Alot of it too is the change in air density.
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Alot of it too is the change in air density.
Badger and Claven are right on with their thinking. When the temp drops the "air" becomes thinners(less dense ). If it was a perfect world, the bullet should climb and move to the right of the sight plane. But several things have happened. One is the barrels steel has shrunk in diameter very slightly. This should increase chamber pressure and make the bullet move faster and shoot flatter. However, the barrel "nodes"( a diving board type flexing as the bullet passes down the bore) are very diffrent when very cold. This too will prevent the bullet travel matching the sight. The gun powder and primer are also cold and the pressure curve will be less, this will increase "bore time" as the bullet moves down the barrel. How well you have a follow through with your shot will effect bullet placement on target. What is the light on the sights like? Is it gray and dull? Bight and sunny? What was the lighting condition when the rifle was sighted in? Was the rifle at sea level when Zeroed?10,000 feet? 60% humidity? As stated in another post, the barrel will foul much faster when the barrel is cold. As the bullet travels in the very cold air, the friction will be slightly less than normal on the moving bullet and the bullet will take longer to stabilize in flight. Then there is the wood stock on the Milsurp rifle. What is it doing to the action bedding? What delays in lock time are the frozen lubracants causing. What happens as the rifle starts to warm up? How are you mounting the rifle? Big bulky coat or parka? Gloves?
I spent half my life trying to hit a foxhole at 14,500 yards. We had a very large,fast computer to aid us in compensating for all of these factors plus 24 more factors.
We as rifle shooters have to " Kentucky Windage" our cold weather shots onto the target. The one-minute of angle tip is a very good starting point. You members who have M-91 and other Mosin Nagants rifles should have rifles MADE to shoot in the winters you have in Canada. What are you seeing in real life when shooting these rifles in the sub-zero cold? I'd like very much to know with a range report from one or more of you guys up north.
well, for me.. the two worst times to shoot are:
1. In the winter when it is snowing and blowing from the south west (in your face at the EOHC); or
2. In Late May to Early July when the mosquitos are eating you...
Either factor more has effect on the bullet path than anything else.
In all honestly, when your shooting a milsurp gun, (snipers excluded), isn't the condition of the gun, ammo and our own age more of a factor than the cold...
Other than it gets too cold for you OLD fellas to come out...LOL
@ rapidrob: I think your assumtion on cold air density is wrong. Cold air has much more air molecules than warm air. The density is higher. Thats why pilots like to fly in cold air and airbreathing turbines loose power considerably in hot air.
Cold dry air is more dense, but you also have to take humidity into acount. Hot wet air is denser than cold dry air. So location and relative humidity also come into play :)
As for shooting Mosins in the cold, 60 year old milsurp ammo becomes the limiting factor, not the rifle.
We also have lots of anecdotal experience shooting Enfield No.4 rifles in the very cold. In fact they perform so much better than most other stuff out there in sub-zero temperatures that we still equip northern Ranger batallions in the arctic with the Lee Enfield!
I think that the issue of the Lee Enfield as the Ranger's current rifle has more to do with economics than anything else. We are still re-supplying the system with surplus Enfields from the UK (back around 99) and from India (in the last year or two). I suspect these rifles are being provided at a much cheaper cost than any new manufactured rifle could be.Quote:
Originally Posted by Claven2
Wasn't it India who would issue lessor single shot rifles to some of the impressed troops who couldn't be trusted? Not that I would ever question the loyalties of the Rangers, but I believe there are political reasons also why the Rangers were not issued the FN C1A1s when they were surplus to the needs of the current force.
Mind you, I was on an ex with the Rangers about 10 years back and the tremendous shot that one of our Ranger guides made onto a Caribou on a full run at 400 yds was impressive. This despite the overall horrible condition (rust/cracked forestock) that his mid 50s LongBranch Enfield was in.
Cannonball your right in the facts about the cold air, but the dryness of the air is the big factor. I did not make that clear in the post. A bullet passing through wet air will loose more velocity faster than cold dry air. Warn dry air ,such as what we get out here in the desert causes a "boiling" of the ground air that really causes havoc at long range. In some instantses, the bullet will loft and strike the target higher than normal.
Still looking for any reports on Mosin Nagant rifles/ carbines you are shooting in the sub-zero cold.
You'll be hardpressed to get any sub zero reports from the Southern Ontario guys this year. I believe they are in for a non-white Christmas.Quote:
Originally Posted by Rapidrob
We had a milsurp shoot here in Shilo Manitoba recently, (-30C) but I was too busy and too cold to recall the performance of the MNs (if there were any MNs) at the firing line.
The Nagants sold for $45 here in Manitoba until just a few years ago, so they are commonly encountered here.
Yes, I'm afraid the days of the $45 Mosin are long gone here in Canada. They start at about $150 for a serviceable one now.
FWIW, I've shot lots of mosins in freezing temperatures and they shot consistently, but I've not done a detailed comparisson between cold and hot weather performance.
Perhaps I'll take out my PU sniper when the weather gets truely cold and shoot for groups with handloads, then try to repeat it in the sumemr with the same loads. Will be a few months before I can fully oblige though ;)
You guys must be lucky to shoot at distances beyond 300m. Thats maximum here on military rifle ranges. When its getting cold I stuck my ammo into my pocket to keep it warm. I am a fairly experienced shooter but not good enough to take all possible imponderabilities into account. The discussion is very interesting but purely academic. On military ranges we are limited to FMJ ammo only, so accuracy handloads are stopped by the non-avalability of match FMJ bullets.