# bullet drop with warm gun?



## Splicer (Jan 14, 2004)

i put a new scope on my H&R 223 with a bull barrel and went out to put some round down range with it. i was shooting 3 shots then go check out the target.with in no time i was on the paper 2in high at 100yrds. but when i shot more then 2 shots the bullet would drop 2in into the bull.let the gun sit for 5 mins in the cold temps and it would be back on. is that from the heavy b warming up? aint 2 shots in the middle of winter a little soon? i know when iam coyote hunting i want to be on with the gun cold just wondering if this is normal? thanks


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## Rugergundog (May 21, 2008)

Most top end barrels that are properly stress relieved will shoot very well with a hot barrel. iF they do not, its is generally because of many possible problems:

1. Stress in the barrel steel
2. Barrel contact with stock as it heats up and expands making shots walk.
3. Bullet/load/barrel combo is on the ragged edge for the bullet used and the added barrel heat is causing the bullet to suffer in flight, generally because of jacket core separation.

The main issue with a barrel getting hot is really not a concern of accuracy if the rifle is assembled properly and a good barrel is used with an appropriate bullet. The real problem with shooting in a hot barrel is throat life. 

Keep this in mind, shots 1-3 will do X amount of erosion to a throat, shot 4 will generally do as much as the first three shots. Shot 5 will double that, shot 6 will double that. 

Now I am talking about VERY small amounts of throat erosion but once the barrel heats up, throat erosion accelerates dramatically with follow up shots. Now this is certainly dependent to some degree on the intensity of the chambering. A 308 Win will have much less effect on bore temps then say a 7mm RUM.

So to be honest, I would not recommend shooting in a hot barrel if at all possible to avoid whether the barrel shoots well or not, either way, it accelerates the damage to the throat when doing so.


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## Petronius (Oct 13, 2010)

Rugergundog said:


> Most top end barrels that are properly stress relieved will shoot very well with a hot barrel. iF they do not, its is generally because of many possible problems:
> 
> 1. Stress in the barrel steel
> 2. Barrel contact with stock as it heats up and expands making shots walk.
> ...


Can you write this so it is a little more understandable?


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## hunt-n-fool (Oct 10, 2006)

the barrel gets hot, expands, then the impact of the bullet moves due to the expanding barrel pressing against the stock.

To fix that, one way is to free float the barrel so that the barrel does not touch the stock.


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## M1Garand (Apr 12, 2006)

It's not the barrel heating up doing this. Something else is causing it, have you tried different brands of ammo to see if they're doing the same thing?


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## Rugergundog (May 21, 2008)

Temperature affects shooting in several different ways:

a) It affects the trajectory of the bullet.

b) It affects the temperature of the barrel.

c) It affects the ammunition we use.

d) It affects the performance of the shooter.


Trajectory Considerations

Physics tells us that warm air is thinner or less dense than cool air. As a result, a bullet encounters less resistance and expends less energy as it travels from the firing line to the target on a warm day than it does on a cooler day.

Loads generally performs better as the temperature rises. For every 20 degree change in temperature there is statistical data showing a measured decline in performance and energy dispersment. 

Barrel Temperature is a second effect that results from warm or cool outside air temperature.

On a relatively cool day (50 degrees), the outside air is able to absorb more heat from the barrel at a faster rate than it does when the air temperature is 80 or 90 degrees. This helps to keep the barrel cooler with fewer harmful side effects like &#8220;baking&#8221; the fouling in the barrel which in turn can result in a significant loss of accuracy.

Even on a moderate day (60 degrees) the barrel can become too hot to hold during the course of firing the 20 to 25 rounds that your relay may require, including sightingr shots.

Ammunition Temperature

Heat &#8212; especially excess heat &#8212; can play havoc with your ammunition. Handloaded BPC ammunition that has not been properly stored or protected from outside sources of heat or direct sunlight can suffer significant performance deterioration. Not only will the explosion of the black powder in the case produce different results, but the lube on the bullet may melt from the excess heat and flow under the bullet or into the powder column itself.

Even if you have taken the proper steps to keep your ammunition cool prior to coming to the firing line for your relay, setting you ammo in the direct sunlight or chambering it in a hot rifle for any length of time can result in an errant flyer.


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## Splicer (Jan 14, 2004)

thanks guys. it does the same with diff ammo but i havnt shot handloads or high dollar stuff. iam hunting with the gun so i dont really care so much cause i dont plan on shooting more then 1or2 times anyways. can i make it free floating? its a single shot break open style gun? at most my shots will be 200yrds anyways.so i think that 1.5 -2.0 high at 125yrds i should be good.my only thought was that when its less then 20 out 2 shots seem soon to heat up. the last scope i tuned in was in summer and it did the same thing. thanks for all the info


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## Asphalt Dave (Jan 31, 2003)

I wouldn't think that two shots from a .223, in 30 degree temps. with a heavy barrel, would cause enough heat that the 3rd shot would be 2" low.
If it does, something is really wrong. I can shoot 12 - 15 rounds through mine, in 80 degree temps, without the POI changing.


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## Jim..47 (May 5, 2009)

When you get done cleaning your gun try firing a fouling shot. Then the next day try a 3 host group watching where each shot goes. This may fix your problem which would mean no problem at all.

You can't overheat a heavy barrel in winter with just 3 shots.

Also, the ammo you are buying may be to light of loads. Light loads will always give a verticle group.


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## dogjaw (Nov 8, 2000)

Asphalt Dave said:


> I wouldn't think that two shots from a .223, in 30 degree temps. with a heavy barrel, would cause enough heat that the 3rd shot would be 2" low.
> If it does, something is really wrong. I can shoot 12 - 15 rounds through mine, in 80 degree temps, without the POI changing.


I would tend to agree. I do know someone who *had* a Weatherby lightweight .270 that would not group without waiting 5 minutes between *each *shot, but with a heavy barrel. I have a question, is the total group in a vertical string, or 2 separate groups where the bullets are side by side? Check this site out and see if this is your problem.
http://www.6mmbr.com/verticaltips.html


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## roger23 (Jan 14, 2001)

you need to try hand loading,,weigh each bullet,I have found not all bullets from the box weigh the same and can vary quite a bit,,also make sure you have a good powder scale,,it is a pain but if you want repeatability each round needs to be the same


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## M1Garand (Apr 12, 2006)

Rugergundog said:


> Temperature affects shooting in several different ways:
> 
> a) It affects the trajectory of the bullet.
> 
> ...


While this may be true, we are still talking a factory rifle's groups at 100 yards. Not a high end bench gun and long range groups. 

We are also talking the flyer being after 2 shots so it's not a cold barrel shot or fouling issue. If I were shooting factory loads, I'd start with different makes of ammo. If I were working a load up and shot a group like this, many times it's a seating depth issue and seating deeper in 1/4" increments on the seating die can bring this in. 

What I'd start with is clean the barrel very well, including a good copper cleaner. Shoot a fouler, then if you're using factory ammo, use a brand with a bullet known for good accuracy. Federal makes a Gold Medal Match ammo with the Sierra Match King that should shoot as good as any factory out there. Unfortunately it's about $30 or so a box but if it doesn't shoot well, I'd think you have to look at it's the rifle and not capable in it's current state or the shooter.


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## dogjaw (Nov 8, 2000)

Re-read his post. The odd part is that after waiting 5 minutes, he hits dead on again for several more rounds. It would help to see what the group looks like.


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## M1Garand (Apr 12, 2006)

A barrel shooting 2 shots shouldn't drop the third like that due to barrel heat, ESP in a heavy barrel. I agree it's odd, but something else is going on besides barrel heat causing this.


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