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Understanding Cold Barrel Shots

 
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  #1  
Old 08-22-2013, 01:21 AM
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Join Date: May 2011
Posts: 13
Understanding Cold Barrel Shots

I live on a farm in the Western Cape of South Africa. It is very mountainous, with various flat sections, divided by gorges and valleys. We farm apples and pears. We have a variety of wild life, which we thoroughly enjoy having. However, one of our frequent visitors and borders, are baboons. In summer these baboons can cause considerable damage to fruit trees, as well as decimate crops.
Our only significantly effective management is to shoot selected baboons in the visiting troops, to ensure that they understand the "No go Zones" clearly. It is very effective, and since we have a dedicated professional hunter employed to manage the troops during this time, we experience great success.
Obviously, this form of management is frowned upon by various groups, but we can honestly say that their alternate management styles, fail dismally, with some having short term effect, if very little at all. These range from monitors, electric fences, trenches etc.
However, I also often shoot specimens out of season, when they start using my apple trees as a jungle gym, and youngster training grounds. With obvious damage occurring. So, I remind them of the boundaries set in summer.
I shoot a Remington 700 Varmint SF, with a CHOATE "John Plaster" ultimate sniper Stock, and a MTC Taipan 6 x 24 x 56 Scope. (I know! Not a fantastic scope, but all I can afford, while saving for a NFX zero stop). I have a rifle level fitted, and load my own 168gr Sierra Match King in Lapua Brass, with match primers, at almost full power load. I do Ogive measures and recently started Molly Coating the heads. I have an exbal balistic shooting chart, which I have tested and adjusted up to 800 yrds.
I have some trouble with grouping at 100 Yrds, with the first shot (Cold Barrel) being about 1/2" high , consistently. This is without Molly coated heads. I am hoping that the Molly will help reduce the variance in placing of the first shot. I can now adjust for this reasonably well, but it still an "Unknown Variable" which reduces my confidence on a first shot. Especially, when many shots are beyond 300 Yrds, and often up to 700, and on a reasonably small target.
I am trying to find some good reading on this "Cold Barrel" shots, and how to overcome it, if it is at all possible, or is it just my rifle? I have a friend highly experienced and trained in long range shooting, who shoots without having this problem.
I would greatly appreciate any advise, or directions to good reads, on this topic.
Thanks to you all who put valuable information on this site. I have learnt much from all your pains and successes, which I know often come hard by. I appreciate it very much.
Regards from the RSA!
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Old 08-22-2013, 08:09 AM
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Join Date: Jan 2004
Location: Blackfoot, Idaho
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Re: Understanding Cold Barrel Shots

Very well written post!

Given that your cold bore shot is consistently 0.5 MOA high you should have confidence I it? Or do I not understand something?

I'm assuming that the cold bore shot you mention is not a "clean bore" cold bore shot?

How many shots at one time are usually taken. I wouldn't think those critters would not hang around very long after that first shot?

Rather than upgrade the rifle for one that puts the first shot with the of the group I would simply hold 0.5 MOA low on subsequent shots.

With an MOA reticle this should be straight forward.

There may be other ways to compensate but holding off on subsequent shots seems an easy way to go.

It would also be good to know how long between shots it takes to attain cold bore status.

Hope this helps.
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Old 08-22-2013, 09:05 AM
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Location: Carey, Idaho
Posts: 982
Re: Understanding Cold Barrel Shots

Quote:
Originally Posted by royinidaho View Post
Very well written post!

Given that your cold bore shot is consistently 0.5 MOA high you should have confidence I it? Or do I not understand something?

I'm assuming that the cold bore shot you mention is not a "clean bore" cold bore shot?

How many shots at one time are usually taken. I wouldn't think those critters would not hang around very long after that first shot?

Rather than upgrade the rifle for one that puts the first shot with the of the group I would simply hold 0.5 MOA low on subsequent shots.

With an MOA reticle this should be straight forward.

There may be other ways to compensate but holding off on subsequent shots seems an easy way to go.

It would also be good to know how long between shots it takes to attain cold bore status.

Hope this helps.
Yeah, what he said. As long as you know where the cold bore shot is going, you are in the money. And I don't think you have an issue as long as it stays consistent.

Randy
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Old 08-22-2013, 09:15 AM
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Location: North of Eden-South of Heaven, Wy.
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Re: Understanding Cold Barrel Shots

I learned from a shooting class that for hunting you need to set up a cold bore zero. Most of the time you only get one shot or maybe two before the game is dead or gone. Shooting a fouled barrel you only take two shots and make that your cold bore zero. You can use a different rifle if you want to shoot more but only two shots from each rifle and set your cold bore zero. Check the rifle the next morning and when you get your cold bore zero you are ready to go hunting. If you are target shooting then this will not apply.
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Old 08-22-2013, 10:05 AM
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Join Date: May 2011
Posts: 13
Re: Understanding Cold Barrel Shots

Hi Guys, wow what a great response from you all. Thanks!
Yes, the 1/2 inch is reasonably consistent, on warm days. On really cold mornings, it gets closure to the bull, below 10 deg Centigrade, in the centre.
I forgot to mention that the rifle has only shot about 150 rounds, and that every cold shot, was with a perfectly clean barrel. In speaking to a very experienced shooter this afternoon, I may have come slightly closer to understanding the problem.
He recons that firstly, i could have bore cleaning residue, as I only put a single jag through before shooting, after the barrel was cleaned. this could be a contributor, as not all the solvent was necessarily cleared. Thus a faster higher shot. Secondly, and I think more pertinently, the barrel may not be completely broken in yet. Seeing, that I am cleaning the bore after every shooting session, properly, I may be cleaning most of the copper out of the tiny machining pits in the barrel.
He suggest I try and do a lessor clean, and definitely not polish out the barrel, and then do some groupings.
This may allow the machining holes to stay filed, and slow the first shot as per the 2nd and 3rd etc.
As a test I'm going to shoot 3 shots, and then simply, nylon brush the bore 3 times, and put a dry jag through. Then do a 5 shot group the next day, with a cold shot included, and see how they group.
To answer the questions you posted. I shoot a 5 round grouping with a couple of minutes between shots. No fast firing.
I'll post the results with the trials above.
Thanks again !!
now off to
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  #6  
Old 08-22-2013, 10:11 AM
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Join Date: May 2011
Posts: 13
Re: Understanding Cold Barrel Shots

Oh, Roy, I hardly ever shoot more than two at a time. Correctly stated, the troop usually scatter for the hills, after the first shot. However, we do get the odd "new" troop, that are gun dumb! They usually do not really know what to do, and run in all directions, or just sit and look at each other, well that is until the next two shoots follow, and then they figure out a hiding place may be on the cards, and fast! Most I've shot at once is three. Them critters are slippery at full pace, and they scale rock faces like lizards!
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  #7  
Old 08-22-2013, 10:49 AM
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Join Date: May 2008
Location: South of Canada and North of Wyoming
Posts: 5,954
Re: Understanding Cold Barrel Shots

Marcel, Welcome to LRH?

Most rifles will have a POI shift from clean to fouled bores. To minimize that, I try not to clean until needed... i.e. bore gets dirty or accuracy starts falling off. After cleaning, if I intend to use the rifle in the field for hunting or what ever, I will foul the bore and check zero. At that point there should be no shift in cold bore shots. If there is, there may be a problem with action bedding or scope mounts, etc.

In the last year or so, I have come to the same way of thinking as your friend who recommends not cleaning the bore completely free of copper and carbon... unless I plan to put it up for a long period of time.

Cheers
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