how long before barrel heat affects accuracy

[toddy]

As the title says? I am curious to know when barrel heat starts to affect accuracy and when damage begins.

Reason I ask is I have the new .270 and I sighted it in with cheapy Winchesters and recently purchased what I think is a good round for Bear. Sako hammerheads 156 gr. I was sighting the gun in last Saturday in the rain (time is limited) and the I may have only fired 9 or so rounds to zero at 70 yards but wholy crap the barrel was hot. was actually steaming as the rain would hit it. Outside temperature was maybe 8 degrees. I don't believe I could have caused any damage after 9 rounds, but I am really curious to know when is too much.

[Bluebulldog]

You'll have to shoot a lot...lot more higher velocity rounds before you'd ever come close to permanently affecting the barrel.

Typical magnum calibers, and know "hot" loads will eventually start to have an effect. But for a relatively moderate round like the .270, you're GTG for a few 1000 more. Now if you're asking how much heat affects a barrels consistency, then yes, allowing barrel to cool in between shots is optimal.

[MikePal]

. Now if you're asking how much heat affects a barrels consistency, then yes, allowing barrel to cool in between shots is optimal.

Even that is subjective to what you consider 'accuracy'....at 70yds shooting sub-moa, it would take a whack of shooting before you notice the group size growing beyond MOA, at that distance.

[Bluebulldog]

Even that is subjective to what you consider 'accuracy'....at 70yds shooting sub-moa, it would take a whack of shooting before you notice the group size growing beyond MOA, at that distance.

Very true. I think the Op gets the picture though.

[MikePal]

I wonder where this worry comes from. In the military we used to shoot belts of ammo, boxes of mags one after the other and never once was there a concern about the barrel over heating. At least not in the smaller calibers.

The only time I know there was a drill for removing an over heated barrel was with the .50 cal belt feed guns.

Barrels may be hot to the touch, but those temps are far below the temps required to affect the barrels integrity. It would have to be almost glowing red.

When I clean my ML fluted barrel I use a kettle of hot water, as I pour it down the barrel I cannot hold on the barrel bare handed. They are designed to dissipate heat quickly.

[Snowwalker]

The mirage in the scope created from the hot barrel would effect your accuracy before you hurt the barrel. For the first few hundred rounds the barrel will warm up quicker till it is broken in.
The machining marks still need to be smoothed out in the lands and grooves.

[Kilo Charlie]

3 to 4 rounds from a .270 will make the barrel hot to the touch. Typically, I will shoot 3 or 4 shots, wait ten minutes to cool, then shoot another group.

[MikePal]

3 to 4 rounds from a .270 will make the barrel hot to the touch. Typically, I will shoot 3 or 4 shots, wait ten minutes to cool, then shoot another group.

Hey KC, have you ever noticed a difference if you continue to shoot with a hot barrel....I had a guy on the range one day tell me that it did, but after awhile I saw it wasn't the 'heat' as much as shooter fatigue causing his rounds to climb.

By taking a break after 5 rounds to cool down the barrel, it also allows you to stretch out a bit before the next set.

[Bluebulldog]

I wonder where this worry comes from. In the military we used to shoot belts of ammo, boxes of mags one after the other and never once was there a concern about the barrel over heating. At least not in the smaller calibers.

The only time I know there was a drill for removing an over heated barrel was with the .50 cal belt feed guns.

Barrels may be hot to the touch, but those temps are far below the temps required to affect the barrels integrity. It would have to be almost glowing red.

.

I always found it funny. On the Machine Gunners course, you'd carry the spare barrel for the C6 with the expectation of barrel change out after every 3 or 4 belts.

.....never actually happened unless you had the course O walk by.....

[welsh]

Accuracy isn't really your leading concern with a C6.