"keyhole"ing is usually from not enough spin stabilization and a 1/7 on a 55gr would be sort of over stabilized or over spun.
The only key holing I have ever seen is from a 1/12 barrel that was cut down to 8.5"....and that particular piece seemed to throw them sideways regardless of gr.... This barrel was on a well worn 53 sear host and could almost qualify as a smoothbore too.
It will not make the bullet key hole unless you have a problem with the barrel. I shoot 55 grain bullets through 1/7 twist barrels all the time with no problems. I have a 7 inch barrel SBR AR that will shoot under a one inch group at 50 yards with 55 grain bullets.
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