Re: New Savage .308 barrel break-in?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AXEMAN</div><div class="ubbcode-body">i broke my factory barrel in this way. i took it off and sold it then replaced it with a <span style="text-decoration: underline">shilen select match hand lapped barrel</span>.
if i hadnt, i would have just shot the factory one. i dont think i would have ever bore scoped it or paid money to buy tubbs. as far as reducing bore life, you have what, 10K lifetime on a 308 barrel? im mixed about this. on one hand its gonna take alot of copper to wear steel smooth. if the bore is rough, my first instinct is to smooth that down. but honestly, its a factory barrel. even if its the 5R, its a factory barrel. wear it out, shoot it out, sand it down, then buy a shilen. or walther-lothar. or kreiger. or mcgowan. or any of the others that are available. i broke my shilen in with 154 rounds on its first day. no waiting, no cooling. its a barrel. its steel. it wants to be shot. <span style="font-weight: bold">how do they hand lap anyway?
</span>
oh i started with 42g of varget and went to just under 46. i have a feeling that 44.8g varget under a 168g SMK will be the one
oh and yes about the scope. if you have a quality scope, that should not affect anything. look up the US optics tests on youtube. they toss it repeatedly off a stand onto the dirt. they remount it and it hits where it did before they took it off</div></div>
Shilen button rifles their barrels. As some of you know this is a process where a bullet shaped button attached to a rod is pushed through the pre-bored barrel hole. It takes a few passes with different size 'buttons' to get the barrel to the correct size, about .0001"-.0003" under size. Note that each pass through the barrel deforms the steel inside and work hardens it. Meaning you can start with a softer steel (same grade, i.e. 4140 CM or 416R etc. just not tempered as hard) The inside surface of a button rifled barrel is about the hardest you can get. You can work harden, by button rifling, the inside of a barrel much better than you can cut that same hardness of tempered steel. Cut rifling gives cleaner edges (rifling) though.
Lapping:
They then take the barrel and put a plug about 2" up the chamber end and fill that with a lead/antimony/polishing grit alloy with a rod inserted and allowed to harden. This 'alloy' forms to the shape of the barrel. The 'plug' is then pushed to the end of the barrel and pulled back several times, polishing the barrel along the way. It also takes a micro thickness each pass. Making it easier to push and pull the rod, as it brings the barrel diameter out to finished size.
FWIW, Savage does not have "rough barrels" And, I'll say too, no one from Savage is supposed to say that on the phone. They run a "finish button" down their barrels last specifically to help iron out any marks that could have been left from the buttoning process. There's a reason Savage barrels are out-shooting everything off the shelf right now. It's not lack of quality where quality counts. You have to get a good hand lapped barrel to beat one. That's why most of your modern custom barrels don't really need much of a break-in. Again, though, it's the people chasing that tiny little bit of extra accuracy that are going to need it.
With those processes noted, here's what a barrel break-in does. By cleaning the copper to bare metal, you expose more surface in the throat area to the fire following the bullet. The high speed impact of the bullet followed by the lands helps knock down the high spots. I said throat because by the time the bullet gets down the barrel a ways there isn't enough pressure or heat to do the same work that is done at the throat. Which goes back to my saying if you have rotten accuracy due to a rotten job of making the barrel, a break-in isn't going to help you.
All you are trying to do is polish/knock down the very minute high spots in the throat area. If you have to take all day to do this then you need to send the barrel back. It shouldn't ever take more than 40-50 rounds. One other thing a break in helps with is if you have a spot that tends to build up copper fouling on one side of the barrel more than the rest it will help keep the bullet going true down the barrel until that spot gets worn in. If the bullet is deformed in the slightest way it will travel differently out the rest of the barrel. Thus reducing consistency. It's not going to be huge but a wear pattern is created there. You want to avoid that if possible.
<span style="color: #3333FF">Edit:
Somewhere in there I forgot to mention the importance of a clean smooth cut when chambering the barrel. Especially the neck/leade/throat areas. The smoother the better.</span>
<span style="color: #6600CC">Edit II:
Using Tubbs barrel break in bullets might eat a lot more barrel than you may want to give up. They will knock down high spots though.</span>
