barrel every time you shot it all the way up it reaching the point of being too worn. Likewise the sweet spot is not after 50-150 break-in shots it is normally hundreds to thousands of rounds latter. If you look at the barrels that produce great results for F-Class and High Power it is not at all the same type or brands of barrels that produce the best results for BR guys. Likewise the useful accurate life is not remotely the same from one shooting sport to the next.
In fact even with the preferred barrel makers every barrel is not a zinger and often a truly competitive BR guy might have to go through 3-4 barrels to find one that really shoots! Brux even tells you that if you get a barrel that is not a shooter to let them know and they can get another one out to you! It is not that they do not have industry standard quality control I assure you they do. Likewise Hart barrels tend to produce some really good shooters from day 1 but I have never gotten long life from Hart barrels which is why you see so many used Hart barrel on the used market usually in large heavy profiles and usually in BR chambering. I can not recall ever seeing a serious BR guy with a Douglas barrel or a Brux and never with a CHF barrel ever not in the USA. You do not see a lot of Hart barrels in hunting circles or in tactical practical shooting sports either. You can not even get mass produced rifle OEM's or custom barrel makers to agree on a universal break-in procedure.
When you can not find engineering notes or University Research on an engineering problem it is not a good sign. That means it is someones opinion and not based on facts ie hard data under test conditions with a large sample size. When experts can not agree remotely on a topic it is likewise not a good sign.
