Haven't shot the 25SST much since hunting season so I pulled it out at first light this morning and sent 2 shots down range at my 865yd plate. Wind was 3mph @ 4cl
group had 2.3" vertical and 4.5" horizontal.
Barrel has 1,179 rounds through it now and throws my 3rd shot now so I just shoot 2 since it's a hunting rifle with a sporter contour Bbl and I usually just do cold practice anyway.
I was about a quarter minute low. So I put on the magneto speed for 3 shots to check velocity and those 3 averaged 3133fps, ES of 23 with my standard load of 58gr of H-1000 with the 131 ACE. That made since because the velocity was at 3170, looks like the barrel has lost some more velocity. At ~950 rounds my velocity with this load had dropped from 3230 to 3170 and now with more wear and tear it has dropped a little more. Again the barrel length is 26" and the twist finishes at 7.12"
I then let it cool about 2 or 3 minutes then sent 2 shots at the 1308 yard plate, no sighters sent before hand either. Wind was 5mph @ 3cl, I dialed 2.5 moa right and 29.7 moa up. First shot landed just above the bullseye. Second shot landed low and right about 1.2 moa for 2 shots. The low shot is usually what my 3rd shot does so it makes me think I didn't give the barrel enough time to cool because even at this distance and round count it stacks the first 2 shots quarter moa in decent conditions. The shot to the far left was from my 260 Rem about a week ago so ignore it. And all the splatter is at the top right is just from so many built up layers of paint.
Below is what it usually does at 1308 stacks the first 2 high and throws the 3rd shot low. This target was shot in early January.
After that I drove down and painted those plates and some others.
Drove back to my shooting position and set up to send 2 shots at my 755yd plate. At this time the sun was well over the horizon and right in face and starting to see heavy mirage wind was 6-8mph @ 4cl. I didn't take a picture of that one but the 2 shot group had 0.5" of vertical and 6" of horizontal.
Then I thought I would try some N570 as it showed a lot of potential for velocity when the barrel was new but all I had ever done was Pressure test it.
Below is the original pressure test with N570 when the barrel had around only 150 rounds through it.
Temp 58*
2.877" +.015"
Fed210
N570
61 3259
61.5 3315
62 3320 C
62.5 3357 C slight primer flattening
63 3385 C Shiny EJector Mark slight primer flattening
63.5 3385 C EJector Mark slight primer flattening powder crunching while seating.
Fast forward again to this morning I decided to load up 63.2grs of N570 and shoot a 3 shot group at 755yards all 3 shots with same piece of brass that started out as virgin unfired, reloading it in between shots. At this time wind was switching direction and blowing 8-10mph, sun in my face with heavy mirage. I left the rifle zeroed for my H-1000 load which requires a dial up of 12.2MOA at 755. So with this n570 load which I knew would be running quite a bit faster I dialed 11.2 Moa and sent the first shot which was lucky enough to land on the edge of the bullseye. The 3 shot group ended up being 9" or 1.13 MOA. Not bad for those conditions, the high round count, starting out with a virgin unformed case, and no real load development done. I will retry it in more ideal conditions. At 62.3grs it's pretty compressed. I'm not using a drop tube but I do have to pour the powder in slow and tap the case a little to seat the bullet. COAL is now 2.917" for ~.013" jump.
By now the wind was well over 15mph and mirage was bad but I wanted to keep running my original case I started with to see how many firings I could get out of it with this 63.2 gr load of N570. I shot and reloaded that case 5 more times for a total of 8 firings with this load which produced 3385fps with a 131gr ACE out of a fresh 26" barrel originally. That is pretty impressive. I was thinking I would get 3-4 firings max. Using the better ADG brass in the 25SST that competes with a 257 Weatherby with the same barrel length using 8-10gr less powder. This single case was not annealed between firings and had to be trimmed at 6 firings. Primers still had round edges and the first shot forming the case was the only firing that had slight ejector flow. I did have some primer cratering. After the 8th firing the base was to work hardened to size back down but the primer pocket is still plenty tight. The last 4 shots I put the magneto speed on to check velocity. As expected due to the high round count it lost some velocity from the original 3385fps when I first pressure tested N570 but it still averaged 3316fps.
Here is that string.
It's makes me think when I re barrel to a 20" that I can still run the 131 at 3250fps in a short suppressed package if the accuracy is there! But the barrel life will no doubt much lower. I took it pretty easy on this current barrel.
These 2 3shot groups are from yesterday at 100 yards when I began to load up ammo with my standard 58gr load of H-1000 I wanted to shoot 2 groups just to make sure everything was ok. First was at my usual .015" jump and the second was at .013" jump just to see if that helped tighten things up any. As usual the wind was blowing 15mph @ 3cl, that's why my groups are 1moa left at 100 yards. Even in those winds it still demonstrates how the rifle will still stack the first 2 shots tight and throw the third now as the barrel has worn. And even when the barrel was new it still only averaged 3 shot groups in the .3s-.5s at 100yards but like it does now it stacked the first 2 shots but didn't throw the third as far as it does now.
Some of these groups are not to impressive I know. My point with this long winded post and thread was to show the progress of this rifle as the round count increased. And show that it is still capable of making precise long range cold bore kills on game. I will probably change the barrel out before it is truly done and not capable of making long range cold bore shots. The bore looks pretty rough through the bore scope right now but that's fine. Though it has not been as accurate as some of my other long range hunting rifles it still accounted for a lot of long and short range harvest over the past 3 years including a one shot DRT kill on a whitetail doe at 1085 yards.
