cold barrel/warm barrel clean/dirty

C

checkmyswag

New member
What affects the difference of impact between the first shot on a rifle and the follow up shots.

Is it the barrel being cold or the barrel being clean on that first shot that causes the follow up shots to impact slightly differently?
 
A "cold bore shot" impacts slightly diffrent as does one from a squeeky clean bore. This is why target shooters always fire a fouling shot before they shoot for group size. Acurracy usually doesnt drop off from being dirty unless the barrell is new or it had a lot of rounds fired.
 
The effects of multiple shots (in rapid enough succession to heat up the barrel) varies with every barrrel, with one of the major factors being the barrel length, and thickness.

Target shooters prefer a "bull" or "varmint" contour- the "heavy barrel" moniker if you will. The greater mass of steel takes longer to heat up- and harmonics are also affected less by the heat, maintaining same POI even with a hot barrel. Shorter barrels also generate less "whip" and have an advantage from that perspective. Generally speaking, I would go with a barrel as short as necessary to deliver the desired muzzle velocity (which usually doesn't make as much difference as many think) and as heavy a contour as comfortable for the intended use.

Hunters OTOH need to be able to hit POA on the first shot- and prefer lighter barrels for obvious reasons.

As mentioned, clean/dirty and hot/cold have varying effects on barrels, and every one is different. Some guys clean both powder and copper fouling after every shoot, some only when accuracy degrades, and most- somewhere in between...
 
My son's 243 will not hit the paper on the first shot at 60yds. All other shots group neatly around 1" at 100. Temp doesn't matter to this one, but it sure does hate a clean barrel. Each rifle is a little different of course. My 270 doesn't noticeably care if it's hot, cold, clean, or dirty out to 200.
 
Not set rules. Some guns shoot the same cold bore or after a few rounds. Target rifles (used in High Power and such) don't seem to care, hot or cold. Same with the Bolt gun I used in LE.

Some do make a difference.
 
My match mule (M1A supermatch) shoots about 1 MoA high with a clean bore. I don't bother really correcting for it as we shoot offhand first in the match.
 
I wonder

how much difference it makes when you have shot several rounds, heating up barrel and the ACTION, ....

Then chamber a new round, leave it in the hot chamber for a minute or more (heating up the powder inside the round), then firing.:confused:

This could happen in a hunting situation where you fire several shots at a fleeing animal, then chamber the next round before setting off on the trail, then finding the animal several minutes later, and taking a final shot.

Has anyone ever duplicated this sequence at the range? I would be curious to learn the results.

Just thinking out loud, here.:rolleyes:
 
Checkmyswag:

When I was shooting on several Marine Corps rifle teams I shot both the M1 and the M14 and I held a NRA master classification. When I shot rapid fire my barrels heated burning to the touch and my shots were always where I called them. As for clean barrels, at times I ran a bonze bore brush followed by one dry patch during the match; at times, I didn't follow this procedure. I found no difference in my scores. Maybe with bench rest shooters hot and cold and clean or fouled make a difference.

Semper FI.

Gunnery sergeant
Clifford L. Hughes
USMC Retired
 
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I zero with a cold clean bore with 3 shots. I clean the gun and go to the field with it because I know what my zero is when it's clean and cold.
 
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