Cooling Down While Working Up


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HARV6
March 29, 2012, 11:56 PM
When you're testing groups of different charge weights for a rifle, how long does it take you? I've only ever tried once before and it took me forever because I tried to let the barrel completely cool to ambient temp before each shot. It literally took me months to do because I'd only shoot about 5 rounds an hour, call it quits, and then it might be a month or more before I made it out to shoot again. That rifle went down the road after realizing I wanted some different features in my hunting rifle. Now I'm working up some loads for my new hunting rifle and trying to plan how to test them in a reasonable amount of time. This time I'm going to shoot 4 rounds in a minute or two...clean the barrel, let cool to ambient temp, and repeat. Is this reasonable or am I still over doing it?

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Ky Larry
March 30, 2012, 12:16 AM
I shoot 3 shot strings and let the barrel cool for about 15 minutes. If I'm shooting a .30-06 or larger, I wait at least 20 minutes between strings. Since I usually take 3 or 4 rifles and a couple of pistols, I don't spend much time doing nothing. Also, I've found rifles cool much faster if they are leaned up against the bench with the muzzle up and the action open.As the warm air in the barrel rises, cool air is pulled in the breech like a stove pipe.

bds
March 30, 2012, 12:22 AM
When I do powder work up with my .308 rifle, I will let the barrel cool to the point I can touch the barrel without discomfort. I guess you could use a contact/laser thermometer for more consistency.

FROGO207
March 30, 2012, 05:48 AM
As with anything one can overdo it.:) I will do a workup with a short time between shots--1 to 2 minutes for 4 shot groups. Then wait until the barrel is noticeably cool to the touch and repeat. After I get a good load developed I will take more time between shots/groups and see of it improves but the key is not waiting so much when first weeding out the really poor loads. Also when trying for max accuracy test at the barrel temp that you plan on using when shooting. For P dog hunting a cold barrel will not be the best choice for example as you will be shooting often with a warm barrel.

gamestalker
March 30, 2012, 06:17 AM
I shoot 30-06, .270 win, 7mm RM and a few other common HP cartridges. I do 3 shots cool don for 15 minutes, and then another 3 shots. When considering cool down, it isn't necessary to cool down all that much. In fact once the barrel is consistently heated up, and then kept at a fairly consistent temp, it will soot very consistent in most circumstances. So even 10 minutes between 3 shot strings will do the trick.

But I suppose if you are concerned about your group opening up .010", it might be advisable to use a thermometer to keep things consistently the same from shot to shot. I know a guy that does this. He shoot 2 rounds back to back and takes the barrels temp internally 5 minutes after being shot, thus using that temp as his shooting temperature. Of course he takes an oral temp rather than rectal, because the barrel gets hotter down towards the muzzle than at the chamber he says.

But regarding your concern, I think you might be over killing the approach. It shoudln't take months to work your loads up. Using 3 shot strings, with 15 minute cool downs, will allow you to print 15 rounds per hour. If your shooting anything that produces uncomfortable recoi,l I would say 2 hrs.., or 30 rounds printed, is going to cause your groups to degrade simply due to recoil fatigue. So either way you end up with some form of limitation, as to, how many rounds you or the rifle can handle effectively and productively.

Blackrock
March 30, 2012, 07:29 AM
For my Varmint rifles (.222rem, .223rem and 22-250) I expect to shoot them on the Dog Towns in SD all day long sometimes so I work up loads the same way. I work to find a load that will shoot consistently with a fairly warm barrel. These loads are generally two notches under listed max load. I have two rifles in each of the calibers and take 2K rounds with me every spring.

For my deer rifle I expect one shot cold barrel accuracy and only shoot one round in 10 minutes when I worked up a load for it. Once done I was good to go and never messed with it again.

blarby
March 30, 2012, 07:35 AM
I always select firearms with their dual nature in mind.

1/2" doesn't bother me.

Any load for me needs to be able to shoot hot, often.

Thats me...i'm weird that way !

capreppy
March 30, 2012, 11:25 AM
For hunting loads, cleaning the barrel during your workups may give you some inaccuracies. Typically (from what I read as I am not a hunter...yet), you'll foul the barrel at the beginning of the season (usually when you check your zero) and then leave it fouled for the season. You'll get different results if you clean the barrel as often as you state above.

kingmt
March 30, 2012, 03:46 PM
My post would repeat Blackrock.

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