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Doheny
10-02-2008, 3:55 PM
Ok, I've seen on the Mil channel and other places sniper shows where they mention a "cold bore shot." I know what a cold bore shot is, but does it have an effect on a shot's accuracy vs. a rifle that's had a few rounds already shot through it? (I realize you cannot warm up a barrel if you're a sniper...)

PistolPete75
10-02-2008, 3:59 PM
In precision rifle, a CBS is more mental than anything else.

Many people tend to miss there CBS even at short distances of 200-300yards. I see it happen all the time, even to people with custom precision rifles.

762cavalier
10-02-2008, 3:59 PM
Yes a cold bore shot can be different than if the barrel is warmed up. Knowing where the gun shoots on a cold barrel is important, especially for a sniper. As the barrel heats up point of impact can shift.

PistolPete75
10-02-2008, 4:05 PM
A sniper shooting a heavy, bull barrelled rifle that is effectively accurized with the proper equipment should not have his point of impact significantly shifting due to a hot barrel. My bull barrel will not shift it's point of impact shooting 30 rounds in 15 minutes.

Again, it's all mental. It's about getting your mind ready and correctly making your adjustments to make that first shot count.

Jicko
10-02-2008, 4:26 PM
Yes a cold bore shot can be different than if the barrel is warmed up. Knowing where the gun shoots on a cold barrel is important, especially for a sniper. As the barrel heats up point of impact can shift.

That's ONLY true for a non-trued rifle. A custom rifle, or a rifle that has been "trued" or "accurized" should NOT have this issue of POI shifting.

PistolPete75
10-02-2008, 4:30 PM
That's ONLY true for a non-trued rifle. A custom rifle, or a rifle that has been "trued" or "accurized" should NOT have this issue of POI shifting.

not completely true. non-heavy bull barrels like a sporter barrel will shift their point of impact very quickly. even after 3 to 5 rounds, they will start to shift quite radically.

the heavier the barrel, the longer it will stay consistant. but for heavy bull barrels like a m24 or amu countour, it should pretty much do it's job very consistantly without any major shift in point of impact unless your shooting in an extreme case like in 120 degree weather with like 30 repeated shots going down the barrel, especially in shorter ranges of around 500yards and less. another case is that you might be used to shooting in 100degree weather and all of a sudden it's like 20degrees and your cold bore shot must count at let's say 800yards. then you might have your normal shift of impact move a tenth or two tenth/mills max than your usual dope. another extreme case might be let's say at a 1000yards. these are very untypical situations one would cross.

these are the things i've come across by shooting my rifles and other people's rifles.

1911su16b870
10-02-2008, 4:41 PM
I am just a student of rifle marksmanship, so let me add two observations...
1. Temperature of rifle/ammo effect point of impact.
2. Bore fouling also effects point of impact.
I have heard both the above used to describe cold bore shots. I have been told the shooter should know where the cold bore/un-fouled bore first round should hit based on his data for that rifle with that load.

PistolPete75
10-02-2008, 4:43 PM
temp, altitude, velocity, etc all effect point of impact. usually most people have their dope right on well at least the elevation part. most people will mess up mentally or on wind calls.

bore fouling....depends on the rifle. mine won't matter. i can go 500 rounds and i found no shift in my point of impact nor any noticable loss of accuracy. i tend to clean my bore and rifle around every couple of hundred rounds down the tube. i don't even keep track of when i did it last. it's always an estimate.

also note, becareful of shooting on a "clean" bore. my flier of the day is usually right after i clean the barrel. becareful to not over oil your barrel which may significantly change your point of impact. i use a very little oil if i'm not going to shoot it within a few days. if i'm about to shoot it the same day or the next day, i won't oil it.

go talk to a benchrester, and they'll clean like after every shot.

for more info on precision shooting, just go down to the area of CPRC section of calguns. it's tons of fun and always challenging.