Help: Sudden negative change in accuracy.

Discussion in 'General Discussion' started by ForgivenAll, Dec 23, 2012.

  1. ForgivenAll

    ForgivenAll Active Member

    Feb 3, 2011
    Merry Christmas to you all. I'm looking for some technical advice here. First, I'll describe the baseline condition then what I observed today.

    Hardware: Savage 112 on a glass bedded laminated BVSS stock, 22.250, 24" varmint profile, Weaver 3-15x50 FFP tactical mil/mil scope on a 20MOA base, Sierra 50gr Blitzking on a load of Benchmark powder, at ~4000fps.

    After trying multiple bullets, powders, and primers I finally worked up the above load last spring with the results I was looking for. Finally ORH. Sweet! Although, as expected, I could see accuracy degrade as the barrel fouled, after cleaning the accuracy would resume. For example: With a non-fouled barrel, I could dial up my Android shooter app, make the elevation and windage adjustments, and I was consistently/consecutively breaking clay pigeons in a gravel pit from 690 yards.

    Now, here's where the change comes into play. I purchased a Shilen 6.5x284 Norma barrel for a switchbarrel project and had the gunsmith anchor the barrel nuts on the 22.250 and 6.5 barrels so both could be changed and maintaining proper headspacing. So, today, with a clean barrel, I went out to re-sight in my 22.250 (for coyotes donchaknow) and... to my dismay, my one-ragged-hole gun is now shooting all over the place (between 1" and 4" groups at 200 shooting prone, i.e., consistently inconsistent). (FYI: The smith said he set the 22 barrel back just a scoche before pinning the barrel nut because he wasn't comfortable with the current headspace.)

    So, my mind is racing... why SUCH a difference? Scope, action, barrel: All tight. Load: Same as before. Barrel, same, but set back a bit. I suppose the barrel harmonics, etc. could have just been in the zone and now the system is "out of tune". All I can figure is I'm going to need to head to my local range when I return from the inlaws so I can test again from the bench because today I was behind a shelterbelt of trees to stay out of the 20mph wind.

    In the meantime, I'd like to hear your input. Thanks in advance.