How long to wait between shots for a true "cold bore" shot?

[Whiterabbit]

So, long story short, I am going to characterize rifle performance for cold bore shot to see if I can affect the cold bore performance.

The goal of course is to reduce or eliminate the cold bore first shot effect in performance.

Now, to do that, I need to shoot a cold bore shot, followed by a group or two to see what's going on. That's the easy part. Then repeat a bunch of times. That's the hard part.

The hard part, is when can I shoot another cold bore shot? How long does it take for the rifle to cool, after, say, 10 rounds, back to a cold bore?

One day? One hour? 20 minutes? 6 hours? two days?

If it's one day, I can get one data point per range trip, and it's going to take months to gather data. If I can shoot a group once an hour, I might be able to get a good population of data in a long weekend.

I honestly have no idea at what wait time I should expect the rifle to be "reset" back to an "I need a fouling shot or barrel warmer or check my zero" shot state. So I thought I would ask those that compete, or otherwise play the long range game.

Ideally, this is for cold bore shots that change POI rather than velocity, but I'll take what I can get, if you have experience with only one or the other.

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It's really easy to say "it'll take a day. wait one day between strings." My question is, what's the shortest time I can wait and still have valid data? Less than a day? How much less?

[9mmrevolver]

Why not get a temp gun. Temp your gun before the first shot and then wait till it drops after you’ve fired your groups

[Whiterabbit]

Sure, thought about that. Temp where? does the whole barrel inside and out have to be ambient? Then the question is, how dry? becuase ambient takes forever. I can force it there via dry ice, but condensation will put moisture in the barrel.

I'm not convinced I can data my way out of a cold bore shot.

[waveslayer]

Well this can be tricky... several options here...

1. Shoot it at whatever the ambient temp is. Wait and Shoot it once it reaches the same temp.

2. Clean cold bore, is the barrel just been cleaned etc.. and is shot at ambient temps? Then clean it and Shoot it again..

3. Place a fan down the action with the barrel pointed up and cool it at the range, I do this on hot days.

4. Place the rifle in a ice chest and freeze it to get a cold bore shot at realistic winter conditions, you'll be surprised by the results if you have poor quality stuff and scope...

5. Do what I do. I take a bucket of water, ice chest with use, funnel that has a clear tube that matches my barrel size. I then take a cup and poor cold water down the barrel, pointing the muzzle down , and the barrel will cool in about 3 seconds. Run a few patches to remove all the water and go to town. I've been doing that for years and it works by far the best. Even room temp water. Cleans the gun too. I'm not a fan of removing fouling at all, but this method cools your barrel asap!

6. Be patient

7. Always set your rifle with the muzzle straight up, it will cool much faster with the action open

My wife thinks I only have 3 guns

[bsumoba]

get a barrelcool

[Whiterabbit]

I understand the nuances in that statement, but how long to use before I can be a cold bore again?

The question is one of time!

[focus]

There are at least 4 conditions that will affect the first shot.

1) Clean bore - Barrel condition changing until fouled.
2) Cold bore - Barrel temperature is same as ambient. Barrel temp changes until its heat soaked for a given shot cadence.
3) Cold shooter - Shooter condition changing until "groove" is entered.
4) unknown environmentals - Firing solution changing until DOPE is proven.

I still haven't resolved my cold shooter issues.

Cheers,

[sigstroker]

Make a heater for your barrel. Ever watch a Formula One race? The tires in the pits have heating blankets on them. When a car comes in for new tires the driver doesn't have to take it easy until his tires heat up, they are hot as soon as they're put on the car. Formula One is the zenith of car racing technology. They heat the engine and transaxle oil, coolant, etc before they even start the thing in the garage. The tolerances are so tight that the pistons are seized in the cylinders when the engine is cold.

[freonr22]

I would never use a laser thermometer. Use, instead a k type thermocouple. Taped to the barrel, with foam I sulation, for your question. Infrared thermometers are not accurate o. Shiny surfaceces. And are also suceptible to previous ambient temps

[Whiterabbit]

Anyway, there is lots of focus on temp, but nowhere have I really established that temp is the only factor. It's not my intention to study the factors that affect cold bore shot vs subsequent shooting.

I just want to characterize the effect of loading practices on that first shot, whatever factors are involved. To do this, I don't need to measure them. in fact, that's undesirable.

I just need to be sure the shot I am taking is what we call our "cold bore" shot. No cleaning, no artificiality, no collecting random temps when we have no idea if they represent what a cold bore shot actually is.

I just need confidence when the rifle is in the cold bore condition.

waiting a day for this is a known-good condition, but will take a LONG time to gether data.

Meanwhile, competition shooters probably have experience with zero shift after waiting a long enough time between strings within the same day. And so probably can give me good guidance if a shorter period of time will result in giving me that cold bore shot.

That was the purpose of posting in this forum.



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Maybe I should ask in this way:

If you are a competition shooter, and you just shoot one stage, one string, etc, and are waiting for the next stage to start, or the next target, or the next opportunity for your competition, at what point do you know you've had to wait too long between strings are and going to be affected by the rifle "cooling down" too much and need another "fouler" to get the rifle back into condition again?

A day? Less?

[jimmykan]

One of my rifles throws a cold bore shot about 0.3 - 0.4 mils in the 11 o'clock direction. It will do this whenever the barrel has been allowed to cool (un-shot) for about 30 minutes.

Another rifle will only throw a cold bore shot on the first shot of the day, and does not seem to do it again until the next range trip.

So, hard to say what's a reasonable cool down time to observe another cold bore shot in your rifles. You'll just have to try once every 24 hours, then every 10 hours (or once when the range opens and again when the range closes), then every 9 hours, then every 8 hours and so on

[ar15barrels]

So, long story short, I am going to characterize rifle performance for cold bore shot to see if I can affect the cold bore performance.

The goal of course is to reduce or eliminate the cold bore first shot effect in performance.

Now, to do that, I need to shoot a cold bore shot, followed by a group or two to see what's going on. That's the easy part. Then repeat a bunch of times. That's the hard part.

The hard part, is when can I shoot another cold bore shot? How long does it take for the rifle to cool, after, say, 10 rounds, back to a cold bore?

One day? One hour? 20 minutes? 6 hours? two days?

If it's one day, I can get one data point per range trip, and it's going to take months to gather data. If I can shoot a group once an hour, I might be able to get a good population of data in a long weekend.

I honestly have no idea at what wait time I should expect the rifle to be "reset" back to an "I need a fouling shot or barrel warmer or check my zero" shot state. So I thought I would ask those that compete, or otherwise play the long range game.

Ideally, this is for cold bore shots that change POI rather than velocity, but I'll take what I can get, if you have experience with only one or the other.

------------------------

It's really easy to say "it'll take a day. wait one day between strings." My question is, what's the shortest time I can wait and still have valid data? Less than a day? How much less?

I think it takes a week or two to get a truly "cold" bore.
I have some theories on this because I do not see a change after just 24 hours.
I think some of the "shot goes high" factor we are seeing from cold/dirty bores is from oxidization of the copper fouling and maybe from the hygroscopic nature of powder fouling.
This is a more time (and storage conditions too) sensitive issue than simple barrel temperature.

I always make a point of checking zeros the day before any match where I travel.
I do this on the way to the match the day before and I do not run into high first shots.

Another experiment I wanted to try was to store the gun overnight with a heating element in the barrel that would keep the barrel 20-30f warmer than nominal.
This should theoretically reduce the fouling oxidization from humidity as the humidity should be lower with the elevated temperature.
I have a roll of nichrome wire here somewhere to wind a heating element around a fiberglass rod and then slide a fiberglass sleeve over the element, but I never got around to doing the experiment...