lever gun shooting... weird...

[milktree]

I've got this marlin lever gun in .38/.357, and it shoots high... but only with .38s. Same gun, same distance, same target, no change to the sights, and the .38s shoot about 5" higher at 25Y than .357s.

This makes no sense to me.

The only thing I can think of (and I'm making stuff up here because even this theory doesn't make much sense to me) is that because the .38s are moving slower in the barrel, the gun has more time to recoil, pushing the muzzle upwards, but the .357s are so fast they leave the barrel before the gun can move much.

That doesn't make sense because the gun barely moves with the .38s (they're mild, 125gr at about 650fps) and the .357s are closer to 1,300 fps and 158 grain bullets, so the gun moves a lot more. Not only that, but every revolver I've shot shoots higher with faster ammo, excactly the opposite of this behavior.

Am I missing some piece of theory or information that would make this make sense?

 

[bfm]

Short answer is even different wieghts of the same ammo from the same company can print really differently. As for why it is higher, it may be closer to the apex of its arc than the .357. The magnum might still have a lot of rise left in it farther out.

 

[Zappa]

I've got this marlin lever gun in .38/.357, and it shoots high... but only with .38s. Same gun, same distance, same target, no change to the sights, and the .38s shoot about 5" higher at 25Y than .357s.

This makes no sense to me.

The only thing I can think of (and I'm making stuff up here because even this theory doesn't make much sense to me) is that because the .38s are moving slower in the barrel, the gun has more time to recoil, pushing the muzzle upwards, but the .357s are so fast they leave the barrel before the gun can move much.

That doesn't make sense because the gun barely moves with the .38s (they're mild, 125gr at about 650fps) and the .357s are closer to 1,300 fps and 158 grain bullets, so the gun moves a lot more. Not only that, but every revolver I've shot shoots higher with faster ammo, excactly the opposite of this behavior.

Am I missing some piece of theory or information that would make this make sense?

You nailed it right there.
The muzzle has more time to rise because the bullet is slower and spends twice as long getting down the barrel..
However, if you stretch out the distance to say 75-100 yards, you'll see less of a variation in the points of impact because the slower bullet reaches the peak of it's trajectory arc at about 25 yards from the muzzle, and drops off quicker than the faster, flatter shooting bullet.

 

[milktree]

You nailed it right there.
The muzzle has more time to rise because the bullet is slower and spends twice as long getting down the barrel..
However, if you stretch out the distance to say 75-100 yards, you'll see less of a variation in the points of impact because the slower bullet reaches the peak of it's trajectory arc at about 25 yards from the muzzle, and drops off quicker than the faster, flatter shooting bullet.

Why doesn't the same thing happen with handguns? In fact, the opposite happens. Slower bullet, lower impact.

 

[Zappa]

Why doesn't the same thing happen with handguns? In fact, the opposite happens. Slower bullet, lower impact.

Shorter barrel length.
The time differential between the two different speed bullets leaving the barrel is much shorter than in a rifle length barrel.
Also, handguns are lighter in weight and react quicker and more violently to the recoil.
However, I've shot heavy 8" barreled .357's that have reacted the same way as your rifle, where the slower .38's hit higher than the faster .357's. But you also typically shoot handguns at closer distances than you do rifles.

 

[TonyDedo]

Another idea, could also be that your .38s are shooting fine, and your .357s are shooting low. Could be flinching/snatching the trigger with the higher recoiling round...

 

[milktree]

Another idea, could also be that your .38s are shooting fine, and your .357s are shooting low. Could be flinching/snatching the trigger with the higher recoiling round...

Seems unlikely, I'm a (half) decent highpower shooter, which doesn't reward flinching, and the groups are reasonably tight. I did a bunch of testing off a rest, which should fix that.