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View Full Version : How long to wait between shots for barrel cooling?


Cowboy_mo
January 3, 2011, 12:21 PM
When you are shooting to test "best groups" how long do you wait between shots to ensure the barrel isn't heating too much?

Yes, I know I can feel the barrel but yesterday when it was 30 degrees, I never did notice any barrel heating, yet the first 2 shots would almost always touch and the 3rd would always be the farthest off.

GeauxTide
January 3, 2011, 12:26 PM
I usually wait a minute.

4runnerman
January 3, 2011, 12:46 PM
I was always told when 2 grouop and one wont,,keep looking for another bullet or load. You have not found your best load yet. I don't think this has any thing to do with barrel being warm at all.

Qtiphky
January 3, 2011, 03:50 PM
I friend of mine, who was a sniper in the military, said that when they would sight their guns in, they would typically wait almost 20 minutes between shots to ensure a "cold bore" shot as that is what they will be shooting with in the field. Don't know if this is true or not, but it seems to make sense to me. Also, they would sight there guns in down south where the ambient temp. is much higher than around here and that is why they would wait so long.

Yesterday I shot four different guns with four different loads. The ambient temp was 18 and I shot one gun/one shot at a target, then a different gun at a different target (1 shot), and so forth until I had shot all four guns. By the time I got back to gun number 1, it was definitely real cold to the touch and I had some of the best groupings I have shot. I shot a 308, 204, 300 WSM and 22/250 in round robin fashion. Worked for me.

ndking1126
January 3, 2011, 04:30 PM
In the summer with ambient temps of 75 or higher, I would typically wait 5-7 minutes. Shooting .30-06 when it was around 90 or higher, I found my sporter barrel was hot after one shot. I'm not sure it really cooled back down until it was in the air conditioned car :)

30-40* weather, I like to wait about 3 minutes. I also believe the caliber has something to do with it. Less burning powder per shot requires less cool-down time.

My rifle does the same thing with 2 shots touching and 1 farther off for a typical group. It does it with 168 SMK Federal GMM and Remington 180 Corelocks PSP. The 168 shoots awesome out of the rifle, the PSPs shoot good enough to hunt with, but they both do it. Virgil King, builder of the famed Houston Warehouse back in late 70s/early 80s said he noticed he could call shots because barrels will shoot patterns based on cleanliness. For example, First shot right on, second shot high right, third shot low right. Clean, and then the same POI would show up in that order. Just a thought, I can't confirm or deny if it's true or not.

700sage
January 3, 2011, 05:03 PM
"When you are shooting to test "best groups" how long do you wait between shots to ensure the barrel isn't heating too much?"

Why are you testing "best groups"? What is the purpose of the round being developed?

For example for a hunting load you want a load that will group good even though you've alread shot twice in a few seconds. (Good being around 1 MOA) Hunters are also concerned about velocity and energy. They will sometimes take a slightly less accurate load in lieu of a load that generates more velocity and energy. It's a balancing act that hunters perform with their selection of ammo and gun.

For target shooting you generally have enough time between shots to let the barrel cool for a bit then shoot again. Target shooters are looking for best accuracy for shots placed about a minute apart. Accuracy is all they care about. The only concern with velocity is that the bullet doesn't go from supersonic to subsonic speeds at the ranges they intend to shoot. The transition will cause turbulance in the flight of the bullet and decrease accuracy.

As for a sniper situation, you want to know what the gun is doing on a shot with ambient temperature for one round. To them the only shot that matters is the fist shot because it's generally the only shot. They will let the barrel cool to the air temperature. They will also keep a log of the gun and test the gun at various air temperatures and record the deviations at different temps. This way they can shoot at any temperature and almost ensure a connection from a cold bore at any range within the guns capability.

ndking1126
January 3, 2011, 05:29 PM
Why are you testing "best groups"? What is the purpose of the round being developed?

I can't speak for the OP, but I know when I read his post, I immediately thought back to when I was picking a commercial hunting round for my .30-06. At the time, I was only hunting whitetail so amount of energy or velocity wasn't important to me as they all were good enough. I did however want to know which was the most accurate. Not that a bullet that would shoot 1.5 MOA groups was a much worse option than a bullet that would shoot 1.25 MOA groups for my area (200yrd shots or less), but I still wanted as much accuracy as possible.

I guess "best groups" doesn't only apply to people developing rounds, at least I think that's what you are asking.

Cowboy_mo
January 3, 2011, 09:51 PM
Yesterday, I was trying to compare 2 different types of commercial ammo. I wanted to see which brand would group the best.

When developing rounds I also want to see the same thing. I am not so interested in velocities as I am in consistency.

The rifle is a T/C Venture in .30-06 spfld. But, I have also read all kinds of data regarding barrel heating and its affect on POI. But I have never read or heard any kind of guideline on determining the time to wait for cooling.

Thanks for all your input as it is very helpful.

Zak Smith
January 3, 2011, 11:47 PM
Before the wind changes.

10mmAuto
January 4, 2011, 07:51 AM
In regards to shots fired from the cold bore compared to those not, the only sniper I know well said "shooting a guy is shooting a guy". One can only assume his point was that unless in extreme circumstances everything's about the same but this is with the M24 which has a relatively thick barrel. If you're using a light profile barrel I'd say until the thinnest part feels room temperature.

Mannlicher
January 4, 2011, 08:29 AM
while opinions vary all over the place on this subject, I always shoot at least two or three shots fairly close together, if I am testing a hunting rifle.
In the field, if you miss that first shot, you need to know where your second and possible third shot are going.

With a paper puncher, well I don't really know. I do not own any paper punchers. :D

Slamfire
January 4, 2011, 09:32 AM
I have seen people waiting 2 minutes between shots.

What I do know is that light sport weight barrels walk a lot more than heavy target barrels. I shoot heavy target barrels without regard to a cooling down period. Light weight barrels, who knows, they are all different.

okbob51
January 4, 2011, 02:14 PM
Zak Smith got it right. Benchrest shooters (who shoot the smallest groups) are less concerned with barrel heat and more concerned with wind shifts. Their guns are designed to shoot FAST....before the wind condition changes.

4runnerman
January 4, 2011, 02:20 PM
I bench shoot and i still wait inbetween shots. I try pick good days to shoot,but range is 25 miles aweay so it is what it is when i get there. One shot about every 2 or 3 minutes.:)