Posted: 1/31/2011 5:34:31 PM EDT
| I was hoping that if anyone is going to tri county's 100yd range tomorrow that I could tag along to verify my zero. |
Sorry, work tomorrow... I can maybe come early to the match on the 12th if you wanna roll over there that morning. I'm guessing you wanna do it before then though, eh? I will be there another time at some point in the next week or so. (300blk bolt rifle is done and should be in my hands shortly  ) If there's any other days/times you can go, let me know and I'll see if it'd work out. I usually go first thing in the morning since I get off work at 0700. That way I just head over there for an hour or so before I go home.
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I got a good lead from threads on Snipershide.com. I was shooting a 260 Rem, using 7mm-08 cases necked down, CCI-BR2 primers, 144 grain Lapua bullets, and H4350 powder with between 42.2-42.7 grains of powder. The first loads had the bullets seated too far from the rifling, so I moved the bullets forward so there is only about 5-10 thou jump. Accuracy increased dramatically.
The gunsmith I used told me that usually the 6.5's are very forgiving of bullet jump, and it really won't make a huge difference. But, when I seated the bullets out further, the outside to outside measurement of the groups was around .60 to .71 inch. So, if I take off the .264 bullet diameter, the groups were center to center .336 to .445. Not bad for 36 degrees Fahrenheit with the really stout wind that was blowing, and gusting that day. I only have 65 bullets left, so because I have remounted the scope, I have 5 rounds to re-zero, and chrono. Then I can use the data to run a ballistic trajectory chart. I haven't decided which rifle to shoot on Saturday, but it looks like I'll try and shoot the Grendel for score, and the 260 for a second rifle, if the match director will allow it. The new rifle was really consistent, and that surprises me as the barrel only has 35 rounds through it. I don't expect much out of a new barrel until it has 50-100 rounds through it. I'm not a big believer of break in on high end barrels, and think that break in is largely a waste of ammo, and barrel throat. If you have a rotten throat in the barrel that is the result of poor manufacturing, you might get some improvement, but with a high end barrel, machined the way the Smith I used does it, I think there would be little gained. The gunsmith I used uses a chamber roughing reamer, then a finish reamer. Neither of these reamers does anything for the throat...only the chamber. Then for the throat, he has a number of throating reamers with different ogive shapes. He compares the bullet you want to use with the profile on his various throating reamers, and selects the closest match. Then he cuts the throat to give you the exact amount of jump you want your bullet to have before it engages the rifling. This is the second barrel I have had him do, and he hits the jump spot on each time. The first time I told him that I wanted 10-15 thou jump to the rifling. The rifle came back with 12.5 thou jump...how cool is that? The Smith's name is Dave Sullivan at West Wind Rifles in Erie, Colorado. When I asked Boots Obermeyer (barrel maker) who would do the best job installing the barrel I bought from him, he recommended Dave without any hestitation, and no one else. I have been very pleased with everything Dave has done for me. The work cost me more than I hoped, but exactly what Dave told me to expect. The total cost actually came in a bit less than Dave predicted for all the work, so I am very happy with the cost, value, and the quality is beyond what I thought was possible. |