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Old December 28, 2022, 12:50 AM   #1
Mike38
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Lower point of impact cold ambient temp.

I experienced something I've never noticed before today. Hopefully some of you experts out there can help me with an answer. I have a Ruger Single Six in .22LR that I do not shoot often, maybe two range trips 100 rounds total per year. It was my Father's so it's a gun I plan to one day give to my Grandson. Anyhow, the last time I shot it the ambient temp of the range was probably around 70 degrees F. Today, the temp outdoors was single digits (ammo was in back of my truck for hours so it was cold) and the temp at the indoor range was probably less than 40 as the Furnas was not working. The point of impact was about 5 inches low at 15 yards, it was dead on a few months ago. Would the cold temp of the revolver cause this low point of impact, or the cold ammo? Maybe combination of both? Ammo was SK Pistol Match if that makes a difference. Thanks.
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Old December 28, 2022, 04:03 AM   #2
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I would say it was the cold ammo.

Burning gunpowder is a chemical reaction, and like most, is, to a degree, temperature sensitive.

while a lot of work has been done, and is still being done to come up with powders that are not affected by temperature changes, we're not there, yet, though we are generally better off than we were in the past.

However, extreme temperatures, like single digits or very high temps do have an effect. Cold slows down (most) chemical reactions, and heat speeds them up. Very cold powder produces less pressure than normal, resulting in lower velocity and lower bullet impact on the target.

Extreme cold will also have an effect on the gun, and on lubricants as well, oils get thick, metal becomes brittle. But these affect the operation of the mechanism more than anything else. Particularly semi and full autos.

Low point of impact was because the ammo was very cold. next time, put it in your pocket for those hours instead of in the back of a truck in the cold and I bet you see about normal expected performance.

Same applies in the opposite direction with heat. Saw a revolver that got blown up by ammo that was too "hot". High summer in the desert, triple digit air temp, ammo left for hours on the dash of a truck, direct sunlight, windshield glass "magnifier". Pressure was beyond safe. Very rare, but it can happen.
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Old December 28, 2022, 07:13 AM   #3
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5" at 15 yd may be too much for the temperature difference. Was the bore cleaned before that range trip? You probably shot more than one shot. Did the point of impact remain low for all the subsequent shots?

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Old December 28, 2022, 09:19 AM   #4
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Quote:
5" at 15 yd may be too much for the temperature difference.
Yup, a very general rule of thumb is to subtract about 2fps from the muzzle velocity for every degree F the temperature drops. But lowering the muzzle velocity in a revolver typically raises the point of impact on the target due to longer dwell time--it doesn't cause it to drop.

The muzzle velocity change from temperature could be as much as 130fps, but I wouldn't expect that to make anywhere near 5" of difference at 15 yards, and if it did make a difference, it should have made the point of impact higher on the target.
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Old December 28, 2022, 10:57 AM   #5
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All of the testing and data I've seen on cold temps is with center fire rifle ammo. With that in mind around 2 fps loss for each one degree is about right with MOST powder. Some powder however is much less sensitive and will only see around 1/2 fps loss per 1 degree. But I've not seen any testing with 22 rimfires in cold temps. I just don't know how much cold effects that ammo.

Also, normally you get muzzle flip in a handgun and the bullet that stays in the barrel longer will impact higher because the muzzle is higher when the bullet exits. But does a 22 recoil enough to have the same effect?

Another theory. Just a guess really. But most 22 ammo has grease in the grooves of the bullet. In extreme cold that grease is going to be a lot harder, and it could have an effect on bullet impact.

It seems to me that the cold temps are causing this. Exactly how may still be a mystery. Wait until temps warm up and get back to the range with the same ammo and report back.
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Old December 28, 2022, 02:29 PM   #6
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I got to thinking about the different possible variables, there are some not given in the OP.

Aside from the temperature difference what are the other differences between this time, and the last time you shot that gun??

First question, is it the same ammo you used last time??

Does your Ruger have adjustable sights?? The Ruger Single Six does not have adjustable sights. The Ruger calls the gun with adjustable sights the Super Single Six. People frequently just say "Single Six" referring to either version, but when trying to (remotely) troubleshoot a problem, it makes a difference.

Along with cold ammo another likely factor is a cold shooter. The OP says the indoor range was less than 40F. Wearing gloves??? My fingers get cold and stiff easier today than they did back when I was a younger man, and cold stiff fingers simply don't have the same sensitive feel. It's not impossible the shooter was pulling his shots without realizing it.

Another question, indoor range...were you outside the last time you shot that gun? Lighting can make a difference.

Quote:
But most 22 ammo has grease in the grooves of the bullet.
I think you are confusing .22 rimfire bullets with centerfire lead bullets. The .22 uses a heel type bullet, there are no grease grooves, and regular .22 ammo has used a wax coating, not grease, for about a century.

5" at 15 yds is extreme, more than usually seen, but since it happened, its clearly not impossible.

Cold gun, VERY cold ammo, cold range, cold hands, perhaps poor lighting, perhaps all those together were the cause.

How's the trigger pull on your Ruger?? Light triggers and cold numbed fingers (or wearing gloves) affecting your feel of the trigger often results in a change of impact/poor groups.

Repeat the test with everything at comfortable room temperature, changing nothing else if/when possible. If your results are different, then it was the cold. If not, then its something else. Sorry I can't be more helpful.
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Old December 28, 2022, 02:52 PM   #7
buck460XVR
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Quote:
Originally Posted by tangolima View Post
5" at 15 yd may be too much for the temperature difference.
My thoughts also, especially for such a short distance.

The previous poster mentioned gloves, that was one of my first thoughts.
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Old December 28, 2022, 04:51 PM   #8
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No gloves, same ammo. On the left side, the revolver says "Ruger .22 cal. New Model Single-Six. Maybe New Model Single Six and Super Single Six both have adjustable rear sight? I did notice that the grease on the bullets was so cold it was more like wax than grease, so that and cold powder could very well be the reason of the low point of impact. All that, and the dummy pressing the trigger could be the problem. Warming up the barrel by shooting it didn't change point of impact, so I adjusted the rear sight. Anyhow, it's something I've never noticed before, because it's rare that I shoot in such cold conditions.
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Old January 6, 2023, 02:49 PM   #9
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Temperature affects ammo but I wouldn't expect to see 5 inches at 15 yards or at any pistol distance really. I know it's a consideration for long range shooters but never heard of it being an issue for pistols.
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Old January 6, 2023, 11:25 PM   #10
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I really doubt that this POI change is due to cold ammunition.

I'll bet you a beer that if you take the gun to an indoor range that it shoots exactly the same and that the sights have been changed inadvertently.

The rear sight for a single six has an elevation screw with a small spring underneath it. I can't imagine that spring breaking ... but... my gun has engraved on the side ".32 H&R Magnum New Model Single Six". I call it a "single six".

I do remember when I was a kid taking my clock radio apart and tightening all the screws inside. My dad later explained that those were variable capacitors and.. there was no chance that clock radio would ever work again. Maybe someone helped you by tightening that screw?

I live in Wisconsin. 20 degrees isn't cold, it's just about time to think about putting on a sweater. Ammo works fine down to about -20 F at which point it's too cold to reload and you enjoy the indoor range. The powder doesn't much care about the cold when it's 20 degrees.
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Old January 8, 2023, 01:16 PM   #11
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Under 40 degrees my finger start to get cold pretty quickly when shooting. And I'm not too sensitive to cold temps, I can be out shoveling without a coat at 0 degrees. The problem with shooting in the cold is that you are just standing around, not moving, with your hands extended as far out as possible. I'm pretty sure the cold effects me more than the gun or the ammo.
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