During the manufacturing process the barrel is rifled by either the button pull method, cut-broaching, or hammer forging. Either way, these are the processes for putting the spiral grooves in the barrel. These grooves force the bullet to spin and stabilize the bullet when in flight. During this machining process, the rifling may not all be at the same height. This is a result of the machining process. A match grade (or custom barrel) us usually hand lapped to smooth out the machining marks. They pass buffing compound through the barrel many times to smooth everything out and remove any burrs.
If you have a hand lapped match barrel, then you've paid in excess of $650 for just the barrel. I have one on a match rifle. Well worth the $$$ for crazy accuracy. Most off-the-shelf rifles don't have a hand lapped barrel, and requires a break-in process. Most MFGs have their own way, but there is a common way.
Part 1. Fire ONE round through the rifle, then clean the barrel. Do this for 5 sets.
Part 2. Fire THREE rounds through the rifle, then clean the barrel. do this for 5 sets.
Your break in process should take 20 rounds. Most will use cheap target rounds since the accuracy is not where it needs to be until after the break-in process.
My Savage 300 WM came in a few days ago and I finally had a chance to break it in and sight in my scope. This is what I'm working with.
* Savage 116 Left Hand Stainless Weather Warrior 300 Win Mag
* Zeiss Conquest 4.5-16x50 scope w/ Z-800 ballistic reticule
* Warne Maxima Fixed Medium Rings and 2-pc Base
* Remington 180gr Core-Loct Soft Points
I'm out at my usual desert spot and started my process. I put up two targets @ 100 yards and two @ 200 yards. I alternated my distances but recorded the improvements of the groups as the barrel was breaking in.
My first group had a pretty large spread. Part of it was the barrel and part of it was my less than stable shooting platform. 4.15" group @ 100 yards sucks bigtime. This was during part 1 of my break-in process. I only fired 3 of the 5 shots on paper. The first two shots, I put into the dirt burm.
On my 2nd group I averaged out the 1st group, made my scope adjustments and took aim at the bull @ 200 yards. Even though I doubled the distance, the improvement there. A 2.05" group is 1MOA. That's what I would expect out of any decent rifle.
The 3rd group, I was finished with the break in and and the group tightened up very well. I expected great results so I moved to a very stable platform for shooting. The results were amazing. An 0.69" group @ 200 yards is 1/3 MOA! That's benchrest accuracy! Yay for Zeiss Riflescopes! Ok, someone above loves me.
I don't think this will ever happen again. The conditions were perfect. No sun glare, no wind, I had an ultra stable shooting platform and the barrel was just broken in. Notice the group was going the opposite direction of the bull. I made my corrections but dial it in backwards, so instead of going towards the bull, I dialed in in the opposite direction.
Group 4 I tried to re-dial my point of impact to hit center. I fired 2 shots to check my elevation, then the 3rd shot was the correction for windage. Although I marked this grouping, it really didn't count.
Group 5 I brought it back into 100 yards. Using my ballistic software, I made an on-the-fly adjustment and shot this tiny group. Compared to my 200 yard group, it was not as good. I should have had 3 bullets going through the same hole giving my 1/4 MOA. I attribute my personal failure on the fact that I fired 30 rounds of 300WM and my shoulder was starting to feel like raw meat. Even still, a 0.65" group @ 100 yards is a 2/3 MOA. I'll take that any day!
The test results point to a very obvious conclusion. If you properly break in a barrel properly, you can achieve the best accuracy the rifle can provide. Thankfully, Savage Arms build some fantastic rifles and with their Accu-Trigger and Accu-Stock the rifle can shoot better than most people. Paired with a top quality optics like the Zeiss Conquest, the package equals a super accurate rifle.