My friends, Kathy

I went back and re-googled the research I had referenced. I had had a mental short curcuit and associated the vibration research with the Lost River folk that make the Chey Tac bullets. The harmonics study was done by Three Rivers Technologies. Here's a link

http://www.vni.com/successes/threerivers.php

Apologies for the confusion.
 
I went back and re-googled the research I had referenced. I had had a mental short curcuit and associated the vibration research with the Lost River folk that make the Chey Tac bullets. The harmonics study was done by Three Rivers Technologies. Here's a link

http://www.vni.com/successes/threerivers.php

Apologies for the confusion.

Thanks Vibe,
this was an interesting article -- though I sure couldn't follow all the math.

I found their conclusion paragraph interesting, "...The most significant realization should be small, tight bullet groups across a range of loads and temperatures (which affects internal ballistics), with no adjustments required on the part of the shooter. "

Best,
Michael
 
Great info

Thanks Vibe,

I didn't understand any of the math involved but the explanation and theory should be read by all and give everyone a lot better understanding of barrels and tuners.

It also helps us understand why as we are tuning a tuner that the point of impact can and should change.

It would make me think that you are looking for a course tuner settings that are either going to be high or low impact point then tune from there.

It also confirms at least one of Bills Theorys that once the right setting is found.....it is found and should not have to be touched.

BUT the muzzle does not literally stop.

Charlie
 
Bill's method of finding this setting needs a bit of tweaking, I think. Getting the same POI at 44m (I think that's what he said he was shooting at, no?) from two bullets travelling at speeds differing by 40 ft/s seems counter-productive. If they were both fired perfectly they would have different POIs *because* they differed in speed by 40 ft/s. If they're both getting the same POI from the current setting, this says to me that you're still getting too much muzzle movement, and you're not done tweaking yet. Perhaps this method might give a useful starting point. But in theory it wouldn't give you an end point. Once tuned you should get two distinct groups from both speeds, not one group. But both groups should be as good as they'll get, without changing tuning settings for different speeds.

One of the things that stood out to me about this article is they used two masses in their description, two tuners. Confirming the benefit of the mid-barrel mass/tuner, if not the necessity. Haven't poured over the math portions yet, looking forward to reading it all later. Thanks for posting this one! Bookmarked.
 
It Works

Shorty, If you don't think Bills way of tuning works. You can try it easy and cheap. Get a roll of lead solder and cut it to 1oz. 2oz. to a pound if you want. Just weigh the pieces. Make a nice tight wrap on the end of your tuner or weight. Then put a couple wraps of tape to make a tight fit. You can put any amount of weight on the tuner you want.
 
Effect of differences in bullet speed

Shorty,

I agree that shooting bullets of different speeds will result in different POI; however, I don't think that negate the Calfee method of determining how much weight to put on the tuner. I don't have any ballistic software so don't know how much vertical spread you can expect when shooting bullets that differ by 40 fps. I'm guessing it's not much. In fact, maybe the bullets would still form one ragged hole when all or virtually all vertical spread is caused by the difference in speed of the bullets.

I'm reminded of when I was testing different brands and lots using a chronometer. Sometimes the best groups were shot with bullets showing a large standard deviation, while some poor groups were shot with bullets showing a small standard deviation. It just might be that the variance in speed, doesn't have as much impact on accuracy as we thing it does.
 
what actually causes the barrel to vibrate

is it the firing pin hitting the cartridge
or the explosion in the cartridge
or the passing of the bullet through the barrel
or is it something else i'm missing here?
 
It's not that I don't think it would work. I'm just thinking that perhaps after following his routine there might still be some minute adjustment left to do, that's all. Perhaps you're both right and the amount left after that is so small as to get lost in the noise.
 
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