Re-barreled 7mm RUM Accuracy

Discussion in 'Reloading' started by Doug in Alaska, Aug 20, 2010.

  1. Doug in Alaska

    Doug in Alaska Well-Known Member

    May 31, 2009
    I just got my re-barreled 7 RUM back from Hart. Since I had 30 rounds of loaded ammo I was using with the original barrel I took it to the range today to burn up. The load is 85 gr. of RL25 behind a 168 gr. VLD. I shot ten, three shot groups. The groups didn't impress me, running around 1 1/4", and I figured the new barrel just didn't care for the load, or perhaps the VLD bullets. What did impress me was the last two, three shot groups, these groups were very close to being one hole groups. Does this sound odd? Any ideas? I didn't clean the barrel as frequently during the end of the session so thought perhaps it was shooting better as it fouled more but when I did the final cleaning, there was hardly any fouling. Maybe I should load a few more rounds of this particular load and see if it continues to shoot like it did during the last two groups?

    The barrel is free-floated in a HS stock and had the action worked over while Hart had it.

    Thanks ahead of time.
  2. Coyboy

    Coyboy Well-Known Member

    Jan 30, 2005
    Doug, almost seems that this could be a bit of a phenominon with the button barrels.

    I have just started shooting a 300 rum carry rifle I built with a benchmark barrel, I loaded up 6 different loads with 2 different bullets 5 of each.

    Shot about 9 rounds last night then took it to the shop for a good cleaning today. (very quickly cleaned, I must say) Those first 9 were not too impressive just a bit over MOA at 100 yards.

    Tonight I shot 3 ,3 shot groups all under 3/4moa. 2 with berger 210 one with 208 a-max. I then put 3 shots on steel at 400 yards.

    I'll clean it again and give it another run this weekend. Once it sits at 1/2 moa I'll be satisfied for my type of hunting.

    The last 300 rum I did on a button barrel started life with the same load it finished with. The first time out at 100 yards it was shooting right at a 1/2moa.

    About 50 rounds latter that same load was shooting under 1/4 moa at 300 yards in faverable shooting conditions.

  3. J E Custom

    J E Custom Well-Known Member

    Jul 29, 2004
    New barrels need time to break in and even if you don't do a break in they still need to be
    shot and cleaned a few times.

    I have found the best accuracy between 10 and 20 rounds if the break in procedure is used
    and 20 to 50 rounds if not.

    Factory barrels can take longer(More shots).

  4. Doug in Alaska

    Doug in Alaska Well-Known Member

    May 31, 2009
    Thanks for the help guys. After reading your comments, I'll definitely test this load more before giving up on it. I have a ton of .284 bullets so I wasn't too concerned about the groups I was seeing. But wow, if this load continues to group as well as the last two, it will be a keeper.

    J E Custom,
    I'll admit, I wasn't as anal about the break-in process (clean, shoot one, clean, shoot one, etc.) as I was the last time I broke in a custom barrel. I can remember shooting new rifles with factory barrels when I was a kid and only cleaning when I brought the rifle back to house. Some of these rifles were tack drivers. Of course, my eye sight was probably much better back then! Thanks for the info regarding break-in and accuracy, it is much appreciated.

    Let us know how your next trip to range goes with that 300. I'm not sure how many of my rifles are button barrels, never paid it much attention. Maybe this is the first?