Briley Diffusion Chokes


Dear Bruce,

After years of competitive pistol shooting, I took up shotgun shooting almost exactly one year ago. I started shooting Sporting Clays, & joined an excellent group here in GA – the Social Shooting Club. Have been following your column after being referred by a fellow competitor almost since I began shooting.

I have always been a “gimmick” type- looking for anything that may give an edge. I have printed out all your load/choke info, & have the “Choke Chooser.” In our last two shoots, I have shot with several of our best shooters, & they all seem to use the Briley Diffusion choke exclusively. They all say they simply vary the shot size, based on target distance, & they work on all presentations, from “in your face”, out to 50+yd. I called Briley, but was not able to get any info, other than “they work & most top shooters use them.”

Do you have any experience with them (Briley’s Diffusion Choke?). If so, what’s your opinion?

Thanks for your input,
Larry

Dear Larry,

I met some of your fellow Social Shooting Club members at last year’s SHOT show. They were nice guys and it would be a privilege to shoot with them. I was very interested to hear what they had to say about Briley’s “Diffusion” choke.

As to the Diffusion chokes, yes, Briley sent me a bunch to test. I have them for one of my 30″ FN sporters and for my Beretta gas guns. Their performance puzzled me. Obviously, they are built to impart some spin to the wad and hopefully to the shot charge. This “should” widen the pattern by centrifugal force. I tested them with skeet shells at 15 yards and found that they did pull some of the center pellets to the fringe each when compared to a true cylinder bore, but that the difference was so slight that it wasn’t mathematically significant.

Here are the numbers I got:

BRILEY DIFFUSION VS TRUE CYL BORE
BERETTA 303 @ 15 YARDS
FEDERAL 1-1/8 OZ #9 nominal count: 658

30″circ 27″circ 20″ circ 20-27 27-30 ring
Diffusion 620 572 420 152 48
Diffusion 609 577 418 159 32
Diffusion 608 554 419 135 54
Cylinder bore 617 574 432 142 43
Cylinder bore 626 591 444 147 35
Cylinder bore 620 589 443 146 31

AVG diffusion 612 568 419 149 45
AVG cyl bore 621 585 440 145 36
% difference 1.42% 2.99% 4.93% -2.47% -18.66%

BUT, when I shot them at skeet I definitely felt that I was getting better breaks than I got with my cylinder bore. I felt that the fringes of the Diffusion patterns were stronger than those of the cylinder bore. No, I can’t prove it with a two dimension pattern paper, but there it is. This is purely a subjective impression over an objective observance.

Now as to your Georgia pals using them for 50+ yard presentations, well I just dunno about that. I know you Southern shooters are good, but that seems to be really stretching that choke. Briley bills the Diffusion choke as the “spreader that really works”. After all, it is supposed to be even more open than cylinder bore. To me, anything over 40 yards is strictly Full choke territory, not spreader territory. Yes, on a bet I have shot very long crossers with open chokes and you can do it, but it isn’t optimal. The “Force” may be with you, but the law of averages isn’t. Maybe your guys know something I don’t. It wouldn’t be the first time, that’s for sure.

I don’t really have any hard facts why the Diffusion gives me more reassuring breaks at skeet, even though it doesn’t show up on the pattern paper. If I were pinned down, I’d say that you would have to start looking at shot string. It is just possible that the Diffusion choke retards the wad and/or does something with the shot charge to effectively alter the shotstring.

But the shotstring theory has problems too. At short skeet distances, with the full 1-1/8 oz loads of #9s that I use, long shotstring is actually an advantage. This is true because you have a large number of pellets and can sacrifice some to the string without compromising pattern density. At longer distances with larger pellets, the a long shotstring robs the pattern of much needed density and performance suffers. If your Social Shooting friends have good luck with the Diffusion chokes at both long and short distances, that sort of takes the shot string theory out of it.

Bottom line: once again the all-seeing, all-knowning Technoid has come up short. You can be sure of one thing though. Next time I shoot FITASC, I’ll stick those Diffusion chokes in and try them for a complete round, long and short shots included. If there is something to these chokes that I have overlooked, I want to know about it.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC

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