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Saw mention of the rare Ruger trapgun having a straight rifled barrel to prevent wad rotation. Hastings, of course, makes such barrels too.<br>
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Do wads really rotate in barrels enough to cause degraded patterns?<br>
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If so, is this a cost effective solution? Do the results justify the expense<br>
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Are there other solutions?<br>
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What, exactly, causes wad rotation? Is it a function of the wad? Or is it a function of the barrel? If the barrel is perfectly round and mirror polished, there should be nothing to impart a spin on the wad. I can see how honing marks could cause it, but that would not be a mirror polish. Further, I've seen slugs strip right through a rifled choke tube and not turn. It's hard to believe imperfections not visible to the naked eye would have any influence on a wad.
 

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All of my Ljutic guns had shallow rifling near the end of the barrel to make sure the wad did rotate. Al Ljutic claimed that this improved patterns. I do know that the guns produced a nice pattern.

Pat Ireland
 

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It is my understanding that the wads do rotate in a barrel. Spiral and straight rifling in barrels is used to strip the wad, by slowing it down, away from the shot charge so it does not distort the pattern. Usually makes the pattern shoot tighter per amount of constriction.
 
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Brian,

Mike (PerazziBigBore) used the Hastings straight rifled barrels when he built his Ti Cole. He'd be the best person to talk to about this.

Those Ruger trap guns patterned very well by the quality of breaks that I witnessed.

ec90t
 

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Is it true that in a smooth bore barrel the wad and shot rotate clockwise in the northern hemisphere and counter clockwise in the southern hemisphere? HMB
 

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Briley makes a diffusion choke that has .005 constriction with rifling.
I have patterned these against a standard skeet choke and the pattern was about 50% larger at 15yds.
 

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With this kind of pressure behind the wads base, I can't see how a wad would spin or even why. Something would have to help the wad to begin the spinning process and there nothing in a smooth barrel to do that.

<a href="http://s142.photobucket.com/albums/r104/HapMecTweaks/?action=view&current=shotgun-shot-seq-1g.jpg" target="_blank">
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This isn't meant to say straight rifled barrels won't shoot as well as smooth barrels do either, or barrels with rings cut into the end. How could slightly cut rings in the end of the barrel grab the wad above with that kind of pressure behind the base? I think straight rifling and other such "improvements" in shotgun barrels are nothing more than sales gimmicks. IMHO Hap
 

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Mike, I think you mis-understood my post above? I said;

"This isn't meant to say straight rifled barrels won't shoot as well as smooth barrels do either, or barrels with rings cut into the end."

As for a wad base hanging up and cock-eyed over the powder charge can be heard at most clubs. Very off sounding pops at best? I think barrel harmonics do play a big part in a good patterning shotgun barrel. The smoother and more concentric the internal barrel diameter the better, for shooting almost any load/wad combo decent. My P barrel performed much better with all loads once I polished it to a mirror finish inside.

Do you think the rifled barrel has less friction on the entire charge making that a plus? I would think that instead of preventing a wad from rotating may be key for the Hastings barrels shooting good. I would imagine that could be tested over a chrono for verification too.

Hap
 

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Did I miss the explanation of what makes it spin? What ever it is, it has to be a stronger force than the friction of wad against the barrel which will, of course, resists twisting. Where does this force to start a twist come from and how big is it, generally speaking?

And how can we test the theory?

That last is easy.

Neil
 
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Neil,

I'd tend to think that one would have to study the thermal dynamics of the powder, and wad in question.

For there not to be any deflectionary forces inside the shell the powder would have to be absolutely level and the primer would have to spark dead center in the powder charge. The powder charge would also have to be the same density through out the charge.

The leg strength, on a dual leg wad, would also have to be nearly identical to keep the side loading to a minumum.

The last two parts of this equasion would be the shot charge being evenly distributed in the shot cup, and the crimps would have to be uniformly folded as to achieve equal resistance to the initial propulsion.

I don't know if there would be any aerodynamic forces acting upon the finger of the wad while it's traveling down the barrel. Being a tube, I would think that it would be very minimal. Once it leaves the end of the barrel, that's another story.

There are a lot of variables to consider and I couldn't even begin to work the math out for such a theory. I do believe that wad rotation does exist, but to what degree, I don't know.

I'm going to try a wad-lock barrel on my 1100 sporting to see if I can tell a difference. I generally shoot a 1290 1 oz load in sporting and would like to see if the pattern is a bit more uniformly distributed than a standard smooth bore barrel.

As far as testing this theory, I would think that one would have to have a clear tube and a high-speed camera to get a proper assesment.
 

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Pat, The circular rings in the end of a Monogun barrel are said to be a fluke as Al was cutting the choke and the tool broke making the "rifling" in the choke. He pattern tested that barrel with his Mono Wads (waxed Celotex, which I still have some)and the pattern improved.I notice no improvements in my scores with clean "rifling" or dirty "rifling". Must be something wandering around somewhere causing this.
 
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