[landtoy80]

I have been loading 7.62x54R with 150g and 174g bullets. The 150g bullets are .312, .311, .308 both flat based and boat tail. All the 150g bullets hit target about the same elevation. The 174g .311" bullet is hitting 15" to 18" higher.

What is happening when the bullet hits that much higher with the same point if aim?
Is it normal to have a heavy bullet hit much higher than a lighter bullet?

I do have a bore diameter of .315". Could it be that the longer/heavier bullet has less blow by thus getting more pressure behind it?

 

[daveccarlson]

Depends a lot on the particulars of the rifle. As a rule, there is more of a recoil impulse before the heavier bullet leaves the muzzle, so sometimes that accounts for a higher POI. The heavier bullet may have a somewhat different trajectory at distance. I have some rifles that hit closer to point of aim with 182gr. bullets, while others are closer with 147gr. bullets.


Good luck! I just got a reloading set up, so I'm looking forward to starting out.

 

[wbrown]

I do know that in handguns, a lighter bullet will hit lower than a heavier one.

Case in point. In my micro compact 1911 230 gr. ammo shoots to POA whereas 185 gr. stuff will shoot MUCH lower 6-8" at 8-10 yards.

It doesn't make sense to me. Physics I reckon.

Wendell

 

[Joop]

Depends a lot on the particulars of the rifle. As a rule, there is more of a recoil impulse before the heavier bullet leaves the muzzle, so sometimes that accounts for a higher POI. The heavier bullet may have a somewhat different trajectory at distance. I have some rifles that hit closer to point of aim with 182gr. bullets, while others are closer with 147gr. bullets.


Good luck! I just got a reloading set up, so I'm looking forward to starting out.

+1

Pretty much exactly what I was going to post, but Dave beat me to it.

Barrel harmonics can play a part, as well. If you shim/wrap barrels, you'll start to see a lot of swings in POI, even with the same load. I've seen a drop/rise of 6-8" at 100 yards, just from adding a 1 inch square piece of card stock at the right spot in the handguard or stock. But, yes, the heavies almost always print higher for me.

John