Range Report AW home barrel job, 6.5CM

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  • Sep 6, 2006
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    Eastern Sierra
    I did my second home barrel instal recently. I used a PT&G saami 6.5 CM reamer. I had an old .260 barrel which had too tight a chamber to accept lapua .260 brass, so it was due for an update. Its a Broughton 5c, 8 twist, which had 1500 rounds through it, and one of the most accurate and forgiving barrels I've ever had. I also wanted to try out a new muzzle brake I got from Muzzle brakes and more. It's a .875" 3 port.

    I started by installing the brake. It went well, and I found the bore of the brake to be extremely concentric with its threads and shoulder. Took less than .001" of boring to clean up all the baffle holes.

    The chamber end didnt go quite so well. I was using a different carbide insert(seco instead of carmex), and for whatever reason it began to chatter a bit. I reached the target pitch diameter before I could get rid of it. Cutting the chamber with the new reamer went really well. Cut like butter. I made myself a new gauge for measuring headspace and barrel/receiver indexing. That was a big help. I didnt have that last time. I also used a reamer stop for depth of cut, which also helped a lot.


    I'll post more pics and results below.


     

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    Chamber end photos
     

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    Horrible shitty conditions at the range, but i really wanted to try the thing out.

    The barrel was headspaced short in preparation for the Lapua 6.5cm brass, which at the time I hadnt received yet. Its a few thousandths shorter than virgin hornady.

    I tried two bullets, 123 lapua and 140 eld. All with virgin brass. I fl sized it and inside neck chamfered. There was no other sorting or preparation to the bullets or brass.
     

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    This was a seating depth test i did at distance. The first three pics are the same test fired three times. Left target is .040 jump, then .030, .020, and .010. Three round groups throughout. The fourth test was the "touching" loads, with the right target showing two groups. The upper is a five shot group with one round from each load. The lower is three .030" loads that were baked in the sun for an hour. They were about 40 deg hotter, and averaged 10 fps faster. Not sure why the last round went high. It was exactly the same speed as the others.

    The range is 640 yards. The load is 123 lapuas, 43 gr h4350, br-2's, and bullet jumps from touching to .040 off, and 1X fired hornady brass, no prep.

    Ive never done a seating depth test quite like this. Interesting that the barrel doesnt seem to care much. The last pic shows the velocities for every round fired. Amazing that the hornady brass will produce spreads this close. They have the worst neck wall variances of any brass ive ever used. .0015 out of the same box.

    pics uploaded out of order, but are captioned if you open them up.
     

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