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Thread: BCM 18" SS410 Accuracy at 600 yards

  1. #11
    Join Date
    Jun 2006
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    With match ammunition that upper should hold sub 1" grouping at 100. As mentioned the limiting factor is bullet choice and the ability to read the wind and apply the correction/hold. Do take a look at various bullets though-long range they make a big difference. Go to JBM and compare them and see what they do in the wind. I try to break it down further than the stated difference in drift at 600. So let's say drift is 2 mils for a bullet with a full value 10 mph wind, a 1 mph wind moves it .2, at/about 3" drift at 600-so a mis-judge of 1 mph equates to a 3" error on target. For info from Litz's book, 1-2 mph judging error is considered elite. Break it down further-if one bullet drifts .2 mil less than the other, that mis-judge above cost you close to a 1/2" less on target at 600. Doesn't sound like a lot but they (variables) all add up.
    Bottom line-find an accurate and efficient bullet, drive it hard (fast)and read the wind well.
    Check the new tipped SMK and/or the 75 Hornady BTHP since these are going to be mag length more than likely. Single feed-75 or 80 grain AMAX
    Factory 77's-Blackhills
    Factory 75's-Hornady match
    While I can't speak for the new tipped match kings, the 75 Hornady BTHP at equal velocity will be more efficient than the 77 SMK-the numbers don't lie

    JBM run theory numbers 10 mph full value wind at 600 @ 0 density altitude
    77 SMK at 2900 fps(MK262 from my 24" bolt) 1.9 mils
    75 Hornady BTHP match (factory) at 2750"" 1.8 mils
    80 AMAX slow-2585 (reload) -1.7 mils-these are single feed
    Big thing is look at the 77 smk velocity-that's smoking-if I increase the velocity of the other two-very doable-the 77 smk can't keep up ballistically.
    the 77 smk at 2800 is 2 mils and at 2600-2.3 mils

    Run the 1000 numbers and you see the 77 smk is an ok bullet, again the 75 bthp and or 75/80 amax is much better, no direct experience with the Bergers other than with .260/.308
    GET IN YOUR BUBBLE!

  2. #12
    Join Date
    Nov 2013
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    Quote Originally Posted by zandander View Post
    Weren't they doing some of that with a 14.5 barrel too?

    Sent from my Nexus 6 using Tapatalk
    That would be crazy where is that link at!

  3. #13
    Join Date
    Dec 2008
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    I bought a stripped BCM 18" SS410 barrel a few years ago that I built into an upper myself, including drilling/tapering the GB pin hole. It just so happens that the longest range I have access to around here is 600 yards. I can ping a 6" gong consistently at that distance. I have not shot groups that far though. This is with factory Winchester Ranger 69grn match. I have some hand loads in 77smk ready to go test with but haven't had the time lately. The BCM barrel is good stuff.
    By the by, using a Leupold scope I zeroed at 100 yards and using a ballistics calculator dialed in for 600 and was pretty much there. It's just always windy at this place which plays with your shots some.
    Last edited by jhurt; 04-14-15 at 02:51.

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