.220 Swift came out in 1935. Below is my recently rebarreled Swift on my original 1994 Winchester M70 HV. I burned out the original Schneider barrel and played around with a 13 twist Broughton in 28 inch length but did not get the velocity that the original 26" tube delivered. So I ordered up a Brux 14 twist HV profile, had it frozen by Kathy at Cryo-Plus and with a new reamer from JGS and 28 inch finished length have achieved my sought after speed of 4,050 with H414 and my favorite 55 grain Nosler BT's as original barrel delivered. This is breaking in the barrel and have yet to play with seating depth. 10 rounds for break in and no copper and very smooth. Chucks beware!
Frank


Frank


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