I've been scratching my head over this for a few years, so if you have a theory, I'd love to hear it.
1994 Colt Match Target; stock Colt 20" barrel, National Match - style freefloat tube/handguards; 1/7 twist; upgraded A2-style sights with 1/4-1/4 clicks. Shooting off sandbags, zeroed in at my club's indoor 100-yard range.
This rifle is sighted in with my favourite handloads using 69-gr SMKs and 68-gr Hornady BTHPs, both of these loads print in exactly the same location. Velocity is about 2,750 fps.
However, when shooting any 55-gr FMJs, whether it is my reloads with Hornady FMJBT-WC bulk bullets, or surplus Lake City or IMI ammo, the groups print 3.5 inches left and 3.5 inches low at 100 yards.
I suppose another way to look at this is to say that the 69-gr bullets print high and right...
This difference in POI has been observed at ranges of 100, 200, 300, and 550 yards.
What's causing such a dramatic shift in POI?
1994 Colt Match Target; stock Colt 20" barrel, National Match - style freefloat tube/handguards; 1/7 twist; upgraded A2-style sights with 1/4-1/4 clicks. Shooting off sandbags, zeroed in at my club's indoor 100-yard range.
This rifle is sighted in with my favourite handloads using 69-gr SMKs and 68-gr Hornady BTHPs, both of these loads print in exactly the same location. Velocity is about 2,750 fps.
However, when shooting any 55-gr FMJs, whether it is my reloads with Hornady FMJBT-WC bulk bullets, or surplus Lake City or IMI ammo, the groups print 3.5 inches left and 3.5 inches low at 100 yards.
I suppose another way to look at this is to say that the 69-gr bullets print high and right...
This difference in POI has been observed at ranges of 100, 200, 300, and 550 yards.
What's causing such a dramatic shift in POI?
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