[Blackbarry]

It's a tenant of the bench shooters religious beliefs that a hot barrel causes accuracy to decline. OK, I'll buy that. I have no experience here but it must have something to do with chamber/barrel dimensional expansion and a constant diameter bullet. But how hot is too hot? How am I supposed to gauge when to let it cool and to what point before I resume firing for group when determining the most accurate ammo for my gun (336 Texan .30-.30, 20")? The risk is a poor group from ammo that might be an excellent performer under "cool" conditions. Need informed opinions here..... :hmmmm:

 

[graymustang]

I just simply wait one minute between shots, when trying for groups. If it is a sunny hot day and you are not shaded the barrel is going to be hot without even shooting, to hot, is when barrel is almost to hot to hold onto.

Hunting zero's are always done from a cold fouled barrel, some rifles can be very sensitive, and a few minutes between shoots is a good idea here.

Switching make of bullet, different brands have slightly different jacket metals and/or powders.
When switching loads, fire two rounds off target to season the bore with that jacket material and load residue, then shot group. Sometimes, if this is forgotten the first round and possibly second round will be a flyer relative to the rest of the group, causing you to think the load is bad, when in fact it could be very good .

 

[Rodfac]

I pretty much agree with the above well thought out post. But here are a cpl add'l thoughts. I use 5 shot gps to determine a loads potential, and cool between shots the time varying with the temp that day. I keep my guns clean and hunt with a Hoppes wet bore. I sight in with that condition in mind, ie. a clean bore thats damp with Hoppes for rust prevention here in KY's humid climate. It's a rare rifle that will throw that first bullet more than an inch out of group from a bore so conditioned. I picked up that little bit of wisdom from the Marine rifle team at Camp Perry. It works for all of my guns, but you should ck yours for their individual peculiarities. Hth's Rod

 

[North country gal]

A gun that maintains the same POI and accuracy, cold or hot barrel, is gold. Our 336A does that with the Hornady LE 160s. In fact, all of our Marlin 30-30s are pretty good in that respect, probably because the 30-30 is no super velocity cartridge. On our Marlins, at least, takes a lot of fast shooting to really heat up those barrels to the point where the POI starts to change or the accuracy suffers, significantly. I find that single loading keeps the pace slow enough to keep on shooting our 30-30s at a fairly steady pace, but I do touch the barrel, constantly, to check. I'm not the kind of shooter that burns up a lot of ammo at the bench, anyway. I like going slow (might be my age ) For us, the hot barrel and accuracy/POI shift is MUCH more of an issue on our bolt guns shooting higher velocity cartridges, especially through light sporter barrels.When that muzzle velocity gets up around 3000 fps, barrels heat up, fast.

 

[mrbb]

rule of thumb many folks like is if you place the back of your hand on the bbl and it feel HOT, its a hot barrel
BUT every gun will loose accuracy at its own temp/rate
I have a very accurate custom made light weight rifle, a thin bbl
after say 7-8 shots it will go from a 1/2 inch group, to a 3-5 inch group if I keep going
heat has a way of effecting all things, NOT just barrel, all metal when hot changes, most tends to get softer, and small changes can change many things from stiffness, vibrations, amount of flex,and so on
PLUS a hot barrel will loose rifling a LOT faster than a cold barrel or a warm one
yrs back when I used to take part in extreme testing of things, we used to shoot barrels to see how many rounds a barrel can take, from full autos to semi, or even a few bolt /pump guns(never tested a lever gun ?? don't know why)
but we have shot the rifleing out of many many barrels in less time than you think, more so on full auto's
and we have shot full auto's till the barrels melted and shot off the ends(don't recommend anyone do this)
hand guns have seem to be the best for NOT having heat related issue's, on most hanguns
super tight actions, and or all metal guns, can get hot to the point you won't shoot them without gloves, and most maintained a decent group, without a lot of growing in size groups that is
but I doubt very many folks want to take a sub 1 inch group pistol out and bang a few thousand rounds in a row out of it, or even a few hundred
without cleaning or taking a break
the amount of mags and loaders iof them and the costs seem to stop most folks if no other reason LOl

 

[swany]

Shooting for groups.

Foul bore with two shots. Leave the bolt open for air to flow through the bore. Get your .22 out and shoot some targets for practice.

Wait for 5 minutes after shooting the .22

Shoot one shot and leave the bolt open. Wait 5 minutes. Repeat.

Bolt action 5 round groups.

Lever action 3 round groups.

 

[Blackbarry]

Shooting for groups.

Foul bore with two shots. Leave the bolt open for air to flow through the bore. Get your .22 out and shoot some targets for practice.

Wait for 5 minutes after shooting the .22

Shoot one shot and leave the bolt open. Wait 5 minutes. Repeat.

Bolt action 5 round groups.

Lever action 3 round groups.

I guess you don't want the external barrel temperature above 125*F or so. Long waits with plenty of air circulation. Thank God I love my .22 Model 80 :biggrin:

 

[Doc Holliday]

I do as Swany says when I shooting groups.... I want that barrel to be as it would be if I had just taken it out to hunt, so the 2 fouling shots and wait with the bolt open for 5 minutes between shots. The reason to practice and shoot groups is to see where the rifle will shoot cold in a hunting situation.... unless you dont hunt, then you can do what ever you want to when at the range. I dont hunt with my 1911 so I blast through 100 to 200 rounds real quick to mimmick a gun fight, so I have an idea where rounds will go when the barrel is hot.

I always bring more then 1 rifle to the range.


Doc

 

[mrbb]

well I agree with a bunch, but the down time can vari a LOT pending outside air temp
when its a 100 degree's out, or if it -20 outside

 

[Sidespin]

Good info by all. As NCG said hotter loads will have a greater effect, however, my .35 heats up pretty quickly... thinner barrel walls than the 30-30, easier to heat.

That being said, when breaking in a barrel I purposely heat up a barrel with three, four or five shots only seconds apart (not for grouping), then allow the barrel to cool to an ambient temperature, Then shoot for group. In warm weather this cooling could take 20 minutes or so, therefore I always take three or four rifles to work with.

Ss

 

[GaCop]

A covered firing point versus being out in the open under a hot sun will also keep a barrel cooler while testing loads.....

 

[XMAN]

Never really gave this much thought but I do the exact thing that swany described.

 

[Doc Holliday]

Never really gave this much thought but I do the exact thing that swany described.

I thought you had.... I have seen your groups!!!


Doc

 

[XMAN]

I thought you had.... I have seen your groups!!!


Doc

I think I read it here some where before. I always figured to shoot 3 shot groups because I'm going for hunting accuracy and we all know that your lucky if you get a second shot of let alone a 3rd.
A good lead sled could make almost anyone look good off a bench. Lol

 

[truckjohn]

So.. It's not thermal expansion of the diameter of chamber or barrel ID.....
It's the relaxing/shifting of stresses in the barrel steel as it heats up....

During the barrel manufacture - barrels are straightened several times.... Sometimes, they shift around some as they heat back up....

The second thing is junk connected to the barrel.... Look at barrel bands, hand guards, forends, screws, sight dovetails, etc....
These things will ALL cause the groups to shift around as the barrel heats up....
Why not take these things out of the equation as much as possible....
Shoot slow.. Allow time between shots to cool down.....
Take along a 22 with you.... Fire one shot with your real rifle - then switch to the 22 and shoot that one while the barrel cools off....

Anyway... On load development/sighting in.....
You gotta know that whatever accuracy/inaccuracy you *Think* is related to the load is really not the barrel warming up and moving..... I have seen SO many folks at the range "Chasing the Zero" all over the place because they were shooting too fast - and the barrel was heating up and shifting around.. (Or more commonly - a bad scope or mount..).. Here they are blaming the "Load" when it has nothing at all to do with the load....

So...
What's the condition of the barrel when you are hunting?
Do you have the chance to fire off a couple quick warm up shots before you put the sights on your deer?
Me neither.....

The barrel is going to be stone cold and in whatever state you tend to leave it (Cleaned/uncleaned...)
SO...
The First shot is really the only one that will matter....
You are probably having problems if you are making 4 or 5 quick "Follow up" shots....

 

[North country gal]

You know, all of this is standard operating procedure for us old timers when accuracy testing and sighting in at the range, but I have been surprised more than once at the range by younger shooters next to me asking me if there was anything wrong when they see me shooting at such a slow pace. Had to explain the whole hot barrel/cold barrel thing to them. I sometimes forget that there is a whole generation of new shooters out there that didn't grow up with bolt guns and lever guns. Thanks for the good question, GaCop.

 

[PWB]

My wife once asked why I take so many rifles with me when I go to the range? Or she say may something like: Why can't you just take one! Of course I had to explain to her that one gun is simply not as much fun as a bunch of guns! :biggrin: Whether it's a bolt or lever gun I usually shoot groups of three,...after shooting I always leave the bolt or lever open and place the firearm in the shade...fortunately my shooting range has covered shooting benches. If I'm testing a new load I will give the rifle a bit longer to cool before shooting another group...about the only time I will shoot more that three rounds is when I'm shooting my .303 Lee-Enfield or M-4...these rifles are made for slinging lots of lead down range and still be reasonably accurate!

 

[Sneakybuffalo]

The main thing that no one has mentioned yet is the burn rate of your powder. If your barrel is hot, it will make the temperature of your round increase as it sits in the bore. This increases powder burn rate, which increases pressure, which increases velocity, which effects harmonics. You can test it with a chrono and the colder the ambient temperature the more noticeable it will be. This is a big deal when using maximum pressure loads.

That is unless you are using some of the extreme temperature powder by Hornady or other manufacturers, which varies very little based on temperature.


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[myflatline]

I can't figure out how to get that second deer to stay put for a minute or so while my barrel cools :biggrin:

 

[45nut]

Went shooting last Saturday, it was 102 degrees, I shot, walked up to check the target (100 yards), walked back, sorted some stuff, fired up a Blondie (it's a cigar), had a swig of my Gatorade, scuffed around a little, :flute: and the barrel was still pretty warm after some 20 minutes. Waiting for the barrel to cool in New Mexico could take awhile May through October. But, before I go hunting in the fall, I'll take a shot, then wait a half hour to 45 minutes before the next. I figure I'm only going to get one shot, if that, so it's how it shoots that one shot out of a cold barrel that is my only concern. I do love those guys with their semi-autos though, going through a half box of ammo in ten minutes or less.