Figured it out....

[7x57 Shooter]

My Mod 70 300 Win mag was stringing bullets, I took the bi-pod off and it would close the groups. I would get two cold shots into an inch and then it would start stringing shots.
I checked when I got home, I found that when the bi-pod was attached the wood under the bi-pod touched the barrel making the rifle shoot differently. There was a lot of wood that was touching barrel, I bedded it after reaming the barrel channel.
This method ahs always worked for me, I usually shoot Remington's, I am hoping for the same good results with the Mod 70.

 

[Shynloco]

My Mod 70 300 Win mag was stringing bullets, I took the bi-pod off and it would close the groups. I would get two cold shots into an inch and then it would start stringing shots.
I checked when I got home, I found that when the bi-pod was attached the wood under the bi-pod touched the barrel making the rifle shoot differently. There was a lot of wood that was touching barrel, I bedded it after reaming the barrel channel.
This method ahs always worked for me, I usually shoot Remington's, I am hoping for the same good results with the Mod 70.

Great you got your issue figured out. It's a valuable lesson you've learned that anytime you change or add anything to do with the stock, there is a good likelihood that you will get different results. That's why it's a good idea to take a dollar bill (sliding it between the stock and barrel) after or changing anything to check the clearance between your stock and barrel. I've found bipods or anything screwed into the stock/strap mounts CAN cause you much grief when not checking for any slight contact to the barrel which definitely alters accuracy due to the change in harmonics. Good luck with that Mod 70 that should make you a happy camper. Great shootin rifle for sure.

Alex