Im kinda stuck on this one. I bought two new stainless steel 35 whelen encore barrels from Thompson Center both are 28''. I have shot both the rem core lok 200 gr and the Hornady superformance 200 gr and cannot get the rifles sighted in. They will shoot descent the first two or three shots then after that they are all over the place. I usually run a bore snake through them ever so often. Is there something that I am doing wrong or has anyone else run into this problem. I have had some tell me that I should get a larger hinge pin to take the slack out of the barrel where it mounts to the frame.