Browning A-Bolt 7mm rem mag
w/Leupold Vari-x III 4.5 X 14
w/Federal Premium Nosler Balistic tip 150gr

Now, to the question.
When sighting in, how long do you think I should wait between shots? I am concerned that warm/hot barrel temps could effect accuracy, compared to cold barrel. Is it enough to be concerned?
Thanks

Shoot a 3 shot string, one right after the other, just like you would in a hunting situation, then check your groups. Let the barrel cool completely, 10-15 min, after that before shooting another string. You aren't going to let it cool in the field between shots.

There are a couple issues. HuntKY hit on one regarding finding out where three quick shots would go in a hunting situation (i.e., the second and third ones aren't going to be through a cold barrel). However, I think the bigger issue is whether your gun puts the first shot into the same place every time from a cold barrel. If the first shot from a cold barrel goes into the same place every time, I personally would pay more attention to sighting in that first shot than centering a group on the middle of the target. Obviously you need to also know where the second and third shots would land under hunting conditions, but the first shot should be the priority in this situation.

To sight in for your first shot, then obviously you would want to let the barrel cool before trying another shot that would cause you to adjust your scope. The amount of time you need to wait to get a cool ("cold") barrel depends on the ambient temperature, wind speed, whether the barrel is in sunlight, etc. The most sure way of shooting a cold barrel is to use the first shot of a range session as what you use to fine tune your scope settings. Absent the luxury of multiple range sessions, I would let the barrel cool until it felt about the same as the air temperature and then let it sit a few more minutes; or if you want to be more exacting, because the temperature of the barrel's outer surface cools faster than the inside of the barrel, I'm sure you could use a thermometer inside the barrel (I would put it in the chamber end) to see when the temperature returned to the ambient temperature.

There are various techniques that some people use for cooling barrels in hot weather, but since I haven't used them, I won't recommend any of them.

It all depends...

It depends on what you are trying to do. Are you trying to characterize your rifle under hunting conditions? Or are you trying to sight it in as accurately as possible?

Timing your shots may not be your best choice. In moderate temperatures, the barrel cools a LOT faster than it does on a hot day. The inside of your wrist may be a better indicator than your watch.

I'd be concerned with the "hottest" loads on the hottest day with a Chrony before anything else registered. At least if I was seeking the highest speeds with that accuracy....

I appreciate all your responses.

The point of my sighting in is for hunting accuracy. I agree the first shot matters the most, as in an ideal world I would get away with saying I have only needed one shot on every kill. LOL

So, I am going to incorporate your suggestions. First, I'll make the first shot on paper and if I am satisfied there was no error in my shot, then adjust the scope to match the point of impact. Then, while the barrel is still warm, fire off 2 or 3 more shots, noting where each bullet hits the paper. If it's not too far off, I think I would be better off stopping right there. Another trip to the range on another day will verify if the adjustment was correct. Any thoughts?

What brought this up was a day at the range last summer where I fired over 200 rounds trying to sight it in at 200 yards. I am not that bad of a shooter, so I am thinking I was chasing a moving point of impact due to the variance in temps in the barrel. While a full day at the range can be fun, over $500 in bullets is not.

Kutter,

Living in the south you need to be careful shooting alot of rounds out of any magnum during the summer heat.

I have a 7 WSM and in Aug./July Temps I could shoot a 3 round group of "1 or so. It always was the 3rd shot that opened the group up.

When I would wait 10 min. or so, I could lay that 3rd one right on top of the other 2, decreasing the group size to the 4.'s & .5's.

If you want a cold bore zero, shoot your first shot carefully, make your adjustments and wait 20 min. Take the bolt out and lean the gun upright to let the barrel cool.

Fire the next shot, make any adjustments and let the Bbl. cool again for 20 min.

Save your last target after you have it where you want it. Bring this target back to your next range session and shoot it with your first cold bore shot to make sure the POI is the same.

I always make sure I have cleaned my barrel on the previous trip and fired at least 2 rounds thru it at the end of the range session so next time I go to shoot, I won't be working with a clean cold bore, which can give you different POI's. I always have 2 foulers thru there before doing any serious shooting or hunting.

Hope this helps,

JM.

Thank you, that's very good advice.


(Perhaps you are more right than me on the name change too. Klutter, I love it and it fits me too. LOL)

My apologies buddy. I'll correct that.

Best,

JM.

Amen.
My technique exactly.
Just used it two days ago shooting one of my Duces; three shots one right after the other, then a 15 minute break. And midway betweeen barrel cleanings, I shot one of the best groups I've shot with an old Rem 722, a .280 at 100 yards.

Kutter-I keep a probe thermometer in my kit when I go to the range. You know the kind that restaurants use.

If I really want to test out loads and am worried about heat here's what I do.

I stand the gun in the rack at the range and I stick the thermometer down the tube (mzl end). This will give me a good idea as to what the internal temp of the tube is. Say it comes out @ 70 or whatever (and this is b4 shooting it).

I shoot my string (and don't forget to take the darn thing out first....), and then after my string I stand the rifle back in the rack and insert the probe thermometer again. The temp will be higher, I then let it sit in the rack till the temp comes back down to where it was b4 I started my shooting. Which in this case was 70.

Hope this helps you out, it's worked well for me for a couple of decades now.

Best of luck to ya

Dober

When at the range I am looking for consistency, so before making another shot I look down the top of the barrel, when the heat waves or mirage stop coming off of the barrel I fire my next shot.
This is generally about 3 minutes between shots.

Gee, Mark, that's pretty scientific! Wish I was a rich real estate guy and could afford thermometers to stick in the muzzles of my $1000 rifles....

I generally just wait until the barrel can be comfortably held in my hand. This is speeded up in summer by either pouring cold water on the barrel (which doesn't hurt a thing) or draping a wet towel over the barrel with the rifle in the shade.

Standing the rig VERTICAL,in shade, to cool, with the bolt / breech open is excellent advice.

GTC

At my shooting partner's home, we are near enough the house that we have a fan running on the sun porch. We alternate shooting strings and the rifle not shooting gets the bolt pulled and sits on the table with the fan blowing through it - works well. I also have started blowing a breath of air into the chamber between shots. It sounds kind of dumb, but the amout of smoke/gas that it pushes out of the muzzle makes me think that it isn't a bad idea. At the range my son and I belong to, we sometimes take along a small fan and run it off the lighter. Other times we take along a cooler and keep a rag wet in it. The resting rifle gets the rag laid along the length of its barrel.

Don't mess up your follow through, but after the shot getting the hot brass out of the chamber as quickly as possible helps.

Something I thought about. Others might have, too, but I have never heard anything it, but I read on here the other day about barrel fitting.

One of the better gunsmiths (Greydog) said that he allows .002 for compression when he installs a barrel.

When you shoot several rounds and the barrel gets hot, the shank of the barrel expands, lengthwise and in diameter, making the barrel shoulder tighter against the action, possibly enough to slightly warp the action, or at least the front receiver ring. Or, the expansion could also put more than the .002" compression on the receiver and barrel.

This could result in either a short lengthening of the chamber or maybe even shorten the chamber, if the barrel shank expands against the front of the action or against the ring the locking lugs fit into inside the action.

Does anyone else have any opinions about this? I am not talking about installing the barrel with no compression, because the barrel needs to be tight.

Shooting in bright sunlight on a hot day, as opposed to a cool day, could also cause he barrel and action to expand, and the barrel to lengthen, affecting accuracy.

Mark,

Are U bird turding the troops? Again??

Huh?

Dober

BS'ing the peeps, I think he means?

Nope, not at all its about as straight forward as it gets...

Dober

I've used Mark's method... a restaurant type probe thermometer is a whopping $7 purchase. I've used that or my old Taylor glass tube thermometer... either work.

Mule Deer, I've dumped water down my barrels to cool them on hot days.

Question: do you patch it back out again, just to be safe...? From overpressure from the water in the tube, I mean.

The human hand makes a wonderful thermometer, about 120-130 deg becomes uncomfortable.

I used to bring my infrared RayTek temp gun to the range but found my hand works just fine.

MtnHtr

Mtn, couldn't agree more and that's mostly what I do, but Mark's method is also very solid and simple... here's a few pics to illustrate for the literary impaired:

Jeff,

I tried water down the bore but found pouring it on the outside worked just as well, and didn't complicate things.

123 etc.,
The .002 compression figure is typical. If measurement indicates a head space figure (Hold it right here for a second. If anyone chimes in about how headspace is a measurement to the datum line of the cartridge, I swear I will find you and slap you upside the head)of say, .750, the gunsmith will run the reamer in to give a figure of .748 since the shoulder will compress about .002". While temperature does alter dimensions, heat transfer to the receiver will likely keep torque andtherefor, compression of the shoulder, reasonably constant.
In other words; a person could lie awake nights wondering about this but I think there many other things more worthy of insomnia than this.
Some benchrest competitors (mostly hunter class where barrelsare lighter and cartridges larger than in the varmint classes) were running water through their barrels between targets and claimed better scores as result. Never tried it myself.
Stories are told of buffalo hunters urinating through their barrels to loosen fouling and cool the barrel. It is assumed a professional hunter would posess a steady aim and so be able to apply the liquid to proper location. I don't think I need to point out the potential hazards should a bolt close inadvertently. Best to remove that bolt. And use a good rust preventitive between shooting sessions. I have no first hand experience with this as a means of cooling a barrel or loosening fouling.
I do have some solid second hand experience with this method as a means of warming up a rifle, however. It seems our hunter was struggling through hip-deep snow on a cold day on Vancouver Island. Snow had packed into the action of his Browning bolt action rifle and frozen to where cycling the bolt was impossible. Having no other source of heat handy, he decided his best option was to urinate on the rifle to melt away the ice. Apparently, this was successful.
My involvment came about the following fall when the rifle was brought into the shop because the trigger wasn't working. Now, I have had rifles come in which stood in the corner of the corral over the winter. I had one rifle brought in which had been lost and left leaning against a tree for a year (a bit of a funny story, that one). I worked on a 22 which had spent it's life leaned up in the corner in an abbatoir. But,I HAVE NEVER SEEN A RIFLE AS THOROUGHLY RUSTED AS THIS. When I pulled the barreled action out of the stock, at least 1/16 inch of wood came with it! The hunter gave me the explanation when I asked if the rifle had been stored near saltwater. As a professional gunsmith, I had trained myself to maintain a neutral expression through many customer dissertations but I'll confess to having some difficulty with this one! GD

greydog-

Your postings are always informative, and this one is especially so.

The buffalo hunters may have used a rifle cleaning funnel, which was a common accessory for military and sporting cartridge rifle users, from the 1860s through WWI.

I hope the owners of this image won't mind a link to an image of a funnel used by the British in WWI. I assume it was for water and other bore cleaners.

With the larger target supplied by a funnel, the problems of aiming and injury from mechanical causes are certainly decreased.

--Bob

Greydog:

I understand what you mean. What I was talking about is that the .002 compression gives the barrel a pretty tight fit on it's own. The heat, causing the metal to expand, adds even more tension, and my thoughts were that this added tension could cause warpage. You know, like you only need .002" for proper headspace, and you give it .007." That would make for a very tight fit, and heat expansion would make it even greater.

As an example, I used to have a blackpowder revolver. After shooting it, I would take it completely apart and soak it in a pan of very hot, soapy water, then I rinsed it in hot water. If I dried it off and attempted to assemble it while it was still warm, None of the parts and screws would fit until I let it cool to room temperature.

Incidently, your posts are the most informative and knowledgeable of any of the gunsmiths on here. You seem to know exactly what you are doing and how to do it, and you seem to rely on what works and doesn't work, as opposed to theory.

I have read articles in books and magazines where the authors made statements about things I had experienced and knew about. I knew right off that the author had never experienced these things first had, and had probably just copied the information from another book, written by someone who also didn't know what he was doing.

Really.

GTC