Explain difference in barrel heat....

Aqualife · December 30, 2020, 09:15 PM

30 years ago or so I bought a Winchester 70 264 Win mag with dreams of hunting out west. I’d take it to the range with a box of 140 Remington core-lokt. The barrel would be extremely hot after firing 2 rounds, could never trust the 3rd shot. After waiting between shots I got it zeroed at 200 yds with in a 3” group.

This last year I finally got to take my trip out west for Antelope. I decided to shoot Nosler 100’s. The barrel doesn’t get nearly as hot. I can shoot 5 shot groups with out any issues.

Anyone have any idea why this is the case? More Pressure with the 140?

Shadow9mm · December 31, 2020, 06:47 PM

If I had to guess, probably the powder used. Some can be "hotter" than others

It could also be the outside temp. Colder temps mean the barrel cools faster.

.264 Mag has a MAX psi of 64,000 psi, so regardless of powder it should not have been over that, although it could have been less.

RC20 · January 2, 2021, 04:26 PM

Bullet length.

Shadow9mm · January 2, 2021, 07:26 PM

Quote:

Originally Posted by RC20

Bullet length.

true, a longer bearing surface would create more friction/heat

jrothWA · January 4, 2021, 10:54 AM

Have a M70 First Series post-64, in 7mmMag.
Throat is burned out, long seating the 160 gr bullet out by 0.125" just to hold a paper plate @ 100yds. Presently using 4064 powder to reload as a "7x57" Mauser round. MI whitetails don't seem slighted when shot.

Just eh magnum loads after five shoot the group when outside the black of a 50 yard pistol target, let the rifle sit with muzzle up and bolt open to get a "chimney effect" to cool down,

Bought replacement barrel that seems to have a better throat, will know shortly.

Aqualife · January 4, 2021, 09:05 PM

So bullet length sounds like as good of a reason as any. In addition the 100’s are moving faster so less time in the barrel, less transfer of heat.

Guess it all adds up.

Thanks everyone.

jrothWA · January 11, 2021, 11:00 AM

Slower heavy bullets means more heat rise pushing the heavy bullet.

jmr40 · January 11, 2021, 02:39 PM

Quote:

Bullet length.

Quote:

Slower heavy bullets means more heat rise pushing the heavy bullet.

This certainly seems logical, and I'm not disagreeing. I'm just asking, is this just a guess based on logic, or has anyone seen any documentation to back this up.

December 30, 2020, 09:15 PM	#1
Aqualife Member Join Date: June 2, 2018 Posts: 18	Explain difference in barrel heat.... 30 years ago or so I bought a Winchester 70 264 Win mag with dreams of hunting out west. I’d take it to the range with a box of 140 Remington core-lokt. The barrel would be extremely hot after firing 2 rounds, could never trust the 3rd shot. After waiting between shots I got it zeroed at 200 yds with in a 3” group. This last year I finally got to take my trip out west for Antelope. I decided to shoot Nosler 100’s. The barrel doesn’t get nearly as hot. I can shoot 5 shot groups with out any issues. Anyone have any idea why this is the case? More Pressure with the 140?

December 31, 2020, 06:47 PM	#2
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 1,067	If I had to guess, probably the powder used. Some can be "hotter" than others It could also be the outside temp. Colder temps mean the barrel cools faster. .264 Mag has a MAX psi of 64,000 psi, so regardless of powder it should not have been over that, although it could have been less. __________________ I don't believe in "range fodder" that is why I reload.

January 2, 2021, 04:26 PM	#3
RC20 Senior Member Join Date: April 10, 2008 Location: Alaska Posts: 6,512	Bullet length. __________________ Science and Facts are True whether you believe it or not

January 4, 2021, 10:54 AM	#5
jrothWA Senior Member Join Date: November 11, 2006 Posts: 2,439	A lots of powder burning and small volume of barrel steel.. Have a M70 First Series post-64, in 7mmMag. Throat is burned out, long seating the 160 gr bullet out by 0.125" just to hold a paper plate @ 100yds. Presently using 4064 powder to reload as a "7x57" Mauser round. MI whitetails don't seem slighted when shot. Just eh magnum loads after five shoot the group when outside the black of a 50 yard pistol target, let the rifle sit with muzzle up and bolt open to get a "chimney effect" to cool down, Bought replacement barrel that seems to have a better throat, will know shortly.

January 11, 2021, 11:00 AM	#7
jrothWA Senior Member Join Date: November 11, 2006 Posts: 2,439	Lighter bullet is higher velocity and more FRICTION. Slower heavy bullets means more heat rise pushing the heavy bullet.

January 4, 2021, 09:05 PM	#6
Aqualife Member Join Date: June 2, 2018 Posts: 18	So bullet length sounds like as good of a reason as any. In addition the 100’s are moving faster so less time in the barrel, less transfer of heat. Guess it all adds up. Thanks everyone.

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