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barrel cooling question

Printed From: OpticsTalk by SWFA, Inc.
Category: Firearms, Bows, and Ammunition
Forum Name: Shooting
Forum Description: Techniques, tips, stories, general discussion, etc.
URL: http://www.opticstalk.com/forum_posts.asp?TID=19254
Printed Date: November/18/2018 at 15:12


Topic: barrel cooling question
Posted By: nightranger
Subject: barrel cooling question
Date Posted: September/15/2009 at 15:01
How long should I wait between shots when sighting in a 30-06 rifle?  Do I take 3 shots in succession or do I wait a certain amount of time between each shot to let the barrel cool down.  How long does it actually take for a barrel to cool down.  I know it was still pretty hot after waiting 10 minutes after a group of 3 shots at the range.  What is the maximum shots I can take in succession before letting the barrel cool.  



Replies:
Posted By: jonoMT
Date Posted: September/15/2009 at 15:47
If your goal is to get a reliable zero for hunting, you should allow the barrel to fully cool between each shot. Ideally, you'll be out at the range when temperatures are fairly close to the average when you are hunting. If it's around 50-60F and I have the rifle in the shade, I find 5 minutes will easily do it. I've gone as long as 15 though. Also, keep your ammo at the same temperature - ideally in the shade.

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Reaction time is a factor...


Posted By: 8shots
Date Posted: September/16/2009 at 03:37
When I do 5 shot groupings I wait 1 min between each shot. This keeps the barrel cool.
 
I think the question remains why you want the barrel cool. It also depends on the ambient temp. On a really hot day the barrel can still be hot 1/2 hour later, whilst on a cold day 10 min is enough.
 
To avoid throat erosion and damage by overheating? Then I suggest no more then 5 shots in succesion and wait about 15-20 min before shooting again.
It must be said that I have shot my own rifles pretty hot (too hot to touch the barrel) and no immediate damage occurs. If one continually shoot a barrel to this point, then throat erosion will occur a lot quicker then if you kept the barrel cooler.
To achieve a good grouping and to avoid barrel "walk" ? Then 1 min between each shot, with a max of 5 shots.
To simulate hunting and the "cold barrel shot" then as jonoMT said above.


Posted By: Trays 7940
Date Posted: September/16/2009 at 08:48
I let the barrel cool 1- 5 minutes then check the barrel with my fingers.  If its still warm I let it rest some more.  However, I have not had to wait to much longer than 5 minutes...  If you are using a heavy barrel it will not heat up as fast as lighter barrels.  Time and touch, too be sure....   Bandito

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I don't shoot innocent animals, just the one's who look guilty.


Posted By: Terry Lamb
Date Posted: September/16/2009 at 10:51
Truth is rifles all have different personalities. But the cool barrel logic is unassailable. Your shot in the field will be from a cool barrel, so, ideally, your patterning at the range for hunting purposes should follow suit. On the other hand, my favorite hunting rifle does not begin to show stringing until after 5 or so pretty rapid shots, so patterns of three to five without cooling show excellent results, but after five they wander. Other rifles behave differently as a result of a wide array of variables, including barrel, bedding, etc. Nonetheless, to me, that first-shot-of-pattern is the most important for the hunter.

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Terry Lamb


Posted By: nightranger
Date Posted: September/16/2009 at 11:11
Thanks everyone for your info.


Posted By: robbie
Date Posted: October/18/2009 at 00:37
When you talk about loosing pattern based on a hot barrel, how much creep are we talking?
 
In other words, if all shots cold produced a 1" pattern, what would one expect the pattern to be after 5 shots or whatever causes a hot barrel?
 


Posted By: Terry Lamb
Date Posted: October/18/2009 at 11:45
My primary rifle, an 03-A3 Springfield, begins to string vertically after 5 or 6 uninterrupted shots. The impacts, at 100 yards leave the normal sub-minute group and proceed northward as much as 2 additional inches as heating progresses. In this gun, a straight line would indicate a movement to the 1:00 position, not perfectly vertical.
 
I want to emphasize again, that virtually all rifles will behave differently, because there are so many variables. However, I believe the greatest variable is the action/barrel bedding. Even so, this rifle has a floated barrel, with stock contact only at the chamber end.
 
Some rifles may exhibit minimal change of pattern with heating, while mine exhibits pronounced behavior every time. Nontheless, mine is a hunter, and in the field should never be challenged by the hot barrel at game-shooting time. The long-range varmint shooter might have entirely different requirements.


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Terry Lamb


Posted By: 338LAPUASLAP
Date Posted: October/19/2009 at 08:48
WHAT TYPE OF AMMO???

New factory, New Reloads...

Old Junk Surplus???

Cleaning method??? 

Also a Cold Bore Zero is different than a Warm Bore Zero....

Zero has 27+- Variables...


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No one


Posted By: Terry Lamb
Date Posted: October/20/2009 at 13:40
Originally posted by 338LAPUASLAP 338LAPUASLAP wrote:

WHAT TYPE OF AMMO???

New factory, New Reloads...

Old Junk Surplus???

Cleaning method??? 

Also a Cold Bore Zero is different than a Warm Bore Zero....

Zero has 27+- Variables...
Didn't know if you directed the question at me, but what the heck.
My 30-06 deer and elk loads are 51.0 grs 4895 under a Hornady 165 SST. The old rifle, however, begins to string hot regardless of the load.
Also, you did raise a good question about cleaning. I never hit the field with a freshly or thoroughly cleaned bore. My old rifle likes a "fouling" shot or two before it settles in to its excellent patterning. John Barsness has addressed this issue a few times. My theory is that oil/solvent residue and a lack of copper fouling in a bore cleaning down to original metal alter pressures enough to make a difference in these first few rounds' point of impact.


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Terry Lamb



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