As some of you may recall, I had a post a while back regarding my .243 at 1000+ rounds. Here is the original post:
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1326679&page=1
I now have 1400+ rounds (1472 to be exact). I wanted to give a rundown on what has happened since. At a little over 1400 rounds I decided to shoot two Tubbs TMS rounds and polish the bore with KG (I normally go every 500 rounds before shooting the TMS rounds and polishing the bore). Same process I used earlier. I did this because I noticed that my groups were starting to open up. The gun was still easily sub 1/2 MOA, but keep in mind the gun was a SOLID 3/8 MOA performer when it had fewer rounds. So instead of waiting to do the TMS rounds at 1500, I decided to do it now.
After shooting the TMS rounds and polishing the bore I measured the distance to lands. The lands have now moved by .06" since new. Not to bad considering I shot F-Class with this gun. At 853 rounds the throat had moved .033".
I then decided to do an OCW load development to see if changing the powder charge would bring the accuracy back. I still used H4350 but I seated the bullets out to the point in which they were .015" from the lands. This resulted in an OAL of 3.245" (measured with a Sinclair comparator). At this length, they were a little longer than what would fit into the mag. The OCW testing showed that 42.3 gr and 42.9gr were pretty good (not 3/8 MOA good, but sub 1/2 MOA). BTW - 42.3 is what I was shooting after I had 1000+ rounds down the tube.
I then decided to take these two loads and do another test in which I varied seating depth. So I did .005", .010", .015" and .025" off the lands. Here are the targets:
42.9gr H4350 (speeds avg. 3006 fps)
42.3gr H4350 (speeds avg. 2980 fps)
The 42.3 gr load with the 115 DTAC's seated .025 from the lands produced the best group at .204" (3 shots).
What I found interesting is that the DTAC's (like most Sierra bullets) prefer more jump. It looks as though I will be sticking with my 42.3gr load with an OAL of 3.235" (measured with a Sinclair Comparator). This just fits into the AI mag.
Hopefully people will find this interesting and informative.
BTW - What works in my rifle MAY NOT WORK IN YOURS. USE AT YOUR OWN RISK. All loads were done using Boron Nitride coated bullets.
Thanks,
Tony
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1326679&page=1
I now have 1400+ rounds (1472 to be exact). I wanted to give a rundown on what has happened since. At a little over 1400 rounds I decided to shoot two Tubbs TMS rounds and polish the bore with KG (I normally go every 500 rounds before shooting the TMS rounds and polishing the bore). Same process I used earlier. I did this because I noticed that my groups were starting to open up. The gun was still easily sub 1/2 MOA, but keep in mind the gun was a SOLID 3/8 MOA performer when it had fewer rounds. So instead of waiting to do the TMS rounds at 1500, I decided to do it now.
After shooting the TMS rounds and polishing the bore I measured the distance to lands. The lands have now moved by .06" since new. Not to bad considering I shot F-Class with this gun. At 853 rounds the throat had moved .033".
I then decided to do an OCW load development to see if changing the powder charge would bring the accuracy back. I still used H4350 but I seated the bullets out to the point in which they were .015" from the lands. This resulted in an OAL of 3.245" (measured with a Sinclair comparator). At this length, they were a little longer than what would fit into the mag. The OCW testing showed that 42.3 gr and 42.9gr were pretty good (not 3/8 MOA good, but sub 1/2 MOA). BTW - 42.3 is what I was shooting after I had 1000+ rounds down the tube.
I then decided to take these two loads and do another test in which I varied seating depth. So I did .005", .010", .015" and .025" off the lands. Here are the targets:
42.9gr H4350 (speeds avg. 3006 fps)
42.3gr H4350 (speeds avg. 2980 fps)
The 42.3 gr load with the 115 DTAC's seated .025 from the lands produced the best group at .204" (3 shots).
What I found interesting is that the DTAC's (like most Sierra bullets) prefer more jump. It looks as though I will be sticking with my 42.3gr load with an OAL of 3.235" (measured with a Sinclair Comparator). This just fits into the AI mag.
Hopefully people will find this interesting and informative.
BTW - What works in my rifle MAY NOT WORK IN YOURS. USE AT YOUR OWN RISK. All loads were done using Boron Nitride coated bullets.
Thanks,
Tony
