I encountered some issues shooting today. I believe I know the cause, but I am not certain. I would like someone who knows more than I do to confirm my suspicions, or tell me I'm full of shit. It was 10 degrees today and the station pressure was 29.15" of Hg. I am shooting a 115 DTAC out of a 1:8" twist Criterion at around 3050 fps. In the past this bullet has shot really well for me, but the coldest temp I had shot in was 55 degrees.
Today, things were a little weird. I checked my zero at 100 yards and everything was normal. 4 shots in 3/8" with one screw up by me that opened the group up to 5/8" I shot at 400 yards and 600 yards, and I had to add a click to my ballistic calculator output for 400 yards and 600 yards. At 800 yards I was adding two clicks. I thought maybe it was the velocity that had slowed down. I had a lot of left and right misses and a few unexplained low misses at 800 yards, but at 400 and 600 yards everything looked fairly normal. Groups were more in the .75-1 MOA range vs. the .5-.75 MOA range that is usual, but it was also pretty cold. I thought I was just shooting like shit, but then I had a shot drop 2 mils short. My assumption is that the DTAC bullets lost stability.
I have a load with 105 AMAX that I have shot a lot. I am lucky in the fact that the DTAC and AMAX have the same 100 yard zero. I changed loads and dialed what had been good dope before and shot a 4.5" group that was well centered on the target at 800 yards. This is the farthest range I have access to at the moment. I also shot at 100 yards again before leaving to make sure I had a good return to zero. I shot a 3 shot group that was one large hole and was well centered with the AMAX load. I don't think the issue is with the scope.
My assumption is that the 115 DTAC is simply not stable in this air density when driven by a 1:8" twist barrel. I have not confirmed the twist with a cleaning rod or anything, but that is the spec. stamped on the barrel as well as what I ordered. My plan is to simply shoot the 105 AMAX load in the cold, but I've never had a bullet lose stability before and am wondering if I am on the right track.
Both loads are similar. H1000 in Winchester brass in a .243 Ackley. All charges were weighed on an ohaus 1010. Cases have been annealed every firing. My reloading techniques are the same for both loads. I have never had unexplained vertical fliers in this gun before, especially not one that is 2 mils off. Does this sound like how stability issues manifest themselves, or do I have another problem I need to fix? If you think this is something besides a stability issue, what else should I look for?
Thank you for you input!
Today, things were a little weird. I checked my zero at 100 yards and everything was normal. 4 shots in 3/8" with one screw up by me that opened the group up to 5/8" I shot at 400 yards and 600 yards, and I had to add a click to my ballistic calculator output for 400 yards and 600 yards. At 800 yards I was adding two clicks. I thought maybe it was the velocity that had slowed down. I had a lot of left and right misses and a few unexplained low misses at 800 yards, but at 400 and 600 yards everything looked fairly normal. Groups were more in the .75-1 MOA range vs. the .5-.75 MOA range that is usual, but it was also pretty cold. I thought I was just shooting like shit, but then I had a shot drop 2 mils short. My assumption is that the DTAC bullets lost stability.
I have a load with 105 AMAX that I have shot a lot. I am lucky in the fact that the DTAC and AMAX have the same 100 yard zero. I changed loads and dialed what had been good dope before and shot a 4.5" group that was well centered on the target at 800 yards. This is the farthest range I have access to at the moment. I also shot at 100 yards again before leaving to make sure I had a good return to zero. I shot a 3 shot group that was one large hole and was well centered with the AMAX load. I don't think the issue is with the scope.
My assumption is that the 115 DTAC is simply not stable in this air density when driven by a 1:8" twist barrel. I have not confirmed the twist with a cleaning rod or anything, but that is the spec. stamped on the barrel as well as what I ordered. My plan is to simply shoot the 105 AMAX load in the cold, but I've never had a bullet lose stability before and am wondering if I am on the right track.
Both loads are similar. H1000 in Winchester brass in a .243 Ackley. All charges were weighed on an ohaus 1010. Cases have been annealed every firing. My reloading techniques are the same for both loads. I have never had unexplained vertical fliers in this gun before, especially not one that is 2 mils off. Does this sound like how stability issues manifest themselves, or do I have another problem I need to fix? If you think this is something besides a stability issue, what else should I look for?
Thank you for you input!
