Extreme Spread is my Nemesis (at least it was yesterday)

[J.Baker]

Blew the dust off the old 22-250 Ackley rifle yesterday and took her out to the range. Last time I had her out was this time last year and she didn't shoot the greatest with the ammo I had (handloads from P.D. trip out west in 2006). I had 50 rounds left from that same batch of ammo that were loaded a little lighter (39.2gr H4350 compared to my usual 39.4gr) so I thought I would take them out and run them over the chronograph to see what was going on. Besides, it was a great excuse to be at the range on such a beautiful spring morning.

http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/RangePic.jpg~original

I started at 100yds and the old girl was shooting pretty good, but it seemed I would have one bullet go astray in each group, a result of that rounds velocity being way higher or lower than the rest.

http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_100yds-1.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/100yds-1.jpg.html) http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_100yds-2.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/100yds-2.jpg.html) http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_100yds-3.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/100yds-3.jpg.html)

http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_100yds-4.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/100yds-4.jpg.html) http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_100yds-5.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/100yds-5.jpg.html) http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_100yds-6.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/100yds-6.jpg.html)

The trend continued at 200 yards...

http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_200yds-1.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/200yds-1.jpg.html) http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_200yds-2.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/200yds-2.jpg.html)

http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_200yds-3.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/200yds-3.jpg.html) http://img.photobucket.com/albums/v632/MrFurious45833/Gun%20Stuff/th_200yds-4.jpg (http://smg.photobucket.com/user/MrFurious45833/media/Gun%20Stuff/200yds-4.jpg.html)


During the course of my shooting I had noticed the velocity seemed to be varying quite a bit, but it wasn't until I got home and downloaded the data to my computer that I saw just how bad it really was.

http://img.photobucket.com/albums/v632/MrFurious45833/th_ChronoData.jpg (http://smg.photobucket.com/user/MrFurious45833/media/ChronoData.jpg.html)


As you can see, Group #4 (String 6) was the only string that was consistent for all five shots and it clearly shows in the group size. Fortunately this was the last of the ammo I had from that batch 9 years ago so hopefully some fresh precisely measured loads will have her shooting in the high 2's and low 3's like she usually did in the past.

[jonbearman]

If you ever shoot old ammo it is wise to bump the seating of each bullet as they tend to weld themselves to the neck. If you bump ,lets say .002 it should be enough to give you the neck tension you started with. By having the welded problem pressures can vary wildly.That may answer why you were getting high ES and SD. A lot of benchresters who preload for a match seat them long so when they get there they can finish seating and have the same smooth release of the bullet during ignition to get optimum performance.

[J.Baker]

I didn't have a welded problem, but I did have a growing problem. This is a compressed load, and after 9 years they grew enough to make closing the bolt fairly stiff on some of them. Discovered that last year when I had it out so I made sure to run this last 50 through my seating die again just to make sure they were where they were supposed to be.