Advanced Marksmanship cold bore shot, how long ...

[cdennyb]

OK, every time I go out to the range, my first shot of the day gets logged in my CBS data page entries log. But... how long between the last shot of the day and the first shot of the day would you consider minimum for the first shot to be a "Cold Bore Shot"?
Some say, the next day, like 12-18 hrs later... some say 6 hrs. what do you experts say? How long between shots could we consider the next round to be an accurate cold bore shot to log as such?

 

[karux408]

Re: cold bore shot, how long ...

'cold bore shot' is based on temperature, not time. Otherwise, they would call it 'next day shot'

For absolute precision, get a thermal camera, benchmark your bore temperature, record environmental conditions (e.g. sun on barrel, humidity, current air temp), mark time, fire a shot, wait for the thermal camera to verify bore temperature has dropped to benchmark, mark time elapsed.

for less precision, shoot-wait-shoot, notice variation, repeat shoot-wait-shoot.


for a specific rifle, varying environmental conditions should cause variations in the time elapsed (and how cold a bore). across various rifles, time elapsed should vary based on heat sinks attached to the barrel, receiver, and bolt.

 

[cdennyb]

Re: cold bore shot, how long ...

The reason I asked was that I DID use a temp indicator on the barrel. I did some CBS at the range when it was around 40 degrees out... Now it's in the 70's so the cold bore shots I took back on the cold days are far from the shots I take now. So... a question would be, which ones are true CBS's? See my problem? A cold day in summer is hotter than a warm day in winter, so the data would be significantly skewed. I would think the data from the shot is really only relavent during the weather window of the common temp days.

 

[HillbillyfromAL]

Re: cold bore shot, how long ...

It's cold bore shot's don't you guys know that they are all cold bore until the barrel get's hot? That's why those first ten or so may not line up with all the other's. Then say from 11 and on it's a hot bore so that can throw the rounds off too.

 

[Lowlight]

Re: cold bore shot, how long ...

Guys heat has very little to do with it unless you are shooting pencil thin barrels, or your gun is screwed up.

Metal doesn't work in the fashion that 1 shot will deviate then the rest settle in, if it did all rounds would walk and you would never group as the heat is constantly multiplying. If you see heat induced deviate you have a bad barrel or rifle / as in the threading at the action is sub par.

Cold bore shots are not because of a cold barrel versus a 1 round hot barrel, or 10 round hot barrel, that follows no logic.

What this video of how a rifle should act,
<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/3UZ-mApuUoM&sns=em"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/3UZ-mApuUoM&sns=em" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

No heat induced shift.

Today's more common understanding is the shooter causes the problem, not the rifle, caveated if it is 100%

 

[Graham]

Re: cold bore shot, how long ...

It's about knowing whether your rifle has a cold bore deviation. Most good ones don't. Some good ones do. I don't record the shot until I shoot it, which gives me the info I need. A duty rifle should not have a mechanical devation, but some do. It doesn't really matter as long as the deviation is consistent and you know the rifle. Here's a target that Frank shot with my cold AE. At a match, first shot of the day I always add .3 Mils elevation. After lunch there is no deviation.

 

[marduk185]

Re: cold bore shot, how long ...

for my junk ive found clean or fouled is noticable poi change. hot or cold not so much.

 

[kentactic]

Re: cold bore shot, how long ...

yeah let me speed up the learning curve because i asked a similar question not long ago..

temperature dosent affect POI. fouling affects POI. if you clean your rifle after every shoot and remove all fouling youll have a shift in POI until the bore fouls up. like in lowlights video. ive smoked my barrel and found no shift in POI. i always THOUGHT i was seeing temperature affect POI but it was just my shitty shooting. now that you KNOW that barrel temp isnt suppose to affect POI go shoot again and see if it magically goes away. it did for me..

 

[cdennyb]

Re: cold bore shot, how long ...

@ Kentactic
OK, that's what I was waiting for... I dragged out my data book and compared all the conditions over 4 months of shooting and the CBS all seemed to be in the same .50 MOA group. I was dragging a boresnake thru after shooting and then right before I did my first shot of the day. I like your thought process about shitty shooting being "MY FAULT". I can accept that. I can also accept the fact that I can shoot good, especially if I tell myself that I can. LOL I guess that's why I have good days and bad days... sometimes all on the same day.
The problem with agreeing with you is that I now have one less condition to blame my poor performance on.

 

[gugubica]

Re: cold bore shot, how long ...

I am not a big believer in the mechanical cold bore deviation. I do find it interesting though that my cold bore correction on my AE is the exact same as Grahams. 3 tenths low for the first shot of the day.

I have not had any verifiable data on any other bolt rifle I have owned, just the AE and an AR I used to own. Both were (are) very predictable and neither changed with ambient temp.

The rifle that has a legit CBS is pretty rare though.

Make sure you record everything. One session, shoot a shot immediately, the next time, dry fire a bunch before your first live round, mix it up. Over time, this method may prove very enlightening.

 

[sobrbiker883]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gugubica</div><div class="ubbcode-body">
Make sure you record everything. One session, shoot a shot immediately, the next time, dry fire a bunch before your first live round, mix it up. Over time, this method may prove very enlightening. </div></div>

Now CLEAN cold bore...that's an animal unto itself, one that I play with as little as possible. When I clean my bore I plan I smack steel with 10-15 rounds before I'm confident it will go where the barrel's pointed. I probably could log me CCBS's better, and will am trying to do so in the future (but I've said that before too).

 

[Guest]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">Now CLEAN cold bore...that's an animal unto itself, one that I play with as little as possible. When I clean my bore I plan I smack steel with 10-15 rounds before I'm confident it will go where the barrel's pointed. I probably could log me CCBS's better, and will am trying to do so in the future (but I've said that before too).
</div></div>

After cleaning the barrel to your liking, swab the bore with a clean patch soaked in lighter fluid, twice. If done correctly there will be a white powder left in the bore. That powder will be as slick as the graphite, your powder leaves after each shot.

My first and the rest are all in the mix, clean, dirty, cold or hot. Could be that Pac-Nor is different, but my Rocks do the same thing with that treatment.

Then again, I do believe there's a difference between a cold shooter and dry bore.

 

[gugubica]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body"> CLEAN
</div></div>

What is this clean you speak of? I don't understand.

Seriously, I don't clean my barrel so I don't worry about CCBS.

 

[GuyCoker]

Re: cold bore shot, how long ...

Is this a common method, to never clean your barrel.



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gugubica</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body"> CLEAN
</div></div>

What is this clean you speak of? I don't understand.

Seriously, I don't clean my barrel so I don't worry about CCBS.

</div></div>

 

[Slickrick0999]

Re: cold bore shot, how long ...

cold bore shot x KMW = same as the rest of the shots!

 

[sobrbiker883]

Re: cold bore shot, how long ...

Interesting. I'll try that in another 600 or so rounds when I clean my bore again....

 

[Slickrick0999]

Re: cold bore shot, how long ...

dont know about the clean cold bore, i very seldom clean my rifle. As long as accuracy is holding, there is no cleaning at my place

 

[sobrbiker883]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Guy Coker</div><div class="ubbcode-body">Is this a common method, to never clean your barrel.
</div></div>

To clean a bore before the accuracy wanes is akin to wiping your ass before you crap.

 

[blklabs]

Re: cold bore shot, how long ...

LOL!

 

[Dylan in AZ]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">To clean a bore before the accuracy wanes is akin to wiping your ass before you crap.</div></div>
Now there, is one heck of a quotable line!

 

[Slickrick0999]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Guy Coker</div><div class="ubbcode-body">Is this a common method, to never clean your barrel.
</div></div>

To clean a bore before the accuracy wanes is akin to wiping your ass before you crap. </div></div>
ROFLMAO!!!!!!!!

 

[sobrbiker883]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TerrorInTheShadows</div><div class="ubbcode-body">
Now there, is one heck of a quotable line! </div></div>

I used it 3 times now, its mine! Actually its paraphrased from teh guy that brought you the "barrel break-in video" on you tube (NOBODY).

 

[bigngreen]

Re: cold bore shot, how long ...

I've had a couple rifles with definite cold bore issues but all were solved by truing the actions and getting rid of as much of the mechanical stress as I could. A mechanical cold bore issue will show up within a shot or two with a POI change irregardless of ambient temp. If an ambient temp change changes your POI a guy needs to look at that as a possible POWDER TEMP issue and start tracking that. IMO.

 

[George63]

Re: cold bore shot, how long ...

30F in ambient temp will not have much affect on air drag /drop about 1/10 moa at 200yds for 308 so other than mechanical it would be powder

 

[Sterling Shooter]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: George63</div><div class="ubbcode-body">30F in ambient temp will not have much affect on air drag /drop about 1/10 moa at 200yds for 308 so other than mechanical it would be powder</div></div>

1/10 MOA, is that a fact?

 

[blakheaven]

Re: cold bore shot, how long ...

Never cleaning you rifle? what madness is this? I was always taught you clean your rifle after every outing. Is there a middle ground say just running a bore snake after every outing then actually using cleaner every month or so? I have heard of people not cleaning until ever 200 rounds or so but not "ever" cleaning. Are the accuracy gained by this really worth while?

I can see that barrels fouling being plugged up by this but I also see as the dirtier the rifling gets, the more friction placed upon the bullet slowing it down (thank you Newton) causing different MV than say a couple weeks ago when you first started shooting w/o cleaning. (My big hang up on accuracy is consistent MV cause with a consistent MV the bullet should be impacting the same place vertically cause the only variable vertically is MV cause gravity is constant, that is if you are shooting in the same atmospheric conditions)

Wind is another story...

 

[psmith]

Re: cold bore shot, how long ...

In my experience the CBS deviation has more to do with the barrel and action than the temp. My stock Remington 700 was always had a 1/2 moa deviation no matter what, while I haven't noticed much if at all with the Bartlein and trued action.

 

[MALLARD]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sterling Shooter</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: George63</div><div class="ubbcode-body">30F in ambient temp will not have much affect on air drag /drop about 1/10 moa at 200yds for 308 so other than mechanical it would be powder</div></div>

1/10 MOA, is that a fact? </div></div>

is that a 1 or two shot group ?

 

[jwoolf]

Re: cold bore shot, how long ...

Ok, obviously there are "some" rifles out there with cold bore shifts... what could they be:

1.) mechanical cold bore issues
2.) clean bore issues
3.) heat effects of the chamber/ammo

With some powders, I think we should all agree that hot cartridges impact higher than cold ones so, with older powder leaving a round in the chamber will absolutely impact different than your cold bore shot.

Also, a clean bore is physically different than a fouled one so, that's not a hard sell for me either.

Now, the big debate is all about mechanical changes or the possibility of them. In my own rifle I have a trued action etc. I also have a poi shift from first shot of the day to the second and it is now .5 moa low and .5 moa right with amax bullets... it's .5 moa high and .5 moa left with smk bullets.

I'm going to throw out a theory... what if it's because I am currently using a button rifled barrel that can not be as stress relieved as say, a cut rifled barrel. A cut rifle barrel does not have to be stress relieved in the first place so, could that be the issue? I personally think it probably is. After all, this would be a mechanical shift in where the barrel would be pointed downrange... a small one but, I believe it is possible. My new barrel won't be button rifling so, I'll know in the next couple of months if that is the issue with my rifle. Hell, I may be overcompensating by buying a #10 MTU contour for my next barrel.

And, before anybody says it's me causing the impact shift... I know how to shoot a rifle and, I've been doing it a long time... if I can make the president's 100 with a 4.5lb trigger shooting service rifle, I can shoot off a bipod with a 1lb trigger with a muzzle brake.

There is an undenyable poi shift in the very first round downrange in my rifle and, I do believe it is caused by a button rifled barrel that must move just a tiny bit after the first round of the day.

Honestly, it's not that big of a deal since it's very predictable in where the first round will go every time and honestly, .5moa isn't that big of a shift in the first place but, it's there.

I'd put money that it's the barrel. It's a lothar walther 26" 1:10 spin barrel. I put about 1200 rounds down range with it last year and it's beginning to open up a bit... it's not always shooting .35" groups anymore... Can't wait to post what I find with the Kreiger.

Of course, as with anything as complex as building a rifle, I'm sure it could be several things. I'm having my gunsmith have a look over the rifle when he gets it... he'll have to re-bed the rifle with the new barrel... at least the part in front of the recoil lug anyway.

 

[HillbillyfromAL]

Re: cold bore shot, how long ...

Your kinda thinking about it in the wrong way. Think of your rifle like a piston in a engine. If it's fouled meaning tiny bits of copper have filled all the little pits and voids of the metal it's the same as a well lubed engine. If it's really clean the barrel takes little pieces of coppr off the bullets jacket to fill those voids, like a cylinder would do to piston rings if there were no oil. That's why companies like Otis have made the life liner ceramic coating, and there's also smooth coat the proper way to apply moly. However running a dry boresnake through would really only remove powder residue, and it only takes one pass.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: blakheaven</div><div class="ubbcode-body">Never cleaning you rifle? what madness is this? I was always taught you clean your rifle after every outing. Is there a middle ground say just running a bore snake after every outing then actually using cleaner every month or so? I have heard of people not cleaning until ever 200 rounds or so but not "ever" cleaning. Are the accuracy gained by this really worth while?

I can see that barrels fouling being plugged up by this but I also see as the dirtier the rifling gets, the more friction placed upon the bullet slowing it down (thank you Newton) causing different MV than say a couple weeks ago when you first started shooting w/o cleaning. (My big hang up on accuracy is consistent MV cause with a consistent MV the bullet should be impacting the same place vertically cause the only variable vertically is MV cause gravity is constant, that is if you are shooting in the same atmospheric conditions)

Wind is another story...</div></div>

 

[notyers]

Re: cold bore shot, how long ...

When you shoot cheytac size rounds you do what works. I will clean my barrel when it looks bad inside or when accuracy changes. So far 300 rounds and all in 1/2 moa. I cleaned it at 50 rounds and it took 15 more to go back to perfect. That is $40 bucks to a reloader and makes your target look like you should sell your gun!

 

[mkollman74]

Re: cold bore shot, how long ...

I am no expert but to me if the barrel temp and ambient temp are equal, then that is a cold bore shot. As others have alluded to, there is a difference between a cold bore shot and a clean bore shot.

 

[perkantino]

Re: cold bore shot, how long ...

Clean bore shot. Dirty bore shot. Let's reframe the debate.
It's all about carbon, and not about heat.
Someone wrote CLEAN above.

 

[Win_94]

Re: cold bore shot, how long ...

A "cold-bore shot" is a shot taken from a barrel free of fouling, whether it be metal or powder fouling.

 

[perkantino]

Re: cold bore shot, how long ...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Win_94</div><div class="ubbcode-body">A "cold-bore shot" is a shot taken from a barrel free of fouling, whether it be metal or powder fouling.</div></div>

Thank you!

It's got nothing to do with temperature. Sure heat affects POI, but that's not what a "cold-bore" shot is.

Some people fire a couple of shots after cleaning just so they can avoid a clean bore shift.

Sniper engagements are sometimes heavily spaced in theater. 1 shot now, another 30 mins later, then 1 hour later. If it were temperature, a large majority would be shooting cold bore all the time. It is rather the first shot of the day because the barrel is at that particular time clean!