A weighty question...

[mikerjf]

I recently read a comment by Bill Wilson regarding his preference for 185g bullets in compact 45s. Having a column of cartridges that weigh less makes it easier for the magazine spring to lift them. That got me thinking about the effect of bullet weight apart from ballistics.

When you have a fully loaded handgun, that gun is at its maximum weight… and the recoil of your first shot will be based on that weight. But on each subsequent shot the gun weighs slightly less… the bullet and powder from one cartridge have left the building. So as we fire shot after shot, the recoil increases for each shot. The final shot will have the highest recoil of the series.

We know that manufacturers regulate the sights of a handgun for a specific bullet weight. POA is set above where the bore is actually pointing, under the assumption that the shooter’s reaction to recoil will cause him to raise the bore slightly by the time the bullet leaves the barrel. Having the POA pointing above the bore at rest means that recoil raising the gun will move POI to coincide with POA.

With adjustable sights you can, of course, adjust POA relative to POI.

So since the recoil will increase with each shot as the gun gets lighter, and more recoil moves POI higher relative to POA, should you adjust your sights:

1) with the gun fully loaded, since in an encounter you will always fire that first shot, but may or may not fire the rest.

Or:

2) with the gun half loaded, so that POA/POI are the closest on average over the entire range of recoils.

What say ye?

 

[Alk8944]

It really doesn't work that way in practice. The slight difference in muzzle climb shot-to-shot will, in reality, be less than your ability to shoot groups. You can prove this, and answer your question at the same time, by firing several groups from rest. Spot each shot as it is fired and you will find there is no pattern that corresponds to number of rounds in the gun for each shot.

If there was any truth to what you propose all of your groups should show a definite and consistent vertical stringing. You will not see that to any noticeable degree. Both you and the gun would have to be able to shoot one-hole groups for there to be any noticeable round-to-round difference from this cause.

 

[armorer951]

In terms of POI, as witnessed above, the weight difference is minuscule. 185 grain vs 230 grain difference in 7 rounds would be approximately .714 ounces.

And.....if the feeding reliability of the magazine is affected by this tiny amount of weight, the magazine spring needs to be replaced.

 

[Greyman50]

One reason for a 6 O'clock Hold in bullseye shooting.

 

[Nightowl]

Interesting observation, one that I had never thought of or considered! In terms of pure physics, there may be some affect, all things being equal! But, as noted by ALK8944, in practical real world terms, it is negligible at most!

 

[CALREB]

Having an inconsistent grip will cause more vertical stringing than bullet weight or gun weight. Especially at normal handgun shooting distances 50 yards or less. IMO
I do admit there is some change of impact through some guns when the bullet weight is changed but it's not consistently high, some low, some left etc..

 

[zeke]

Semi automatic poi isn't affected nearly as much in terms of bullet weight compared to a revolver, let alone change in gun's weight as it fires through a mag.

 

[Alk8944]

One reason for a 6 O'clock Hold in bullseye shooting.

No, it is not! The reason for a 6 o'clock hold in bullseye shooting is because the bottom of the bullseye is a more precise/consistent aiming point than in the middle of the black bullseye with black sights!

Zeke, there is no more effect on revolvers than semi-autos. In fact, if there was the effect would be more noticeable with large caliber revolvers, but it isn't detectable with them either!

 

[xfarfuldog]

ALL of my rounds in GOD'S caliber are 230 grain.

 

[Krogen]

No, it is not! The reason for a 6 o'clock hold in bullseye shooting is because the bottom of the bullseye is a more precise/consistent aiming point than in the middle of the black bullseye with black sights!

Correct Alk8944. In fact some of us use a sub-six hold. Instead of trying to make the sight just kiss the bottom of the bull, we hold just a sliver below. Looking for the tiny sliver of white is better than trying to be sure your sight doesn't go higher into the bull and be hard to detect. Some would argue a sub-six is a perfect six o'clock hold.