Mine was a 14 twist as well. In my particular rifle the magic happened with 38 grains 4064 at 3800 FPS.Question; was your .220 Swift twist 1-14" ? I never used a .220 Swift in 1-14" but, I do have a Weatherby .224 Wby Mag with a 1-14" twist and it won't shoot anything heavier than a 52gr and love flat base bullets. What it really shot into one hole in their old Barnes 50gr VLC "blue coated" bullet, which is also a flat base, I have no idea why Barnes stop making them, I bought deep back then and have enough to last a lifetime for as much as I shot it. View attachment 228194
Yes, the .220 Swift can be magical, my last one was a 1-12 twist, it loved the 55gr BT and 60gr HP flat base varmints... I have a friend who has an early Per 64 Win in .220 Swift for sale, condition is pretty much minty, it has a 1-14 twist and shot very little... I should buy it, but at this point in my life, a new shooter would most likely mean a new wife as well, The only thing at the time that would come close or besting my .220 Swift in some cases was my Mod 700 .22-250 AI 40 degree.Mine was a 14 twist as well. In my particular rifle the magic happened with 38 grains 4064 at 3800 FPS.
Not quite sure how you got 4000fps since Nosler 2023 lists 3665fps with their max load of 37 grains.The .220 Swift has been dear to my heart for over 50 years. Over that time I've found "the load" that worked for me in near every .220 Swift I've shot it in. It started with Nosler book #3 page 131... I might mention at this point; I have all the Nosler reloading books as references and this load is scaled back too (37.0gr) after book #3 and doesn't show up before #3 in #1 or #2 I have no idea why (perhaps powder)(liability) because some folks tried to push it, it is safe as it stands in book #3 in all the rifles I fired it in, but... I digress; the load is a Nosler 55gr Ballistic Tip, CCI BR2 primer, Winchester brass, the powder is RL-15 (39.0gr) "you have to weigh out each charge; don't throw charges with powder thrower, the book shows velocity at 4050 fps, on my chronograph, Oehler 35P 3 sky screen fired from a Remington M700 26" barrel it was a consistent 4000 fps with their 55gr BT with 1/2 moa and better with five-shot groups at 100 yards, on Yote's it's a meat ax "way" out there. I did shoot a few Deer with the .220 Swift and that's another story,View attachment 223201 another bullet & load. Cheers.
I don't have my old Sierra manual here, but looked up a load info for it. Sierra 55gr, Rem 9 1/2, IMR 4064, 39gr @ 3900fps, and Nosler 55gr BT CCI BR2. RL 15, 37grs, @4000fps.Not quite sure how you got 4000fps since Nosler 2023 lists 3665fps with their max load of 37 grains.
Well, if you go back into Nosler books you'll see a load of RL-15 {39.0grs} showing 4050 fps... that would be Nosler manual #3 page 131... my particular rifle was always hovering in the 4000 fps with SD's up and down a little, and I might add crazy accurate with 1/2 moa's the norm.Not quite sure how you got 4000fps since Nosler 2023 lists 3665fps with their max load of 37 grains.