I am having some problems with my 300 Win Mag. I had a great load worked up for it last August using the Nosler 200 Accubond and RL25 powder. Then the accuracy of that load dropped off. Not sure why. Anyway I have been getting a lot of vertical in my groups, no matter what I try. I have come to the conclusion that it is either me and the way I am holding the rifle (follow through, cheek weld, amount I am pulling the rifle into my shoulder, placement of tock on my shoulder etc) or the barrel is moving in the action threads. Both options are hard to believe. The load I worked up in August averaged 0.59 MOA for several groups at 250 to 400 yards but now no matter what I try I keep getting vertical fliers. The barrel moving in the action threads seems unlikely as well because Greg Tannel did the gunsmithing and he uses the Spirallock thread design which is supposed to prevent that from happening.

Anyway if it is my doing what am I doing wrong? When I get a vertical flier it is much more often low. For example today I shot prone at 250 yards with my bipod and a sandbag under the tock. These 9 shots were fired with the 200 grain Nosler Accubond seated 0.005� into the lands and 79 grains of H1000 powder. First 3 shots were in 0.74�. After cooling I fired another 3 shots. The first shot of the second group landed in with the first 3 shots but the next two shots were lower (shot 5 was 3� lower and shot 6 was 2� lower such that all 6 shots were in 3.9� with 5 of those in 2.48�). Then after cooling I fired the last 3 shots. The first shot of the last group was 3� low also and 2� to the right. The 8th shot was 1� low and 1� right of the first 4 and the last shot went in with the first 4. So I had 9 shots in 4.5� at 250 yards with 7 of those in 2.48� and 5 of those in 0.79�. I kind of had two groups. One group was 5 shots in 0.79� and the other was 4 shots in 2.8� but it was lower. Again if I am causing the low shots what am I likely doing wrong? Thanks for the help, Rufous.

Every once in awhile I also experience what seems to be shoting two separate groups. Two clusters maybe 1" apart at 100 yds. Maybe one cluster has 7 shots and the other 5 shots. Nothing in between. It also is random;like shots 1,2,4,6,8,9,12 in one group and the rest in the other.It has always been a passing puzzle to me ; not one that I gave much thought to. Now I'm curious! roger

could be a number of things.
1. clean the rifle make sure the bore is exceptional.
2. check the action screws 40to 55" pounds on the front
25 to 35" on the rear.
3. check the scope base screws ( should be lock tighted)
4. check the rings. scopes do slip.
5. check the crown for damage.
6. take you bore scope with you to the range(if you have one) check to see if the riflescope is changing.
7. If you have the action bedded make sure it hasnt started to sofen from bore cleaners or oil.
8. check the trigger for consistent pull. make sure the pins are all in place.
does your scope track?
Is the barrel floated?
For long range are you using wind flags?
2to 3" groups at 250yds is still pretty good.
What were the conditions?
Dave