When is a barrel done?


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gamestalker
April 4, 2011, 02:12 AM
What is a normal 7mm rem. mag. barrel supposed to measure? I have two Rem. 700's, one of which has had around 3 K of maximum velocity loads put through it. The other one has had less than half that of the same type loads. The one with the high miliage was recently measured by smith a while back who said it was done. He took a new rifle of same make and caliber and showed me that a .277" bullet will not fit in the barrel at all. Then he took the same bullet and dropped it in my barrel, and it fell through without any resistence. He said the lands were measured at .2785" and should be no more than .277". I'm not buying though, because the rifle doesn't have any throat issues, as he stated. It doesn't eat brass and the chamber is well within spec, also according to the smith. And it groups tight, to the the tune of under 1/2" MOA's at 100 yds. and when my shooting is up to par, it will do the same at 200 yds.
Is this guy trying to sell me a barrel or is his evaluation consistent with SAMMI standard. I also forgot to mention that the same loads shoot a full 100 fps. slower than through my other newer model with the same barrel length.

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ArchAngelCD
April 4, 2011, 02:31 AM
I know hardly anything about barrels except how to them clean but I do know one thing, if a barrel is shooting .5 MOA it's not shot out. That may not be true for much longer if the numbers you quoted are correct but if it were my rifle, I wouldn't worry until that same barrel starts to refuse to hold 1.5 MOA. Anything under 2 MOA is good enough for hunting IMO. The loss in velocity is only telling you what you already know, the barrel is well used.

joed
April 4, 2011, 06:03 AM
When a barrel is done what you'll notice are fliers. You may still get a good 3 shot group but shots 4 and 5 are off by 1" or more. At this point I replace the barrel.

Walkalong
April 4, 2011, 07:23 AM
The throat area gets burned out. It is almost as important as a good crown. The barrel can sometimes be set back and accuracy restored for awhile.

Groups get bigger. True "fliers" happen more often, or start happening, depending on the quality to begin with.

A bore scope will show this erosion. It can also be measured in how far a bullet must be seated forward to hit the lands now vs when it was new.

Fat_46
April 4, 2011, 07:46 AM
Its a gradual thing. I just rebarreled a Savage 243. The old barrel (a Shilen) was my go-to in the prairie dog fields, and regularly shot less than 3/4" groups at 100 yards for several years. Somewhere around the 3700 round mark it started throwing the odd flyer. I marked it up to something I did, as the net string or 3 were cloverleafs. Took it out again last June shooting pds, and the outfitter I use mentioned the gun didn't seem to be shooting like it did the past few years.

Got back, and took it to the range. Cloverleafs were now the exception, and groups opened up to 2.5-4". I have only shot handloads in the old barrel (70gr BlitzKings over 38.5gr H4895) and was happy with the barrel life. New barrel is a Krieger - but I don't expect significantly longer barrel life.

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