barrel heating

[cbourbeau32]

I am planning to get out to the range this weekend sometime or next weekend for sure and shoot some of my recently reloaded 7mm 08 and 243 rounds in my Handi's and have a question. I have shot guns for over 20 of my 36 years but never have developed a "sight in procedure". What I am wondering is this: can I shoot 3 rounds groups one shot after another then let my Handi cool while I shoot another caliber then come back and shoot 3 more as long as I allow sufficient time between groups? Also what wait time do most people use between groups (I know this will depend some on outside temp)? Thanks, Charlie

[trotterlg]

People way overwork the barrel heating problem.  If you can still touch it for 5 seconds it is not too hot.  Larry

[LaOtto222]

I do basically the same thing. I lay my hand on the barrel and if it is too warm to be comfortable then it is too hot to shoot (for me any way). As you shoot take note if the barrel walks (checking the heat of the barrel as you go). I can shoot 5 in a row and the barrel will feel cool. Wait a couple of minutes and it will feel warm (not hot). takes a little while for the heat to get to the out side of the barrel. Oh, I shoot mostly 22 caliber center fires and the small ones too. I can shoot a 10 shoot string in any of them and not over heat the barrel. I usually do not shoot much more than that before giving them a rest, but that is because I usually have more than 1 gun I shoot at a time, not because they are too hot. I do that so when shooting 1 string and comparing them to the next I have the same reference point for each load/string. If I was in a PD town and really blazing away. I would stop if I could not keep my hand on the barrel for more than a few seconds. Even If you can not keep your hand on it for more than a second, it still is not hot enough to warp it. It would have to get up to 300 degrees or higher (I am estimating this, based on oven heating finish coatings) to warp a barrel and I think you would burn your hand as soon as you touch it. If it burns your hand, then it is too hot to shoot.

[oneshotonekill]

Barrel heating is an interesting topic that I think many people miss the point on.  Heating of a barrel is a disproportionate process where some areas (the throat) are much hotter than others.  Since steel is a conductor of heat the barrel will try to reach an equilibrium temp so the heat spreads through out the whole barrel over time.  This is why it takes a while to feel the exterior temp of the barrel rise.  Many people think that because they can set their hand on the exterior of the barrel at some location for a few seconds that the barrel is still ok to shoot, however the bore and throat could be several times hotter than that exterior surface.  The true threat of shooting a hot barrel is not warping but erosion of material in the throat and bore.  Once the steel is hot molecules will flow causing small particles to be vulnerable to being removed by hot gasses.  Each shot is like exposing the throat to a cutting torch, when the steel is cool the torch mearly starts heating the material, once it gets hot enough it starts cutting.  Some calibers are much more prone to barrel heating due to powder capacity, bore diameter, etc.  The material of the barrel will also play a factor but in reality a person could ruin a barrel in one session by shooting it too hot.  As a general rule of thumb the larger the bore diameter for a given case capicity the more shooting/heating you can get away with with out erosion.  Using your 2 calibers as an example the 243 and 7-08 are based on the 308 case.  The necking down to 244 causes the gas volume of the case to squeeze through a much smaller opening than say the 308.  That concentration of the gasses is what accelerates localized heating and erosion.  Think of your garden hose flowing at full pressure then wrap your hand around the opening to restrict the exit diameter and see what happens.   

[~Ace~]

I have messed with Metals a time or 3 in my life.. Heating them never presented problems, it was how Quickly they cooled that decided what you had left.  So, Lets add a twist, how does Cooling your Barrel effect it's life ? And can a "light weight" Barrel cool to slowly and anneal it's self ? Can a Bull Barrel Draw the heat away from the chamber to Quickly and cause it to be Tempered ?

Why are all Select fire weapons built with light weight barrels ?

[edgemark]

Unless your barrel is getting into the 400 degree F area I doubt that this should be a problem, and even that is the low end of the tempering range.

edge.

[Mac11700]

I have messed with Metals a time or 3 in my life.. Heating them never presented problems, it was how Quickly they cooled that decided what you had left.  So, Lets add a twist, how does Cooling your Barrel effect it's life ? And can a "light weight" Barrel cool to slowly and anneal it's self ? Can a Bull Barrel Draw the heat away from the chamber to Quickly and cause it to be Tempered ?

Why are all Select fire weapons built with light weight barrels ?

Barrel heating will erode the edges of the rifling much quicker than many believe..even with smaller calibers...Most rapid fire selectable weapons aren't looking for bench rest accuracy..but being able to hit a man size target to wound...less emphasis is put on how accurate it is but more on durability...and how well it will function..in the most extreme conditions...Oneshotonekill has explained this process very well...

On a side note..there is a way of reducing the barrel temps..and that is by using a coating process..like Moly Fusion..From my limited testing this product seems to lives up to it's claims..and the owner is a site sponsor here..When I have time..I'll try to find my testing of it with 2 25-06's..from last year..The product didn't allow the barrel to heat up near as fast..and it cooled off faster..Others have used it as well...and I will be doing more testing with it on my new Savage and Winchester bolts guns as well as  my CVA's...

Mac

[bluebayou]

Personally, I just whale away with my 223 Savage.  It takes A LOT to heat up and it can be rebarrelled easily enough for cheap price.  The Handi, the M70 seems prone to heating up very fast (is 270), the Remington in 7-08 heats up slowly, but it has an outstanding bedding job on it and remains very consistent. 

The 223 Handi that I formerly owned had a lug that was too tight on the FRONT of the forearm hole.  As it got hot it would walk shots up the page.  I relieved the wood with a knife and file and it shot much better. 

My take has always been that it is mainly an issue of erosion in a properly bedding/constructed rifle.  The SKS's limited accuracy goes to pot very quickly, for example, because it has a gas tube, piston, poor bedding/inletting, etc, that heat/cool and expand/contract at different rates.  I agree with the explanation from Oneshotonekill, but I will qualify it by saying that 3-5 shot groups are not a big deal IMHO.  Automatic weapons are a different animal.  Sustained fire weapons have open bolts, changeable barrels, etc.

[DalesCarpentry]

I do alot of shooting and I really have never heated a barrel to the point you could not hold it for at least 5 seconds. I feel why take the chance of ruining the barrel. One of the main reasons I never let them get that hot is the Handi's tend to climb the hotter they get. Sometimes as much an inch.

[cbourbeau32]

Thanks for all the responses. You answered my question. Charlie

[xhare]

One of the reasons I have never bought a used rifle chambered in a cartridge like a 22-250 or 243 is that you cannot be sure of how it was treated by its previous owner.  While ANY rifle can be shot out, the ones chamber in cartridges that have less powder/larger bore are more likely to withstand abuse.  Further, those small bore powerhouses tend to be used for varmint shooting (read more shooting) than the larger "big game" rifles (read less shooting).  In general anyway.

I have never shot one of my own rifles to the point it was too hot to handle except for a Mini 30 after I blew through a 30 round magazine.  However, I was in the Security Police in the Air Force and had occasion to make several M-60 machine guns smokin' hot requiring barrel changes (and this was even though I was keeping the rate of fire down with 5-6 round burst), and I have also made the gas tube of an M-16 glow red during night fire range time.  Of course barrel changes are part of the training on the M-60.  It should be noted that even blank ammunition will heat an M-16 or M-60 barrel enough to make it glow in the dark. 

One other note, I have been at the range on hot summer days and just letting the gun lay in the sun can make it to hot to comfortably handle.  I usually keep them in the case till I want to shoot them to avoid this problem.  I also keep ammo in the shade when possible.