Barrel temp and accuracy

D

Dave R

New member
Finally got some standard capacity (30 rnd) mags for my SAR-3 (AK variant) yesterday. Only one way to test them, right?

I noticed groups spread as the barrel got warmer. First group all holes were touching at 25 yards (max at the indoor range). Then groups spread to 1" and then 2". Point of impact seemed to move down.

Is this normal behavior for a rifle barrel, or for an AK? The one response I got at AK-47.net seemed to indicate it is.

What does your rifle do as it gets hotter?

Or could the bigger groups be due to barrel fouling? If I run a boresnake through it after 20-30 rounds, will accuracy improve even with a warm barrel?
 
Yes this is quite normal. I say its heat, not fouling.
Of course they will usually stay the same until you get into the 20s', 30s'+ then the groups will open slightly.
 
That's about what I saw. When I got to round 50-60 and the barrel was uncomfortable to touch, that's when groups started to go past toward 2".

Am I measuring groups properly? Center-to-center from the farthest rounds in the group? Or is it the radius of a circle that would cover all the holes in the group? That would generally be about half the distance from the furthest rounds.
 
Yeah, Dave, center-to-center. The actual measurement is easier if you take the outside-to-outside of the widest two holes, and subtract one bullet-diameter. Or, the inside of one of the farthest holes, to the outside of the other. It all works out the same.

One point: After you have established that your rifle will function properly at rapid fire and with a high-cap mag, I suggest not shooting in that style very often. Wear is accelerated when firing continues with a hot/very hot barrel.

For the military, in a military situation, replacement of worn items is normal and expected--and cheaper.

:), Art
 
I hear ya, Art. I don't like to spray, I like to hit what I'm aiming at.

But I do sometimes shoot 50-60 rounds in a session. Ammo's cheap, and its fun to shoot.

Is there a guideline for "safe" barrel temp? I'm assuming that, if I'm uncomfortable holding the barrel, then the barrel is uncomfortable. So I try to keep in the "warm, not hot" zone.

Any problem with that?
 
If I had to guess, I'd say that the barrel won't ever be hurt if you don't get obviously singed fingers. The average barrel can most likely take a bunch more heat than I can.

:), Art
 
223 Ultra Lite...The 1st shot does not count.

The heavier the barrel the longer it takes to heat it up. My Ruger 223 ULTRA LITE heats up on the first shot. If you count the first shot it varies from 3 1/2 inches down to 1 1/2 inces. If you ignore your "heat up" shot you have a 3/4 inch group.
 
Obvious thread digression: In a hunting rifle, only the first shot really counts. Where you have such a problem as with the Ruger ultra-lite, you have two choices: Hold low for the first shot, if the rifle is sighted in by the behavior of the next several shots. Or, sight in for that first shot, and then hold high (or whatever is appropriate for a different point of impact) for any ensuing shots.

Personally, I'd tweak with the bedding, a bit, particularly with the forearm.

FWIW, Art
 
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