bigcountry

When you are shooting alot, especially with a newer gun with a rough barrel, do any of you notice the guns still groups, but alot lower like 2" by the end of a 30 round day? I assume, it has to do with lower velocity due to coppered or leaded barrel.

Picked up a used 300RUM in 700P or tactical, with a Leupold 6X20 VariXIII, bipods, bull barrel, and whole pit for around $1100. Owner said only 20 rounds thru it. Took it to the range Sat., and got 4" groups on the first 5 shots. Disappointed was an understatement. Cleaned with Sweets and it was so coppered up, it took me over half an hour to get out the bulk of it. Guess the previous owner didn't clean out good or know how to break in. So, next 4 rounds was 2.5" higher with around .8 or .9MOA accuracy @100yards. Then next three at 200 yards was 2" groups firing one after the other with no cool down. Don't have a chrony yet, but will in a month to experiment.

BigEd

First it's hard to say, without knowing what the other guy realy did to it. That much fouling sounds like more than 20rds went through it but it's hard to tell. I never had that happen but I suppose it could with a softer copper jacket and a real high velocity. The most I've fired through my 300WMag at one time has been 40rds. What worries me is the groups opening up that much at 200yds, I would expect them to be 1-1/2" or a hair bigger. Is the ammo your shooting factory or handloads? If it is factory I can understand that performance. I've never been a fan of factory ammo for accuracy even the "premium" loads. Your weight of barrel should allow for enough cooling not to affect those groups. I'm thinking the bore may be a little bit rougher than most Rem.s. I'd try another break in session of at least 20rds. If he didn't break it in right it ain't ruined; probably just needs to be cleaned out completly and "re-broke in".

TN_Hunter

Sounds like those first 20 shots were fired with ZERO cleaning! Start from scratch. Clean that bore until it is COMPLETELY copper free. That will probably take at least an hour of constant cleaning with sweets, soaked patch followed by dry patches,keep repeating this process until it comes out completely clean with no blue.
Now you are ready to start over, cleaning between each shot or at least every 3rd shot for 40 or 50 rounds.
as far as groups going low, most guns will shift zeroes as the barrel heats up. Which way they shift has never been predictable for me. But, once they start shifting that particular gun will shift in this same direction every time. Ive seen them walk in all directions, but each gun will walk the same way each time. That much is predictable.

bigcountry

The loads are factory. I am happy with 2" at 200 yards with factories. If I am getting <1MOA accuracy then I should be getting around 1" at 100 and 2" at 200. Throw in wind and the weather, I am satisfied. I always start out with factories and then move to my handloads.

Every one of these new remingtons I see have the roughest barrels I have ever seen under a scope. The BDL I am replacing with this gun, gets copper up and shots start opening at 5-7 rounds and I have 150 rounds thru it. I was going to run the Tubbs Final finish thru it, but I am going to send back to remington first. My handloads are moving at 3100 FPS for 180 Noslers PT so I understand they will copper more. But none of my other 700's copper up this quick. They are 270's and 30-06 however.

stubblejumper

Even my custom 300 ultra with a match grade barrel coppered a lot at first.I cleaned with sweets after every shot for the first fifteen shots then every three for the next fifteen and it slowly improved.After 100 shots copper fouling has diminished to the point where it is no longer a problem.