I'm posting this not to cause any further consternation among some but simple because in another thread (now locked) I said I would post the results of my testing my 30x60 XCB rifle with the 30 XCB bullet at 2900 fps at 600 yards. This is simply the facts and results of that test I said I would report on as many have expressed interest to see the results.
The weather cooperated with a beautiful morning here in Arizona. Was at my shooting place in the desert at daybreak and got set up so 1st shot went down range at 0730. Temperature was 45 degrees and when I finished shooting at 1030 it was up to 60 degrees. The humidity was 25%. I staked the target (older NRA “B” target for 600 yard) on the hillside and put up the wind flag. The wind was very calm to begin with so I was able to get off 4 groups (three 10 shot and one 15 shot) before it got squirrelly. Even at the 2900 fps I’m shooting the 30 XCB at out of my 30x60 XCB rifle given the low BC the wind really pushes the bullet around at long range.
Attachment 216131
Off to the right of the target a couple feet you can see a little black rock in the road. That’s my “spotter” target. About 2/3 the way to the flag pole is a couple large powder jugs filled with water, more on them in a bit. Repairing back to the 600 yard firing point I prepared a prone shooting position. From the rifle the target looked like this;
Attachment 216133
I took 6 shots (3 foulers and then 3 confirm) to get “on” the sighter rock and then I put 3 rounds into the black powder jugs of water. I should have quit then and rebuilt my shooting position as I had just set the front rest on the bare rocks/gravel. That didn’t work well during the next 10 shots on the target as the feet of the rest dug into the ground. I knew I had dropped on down out of the group as the rest was not solid at all so I called that shot. I then went up and checked the Target and sure enough there was a shot down and away. Here is the target. The 9 shots that were "good calls", even with the unsettling rest, went into right at a 10” group.
Attachment 216135
The ballistics from the “Applied Ballistics” program said 20.28 moa elevation correction was required to go from a 100 zero to a 600 yard zero. I had thus set the elevation on the Leupold 6.5x20 scope (zeroed at 100 yards) up 20 ¼ moa, looked good to me. However, I obviously need to go right ¾ moa for windage. The tears in the target are from rock splatter shooting at the “sighter” rock.
I pasted the bullet holes and tears and repaired back to the 600 yard point and rebuilt my prone position using a slab of plywood for the rest. Don’t know why I just didn’t do that in the 1st place…..
Attachment 216136
It was a much more sold rest and position as the next group demonstrates. I adjusted the windage ¾ moa right…..should have gone another 1 ¼ moa right but what the hey…..can’t complain. The 10 shot group is just under 7”.
Attachment 216137
Pasted those holes and wet back to the 600 yard point. I was waiting long enough between the groups so the barrel would cool and was giving it at least a minute between shots. The third group was interesting because I had given the windage another ½ moa right and then shot 3 “sighters” on the sighter rock and all appeared good. As I settled in on the target the wind flag began to move. I could not feel any wind movement where I was but it appeared a 1 -2 mph wind had picked up coming out of 10 o’clock. I just held steady and shot when the flag was in the same position (condition). In that small amount of wind the group moved 2 moa right or about 12”. The group size was a tudge less than 6”…..that’s moa accuracy at 600 yards!
Attachment 216138
Again I pasted the holes and returned to the 600 yard point. I had 15 shots left and the wind was getting squirrelly now coming in from 11 o’clock and switching back and forth to the 1 o’clock. I left the zero alone and shot the 15 rounds trying to shoot when the wind was the same. I wasn't quite able to do that and the wind caught me several times. I should have given it a half moa more elevation because the head wind caused the bullet to slow down quicker with more drop. You can see the lateral dispersion also due to wind and how the POI dropped. Even so I was pleased with a 9” group with the 15 shots.
Attachment 216139
All that took about 3 hours to shoot the 4 groups. By then, 10:30 am it was 60 degrees and the wind was still switching back and forth. I took 10 shots at the sighter with my suppressed .308W M70 with a M118 White box duplication load (LC Match cases, WLR primers, 41.5 gr IMR4895 and a 174 gr M118 bullet. I hit the sighter rock 6 times. I then shot a few rounds out of my Ruger OM Vaquero 44-40 at a couple pop cans. The morning had gone well.
Oh, almost forgot the powder jugs with water. I had set them tandem so at 600 yards the 30 XCBs would have to go through both. The right bullet was the 1st hit, then the left and finally the center shot. The jugs noticeably jumped when hit, especially the first hit. Here is the front;
Attachment 216140
All three hits went through and through. Here is the back of the rear jug and you can see the 1st hit tumbled in the 2nd jug and burst the side.
Attachment 216141
So that ended a very good morning with the average moa of the three 10 shot groups and the 15 shot last group at 1.3 moa. ……not too shabby for a cast bullet at 2900 fps out at 600 yards……..
|
   
   
|
|
Reply With Quote
Originally Posted by sigep1764
