taw

I just wanted some opinions on how many rounds need to be fired thruogh a new gun before it is considered broken in and will start throwing good groups. The gun in question is a 300 RUM. Thanks in advance for any advice.

vangunsmith

Bigcountry is the one to ask about that one! He has one,and can tell you all about those big boys. Usually on most guns from 200-300 rounds.I just finish building a 243 and have got some groups as low as .330 to.890 with less than 40 rds through it.Just imagine what it might do when the barrel settles in?? But Bigcountry can tell you,im him. vangunsmith

crimedog

Everybody has different opinions, whether it's fire one round and clean, fire two rounds and clean and so on. I gauge when the barrel is broke in by the fouling in the barrel for the most part, but no less than 30 rounds and I like to use the heaviest bullet reasonable.

Roskoe

Most premium barrel manufacturers consider a barrel to broken in at 100 rounds. The usual deal is to clean it every shot for the first 10, then every 5 shots for the next 40 - then shoot it as normal after that. I have seen the group size, with the same load,shrink in half from the first group fired (shots 11 through 15) to the group shot at 100 rounds. Some bench rest shooters say that they fully "settle in" at around the 200 round point - they are dealing with a few thousands of an inch better, though.

bigcountry

Well, I have had three of em. I had one factory remington that wouldn't break in no matter what, but shot an honest 1.5MOA consistently. One PSS that broke in about 40 rounds. And then had one built that broke in, pretty well out of the gate.

It all depends. When I say break in, I mean the velocity spreads drop from like 120fps to like 40fps and seems not to copper foul within 5 rounds. I feel pretty confident your barrel is set at 100 rounds especially if it shoots well. Some rough barrels can never be broke in.

stubblejumper

I have two 300ultramags myself and have helped develop loads for two others.All shot decent groups right from the start and none improved very much as the number of shots fired increased.Three of the four did howeverbuild up copper for the first 30 or 40 rounds.Three of the rifles wore quality aftermarket barrels while the fourth was a factory rifle.

bigcountry

Also taw, I believe stubble hit right. A broke in gun won't start getting group size from 2MOA to 1MOA. You might see some real differences at long range, but not 100 yards.

Some guns need 5 maybe 8 fouling shots to start really grouping well and keeping velocity spreads low. I haven't seen this for myself, but John Barshness sure does write about it alot. If I had a gun that wouldn't start shooting well until the 10th shot, it would be fixed or sold. Just my take.

Here is a load that I have seen work well in 2 of my guns and 2 of my friends guns. Seems very dynamic in many guns but you won't be burning up the chrono. Might make it to 3200fps.

93.5gr H1000 180gr Accubond or Partition 215M primer loaded to COL 3.62".

Solitary Man

My advise: just shoot the rifle andthoroughly clean the bore every 20 or 30 rounds. There's no needtowait forit to become "brokenin" before youstart trying to shoot for groups. Practically every rifle I've ever owned has shotquite well from the get-go. This includes rifles that were broken in with the shoot one, clean, shoot one, clean methods and those that weren't.Now I don't bother with it.

crimedog

Tell you what my first high powered rifle was a remington 30.06 BDL, I neglected it as a 15 year old. It shot the best groups of any gun I have owned. I'm so sorry I sold it when I was enlisted Navy. I have a 300 Win Mag that I'm breaking in to this day, 60 rounds and when it stops fouling to the point I deem good I will work a load. A 308 I have has shot 1/4 groups since the 10th round. I depends on the gun and the roughness of the rifling, and I suspect the length of the barrel. When you deem it's broke in, it is.

Superpig

I concur with most of the other replies you've gotten. The one thing I would look out for is if your rifleis a Remington stainless w/factory barrel. I've heard many complaints and seen a few others (3 to be exact) about the stainless barrels on the 300 RUM's being rough. Of the 3 I've seen personally all three were the LSS versions of the Rem 700. Two happen to be personal friends that reload and couldn't get the guns to shoot well or quit heavily fouling. Both of these guys shoot 1 round and clean until the copper fouling resides. One of the gentleman went at least 70 rounds before the copper fouling died down and the other gave up and had the barrel fire lapped which seemed to take care of the problem. Both to get the rifles to shoot well had the actions bedded and the barrel's free floated. Trigger adjustments were done by themselves. One of the rifles turned out to be a barn burner with 200 gr. NPT. I mean honest 3/8-5/8" groups consistently. I believe he is using Retumbo as his powder. This happens to be the rifle that was fire lapped. The other being my cousin's shoot pretty decent but not near the 1st rifle. His seems to like the 180 gr. A-Frame better than the Partition's at least and I think he is using RL25. He gets consistent groups of 1-1/4-1-1/2" at 100. The good thing about his rifle is that it will consistently group under 2" at 200 yards. I guess it takes more than 100 for his A-Frames to settle down.