Muzzle device setting sensitivity.

Bill Calfee

Gun Fool
Muzzle device settings sensitivity.

CYA friends:



This is a thread I started on the "members only" side of CYA.

With so many folks having trouble finding a MD setting these days, I thought I'd move this thread to the "public" side of CYA too.



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Muzzle device settings sensitivity:


When I first developed the muzzle device, I felt the setting was super critical.


As a matter of fact, I went to great extremes to make sure I knew exactly where the MD was mounted on the barrel.....


My first MD's were adjusted by moving them for and aft on the muzzle of the barrel.


I even made up a crude, adjustable depth gauge that I could set when I had the muzzle stopped, then use to re-set the depth if I had to remove the MD for some reason, so as to get it back to the exact thousandth.


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After Ron Hoehn came out with his easily adjustable MD, and I started using them, I always used one of my Hoehn slave MD's to do my initial testing of a new build.

I figured if a new barrel wouldn't shoot, why waste a new MD fitting it up front......so I used my slaves.....still do.


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Anyway, one day I fit one of my slave MD's to a new build and tested it......( I'm going to kill two birds with one stone here)


I stopped the muzzle on this new build with a setting where the number 15 wound up on the reference line on the MD body...... 115, 140, 165, 190 etc......I don't remember exactly.


So I bored and fit the new MD, and set it at the same setting as my slave.......


And the new builds muzzle was still stopped; it shot exactly the same with the new MD as with my slave.


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So one day, I forget why, I checked the calibration of both the new MD and my slave.....


(The calibration is where the weight head sits in relation to the back of the MD body, which will vary on some HH/MD's.)


And I found that there were several thousandths difference in the calibration of the two MD's....


Plus, there were a few thousandths difference in the depth of the counter bore, for the barrel, between the two MD's.


These two differences, totaled together, amounted to 20 some odd thousandths....


In other words, the weight head of one sat about 25 thousandths either further past the muzzle, or closer to it, than the other......I don't remember which.


Yet, with about 25 thousandths difference in weight head location, and both MD's set at the same setting on their dials, the build shot exactly the same.



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So from that point on, which includes the same situation repeating over and over again, I changed my mind about how critical MD settings have to be.



And since that first learning experience had the MD set at some reading that ended with the number 15 on the dial, I've always used the 15....which means full turn adjustments when I set an unknown MD/barrel combination, ie., other than the standard .900 x 24's that are so popular, which the MD can be set for one of them without ever firing the gun, 90% of the time.

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So the number 15 has no scientific or rational basis.....it simply means that .025" of adjustment is about the minimum that has any affect on the way a MD functions.

If you have your MD set to "truly" stop your muzzle, .025", or one full turn on the HH/MD either way, won't have much affect on your accuracy.

If you don't have the muzzle "truly" stopped, oh yes, .025" can have a major affect.

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An aside: On rare occasion I'll have a situation where I can't seem to stop the muzzle with a 15 setting, but, it is so rare so as to be almost non-existent.


Your friend, Bill Calfee
 
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