Accuracy Issue

[cbass4761]

New member here. Has anyone experienced any accuracy probs with a 1 in 8 twist encore barrel using 240 smks subsonic. I have tried everything i know and my best groups at 100yds are still 2 moa. I seem to be ok for about 4 shots, then my group starts stringing south. Maybe a fouling issue? Any help would be appreciated before my 300-221 becomes a trotline weight.

[justshoot]

I don't know about Fouling ? Everytime I clean my barrel. I am surprised at just what little copper and carbon there is.
I don't use the sierra's though. I been using the Hornady's in 220. I also see a increase in my accuracy when it gets a little dirty too.

I am using Bolt-Action platform, I got 2 other centerfire .30 that eat most my time up. So have not dedicated priority to the 30-221 but I am pretty happy and been getting around 1-moa @ 100 yrd. and been able to keep them in a paper plate for the most part @ 200 yrd.
Myself (IMHO) I got a funny feeling that I am going to have to start Tweaking OAL and Neck tension to get better for the groups but don't quite have the time right at this moment.
I am going to have to get a Neck-Size Die that take bushings like I do with my other .30 cals. in .308 and .300wm. So I can get it tuned and consistent in tension.
I DON'T like the neck size die a I got in the Redding 3-Die set I got. And Especially DON'T like that neck size ball and it size either.
For Neck Sizing. I like the Bushings for Neck size when I Neck Size only I never use the neck ball unless the neck is pretty smashed or something.

ALSO. I find The subsonic platform with the .30 cal. is real sensitive for sure. I find it even more sensitive than subsonic rimfire match. Way more Sensitive in the way of body & trigger Follow-through when firing for groups.
.

[Spook]

Check the length of your brass for starters, I've heard of guys barrels shooting "patterns" due to the brass being too long.