.550" vs .600"?

[RichCoyle]

Do you experienced shooters think there would be any difference in cold bore shot with a muzzle diameter of .550" compared to a .600"?

I have an 8mm magnum with a barrel diameter of .600". The other da I fired a cold bore shot at 300 yards and then a follow up shot as though I was hunting. The "group" was 2 1/4". I'm thinking about a new 7mm magnum and using a .550" barrel. Could I expect that kind of performance with the lighter barrel in 7mm?

 

[lancetkenyon]

Going from a light sporter to a Featherweight in 7RM?

Pretty light contour for my taste.
I would prefer a #2b to #3 at least. Or a #4 CF.

Should be OK for a cold bore hunting rifle. Might start to move for the 2nd shot, probably more walking on shot #3.

 

[MagnumManiac]

Hmmmmm, I have 2 very skinny barreled rifles, one is a Kimber 8400 in 300WM that will print 2 rapid shots under 1 MoA with ease, but walk a third shot at least an inch away.
The other is my REM 700 SPS in 300RUM, it didn't walk 3 shots at all in rapid fire, all were under MoA in a clover leaf and with slow shooting it printed 10 shots into MoA @ 100 without issue while breaking in the barrel. I was very impressed with this performance from a factory barrel and factory Barnes 180g TTSX.

Normally, I would say that a skinnier barrel is more likely to walk shots as it heats up, but now I honestly think it depends on the barrel itself and not necessarily it's thickness.

What rifling profile are you thinking of doing?
I believe this also makes a difference, 4 grooves has always been the best performer for me.

Cheers.

 

[Critter Picker]

I tend to agree with MagnumManiac in #3 that walking will depend more on barrel than muzzle diameter. That being said,I still think the smaller diameter barrel is more likely to walk than a heavier one due to harmonics.