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Posted: 12/7/2008 7:09:32 PM EDT
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Okay I know there is some real resentment towards the whole "break in a barrel idea". I have a bushmaster thats chrome lined so I will not bother with this one obviously. But would you clean after every shot to break in a dpms 24" SS barrel? Im really confused, all of the info regarding the chrome lined bushmaster seems to be a unanimous NO, in regards to needing to breaking it in. But the SS barrels people alway argue over. DPMS says to break it in by cleaning after every first shot upt to so many shots etc..etc..
Perhaps its so they can "sell more barrels"..but I really dont know. Any advice? |
| I did the break in process for several years and never saw an improvement. I've since stopped doing it and just clean well at the end of the day using a good copper solvent like Butch's Bore Shine. I suspect most manufacturers only mention "break in" because their customers expect it, despite evidence it does nothing for factory barrels. |
| break in is not like an old car engine where you will ruin it without. It is a matter of getting the barrel as smooth as possible inside so it will be as accurate as possible, but more so that is will fire more rounds before fouling begins to decrease accuracy. The gentlmen above is still doing the right thing, just not trying to do it all in the same day. |
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The reason one would take such care with barrel break-in is to remove burs and chip remnants from machining. Depending on the barrel maker and if the rifle was assembled and test fired by a smith would determine if you should follow a stringent break-in procedure. One of the most important burs to remove is around the gas hole, failing to do so will almost immediately cause a copper blob to form and be rammed by each following round down the bore passed the gas hole causing a nasty erosion grove. Most ARs have them but the severity can be controlled adding accuracy life. Additionally if the barrel was not lapped by the maker or assembly smith then there will also be tooling marks and burrs on the rifling edges and chamber throat and neck protruding corners and the crown might have one as well. So we shoot one and then punch out the bore to try to remove chip and copper residue however if you don't have a bore scope its all guess work.
Is it that important? Depends on the rifle, if its got a chrome bore longevity is the goal not accuracy and normally the bore will get mechanically machined to remove imperfections before the plating is added but adding the plating reduces accuracy since hard chroming uniform thickness is very hard to control, some barrels may get post plating machining to try and return the bore to uniform dimensions but its almost impossible. With the stainless barrels world class competitors pay extreme attention to break-in, David Tubb, mega champion, markets his own kit that is basically bullet shaped cutting stones that pressure lap the bore. The AMU uses a $40k machine to cut blue printed gas holes in between the lands and without a burr or champher. HTH AI AR10-Dan in Ga |
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