40 Rod has a large bbl 16 sided if I remember correctly - 
chime in 40 Rod - u all have a good day now - rimfire

Isn't the whole idea of a large diameter barrel that it NOT get hot as you shoot it?   

Whatever temp that mass of steel has is going to have a lot of thermal inertia due to its heat capacity, so whatever temp change it has is not likely to be very fast.  JMHO... 

Froggie

Dale. I feel that I must respectfully disaggre with you regarding the warming up of .22 barrels.    It has been my experience of over 50 years of small bore shooting, both indoor and outdoor that MOST barrels require a few shots to warm up the interior of the barrel. Not that the barrell will get hot as you note (in direct sunlight). Having shot at many different locations in the States, Ceneral and South America I have found that the rifle will place the first 2 - 5 shots in a different location than the true zero location. I routinely fire 5 shots "INTO THE HILL" before going to my target. I have had many rim-fire rifles from a early Winchester 52, a Winchester 52D, Several Anschutz, Remington 40x and two BSA Mk II and MKIII which I still have and shoot. ALL preformed better with warm up shots. I beleve the heaver target barrels tend to reduce or eliminate barrel vibrations and does reduce warming in a long shoot. AS far as the centerfire barrels being heavier there are several reasons. Resist getting hot, regidity for much reduced barrel "whipping", reduced recoil, and they look "neet"!  
My BSA MK111 using Winchester MK3 ammo will and has shot many"possables" at 50', 50yds, and 100yds. I think I shot a 247 one day at EG. (3 leakers)     Much Fun all the way around. I still have several bricks of MK3 and NO, it's not for sale!!! 
I also beleve that many fine .22 rf target fifles have been ruined by over cleaning. I only clean once or twice during a season and then only with a patch with Hoppies and then dry. It takes several rounds to bring it back to true zero. Always clean from the breech end!  
I hope to resume my shooting shortly after my eye surgery this Friday. I will be in touch. Don't forget my photo prints.  4227

Hello Martin. Good question. I really think it's a matter of warming up as opposed to new lube. Between relays before flagging you action became the norm safety practice I would place a fired case in the chamber with the action open to keep the breeze wafing thru. If the break was longer than I liked I would again dump several rounds into the bank before going on my official target. In the Canal Zone at the Balboa Gun Club we has the target frames for small bore on a trolly tract that went to 100 yds so we didn't have to walk down and back. Made target changing a lot faster and easier!  The fresh lube thought may be valid also. I don't know. I do know however I had better not go for record at the start.   I developed the practice of dumping 5 shots before go on the record target sighter. At 50' we shot the A-36 target and the regular NRA 50 yard 5 bull for both 50 & 100 yd. All out doors. The Balboa Gun Club was a Great Range. Wonder what ever happened to it after we gave the Canal Zone away?

We are not actually in disagreement here. It is a matter of semantics. What I can bore conditioning, you call "warm up". Some time ago I did an article on the .22's which covered this in some detail. The info I got from actual firing tests.

Again, we are NOT in disagreement but merely using different words to say the same thing.

I hope to get back from North Carolina Sunday evening. Hopefully, in the following week I can get some obligations satisfied. 

I would not, at all, mind a  "reminder" e-mail. I do not wish to disappoint anyone but being out of state for a couple of weeks has my so-called brain a little behind times.

Dale53

If you like Mr Calfee's articles (and I do also!), you might wish to join the Smallbore Journal web forum (part of the Shooters Journal pages shootersjournal.com) and read some discussions by Mr Mike Ross of Ross Precision.
He has many points of agreement with Mr Calfee's writings, and also has some fascinating ideas himself that have been tested by some top-level smallbore prone shooters, and have not been found lacking.

Paul F.