Bit of a mystery?

[Miseryguts]

Hi - Henry Lever action rifle in 44Magnum with Rudolph 4-16x42 scope atop

240gn copper plated RNFP bullet over 6.8gn Unique exiting the muzzle at 990fps, rig zeroed at 50m

240gn copper plated RNFP bullet over 19.5gn N1110 exiting muzzle at 1500fps - rig unchanged but now POI is 8MoA below POA at the same 50m.

Now  in my simplicity I imagined that the POI of the second bullet should be above POA?

Or am I being stupid??

M (puzzled in sunny Monmouthshire)

[Catch-22]

I may be the stupid one but isn't the faster bullet just getting to the target more quickly, so has a flatter trajectory...thus impacting BELOW the slower round?!?? 

[gunner]

Is it to do with the way gun recoilles? With faster load muzzle doesn't have time to rise fully when bullet exists muzzle ? Quite strange tho .

[Miseryguts]

13 hours ago, Catch-22 said:

I may be the stupid one but isn't the faster bullet just getting to the target more quickly, so has a flatter trajectory...thus impacting BELOW the slower round?!?? 

The way I look at is:

Rig is zeroed with the slow bullet, so the axis of the parrel is pointing in such a direction that the loop of the bullet trajectory  means that it lands on the POA at 50m. Light travels in a straight line, so the scope axis is pointing straight at the target whilst the rifle axis is pointing slightly up so that the loop of the trajectory falls to the POA at 50m.

Insert the faster bullet, then with the above scenario the bullet will impact above the POA

13 hours ago, gunner said:

Is it to do with the way gun recoilles? With faster load muzzle doesn't have time to rise fully when bullet exists muzzle ? Quite strange tho .

I like that better, but 8 moa is  lot, and this is very repeatable, and I get 1 to 1.25 moa 10 shot groups with both bulles, only not at the same POI!!

[simonl]

Have a google of barrel harmonics.

Your barrel wobbles all over the place as the bullet travels down it. When it exits there's no saying which way it'll be pointing.