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July 20th, 2007

TECH TIP–Poor Man's Headspace Gauge

Here is a simple, low-cost way to get reliable readings of case headspace when you “bump” the shoulder back on your 6BR, .243, or .308 Win brass. Credit Boyd Allen for this tip. First, you’ll need one .45acp case, with primer removed. Make sure the .45acp case is trimmed square and that it is round. We recommend you first run it through an expander, then size it, trim it and chamfer. Next, take the .45acp case and slip it over the neck of a fired, unsized case with the primer removed. Align the two cases between the jaws of your calipers and note the length from rim to rim (Top Photo, striped case).

OK, now you have the length for a fired case. Next, take a sized case (without primer) and do the same thing, placing the .45acp over the neck of the FL-sized case (Bottom Photo). The difference between the two numbers is the amount of “bump” or set-back you are applying to the shoulder. Here the difference is .0015″. The amount of bump you need varies with your chamber and your load, but .0015-.002″ is a good initial setting. By using this simple tool, you can avoid bumping the shoulder too much. This will also help you set-up the depth of your full-length die to get the proper amount of bump each time.

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July 20th, 2007

IMR 4007 SSC in 6-6.5×47 Lapua

We had a chat yesterday with Ed Eckhoff, who has served as Match Director for the U.S. F-Class Nationals, NBRSA 600-yard Nationals and other major events held at the Sacramento Valley Shooting Center. Ed has been working with the 6.5×47 Lapua necked down to 6mm. Ed told us he was getting good velocity and stellar accuracy with the new IMR 4007 SSC powder. “I was testing recently at 300 yards, and the first two shots pretty much went through the same hole. The group ended up well under .4 inches. Pretty amazing for 300 yards”. Ed is using 39.0+ grains of IMR 4007 SSC with his own custom-made 108 grain boat-tail bullets. Ed said he can get his 108s well over 3100 fps and there has been no stiff bolt lift and no extrusion of brass into the ejector area. Ed’s big question was barrel life. He asked us–“Has anyone shot out the barrel on a 6-6.5×47 yet? I wonder what kind of barrel life can be expected.”

IMR 4007 ssc

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