Point of impact change question

[Dan B]

I have a question that has bothered me for a while:
In my REM 700 in .243 Winchester, going from 70 grain varmint type bullets (Nosler and Bergers) to various 85 to 95 grain hunting type bullets (Hornady, Nosler, Barnes) I have an 8+ inch diagonal change in the point of impact at 100 yards, the heavier bullets impact about 6 inches to the left and 6 inches lower then the lighter ones, group sizes are good, generally less than in inch. The stock is synthetic with a metal block (HS) and the action has been bedded, the barrel is free floated.

I haven't experienced this in other rifles; usually the change in bullet weight gives a vertical change in impact but nowhere such a large lateral change.
Is this indicative of anything or normal?

Thanks,
Dan

 

[Lefty Dick]

Harmonics baby.

Not all barrels will exhibit the same harmonics.

Not all barrels are or can be built the same.

 

[stubblejumper]

It's not at all unusual to see the point of impact move horizontally, as well as vertically.

 

[pats]

Barrel twist , your heaver bullets might be walking a little with the twist rate . I noticed this in my 308 rifle when I started to reload for it and was trying different bullets and generally learning different stuff .
Your twist rate is there to stabilize your bullet , but as different bullets are produced , something might change ,as some one mentioned , harmonics .

 

[H4831]

I can tell you right now that your rifle is very poorly bedded.
A hunting weight rifle that has the action well bedded and a fair bit of pressure on the front of the barrel to minimize barrel vibrations/harmonics, will shoot all weights of bullets to very close to the same point of impact at 100 yards.
A good example of this in a new rifle is the Marlin XS7, or some such thing, in 243 Winchester, which i recently bought.
I was quite happy to find out there was no change of impact from the very first shot through the fifth, when the barrel was too hot to hang onto.
Next, I found that 70, 75, 85 and even 100 grain bullets all went into virtually the same group. Certainly hunting accuracy with any load.
I was impressed. The rifle is stated to have pillar bedding, so I took the stock off to see what pillar bedding looked like. The only difference I could see between it and any other plastic stock, was a nice saddle at the front of the stock, which put a fair bit of pressure on the barrel when everything was tight.
This is the way I have bedded all my bolt action rifles, for as long as I can remember.

 

[stubblejumper]

I can tell you right now that your rifle is very poorly bedded.
A hunting weight rifle that has the action well bedded and a fair bit of pressure on the front of the barrel to minimize barrel vibrations/harmonics, will shoot all weights of bullets to very close to the same point of impact at 100 yards.

Obviously , you missed the part about the barrel being free floated.

The stock is synthetic with a metal block (HS) and the action has been bedded, the barrel is free floated.

Contrary to what you may choose to believe, many people prefer a free floated barrel, and find the point of impact to be more consistent in changing conditions than a barrel that has a pressure pad pushing up on it.

To the OP, if the gun shoots good groups, with no stringing, I wouldn't worry about the bedding.