Advantage To X2’s?


Dear Technoid,

I want to ask you about the differences between factory made choke tubes and Briley X2 choke tubes. Is there any practical difference in performance between Invector tubes and the ones made by Briley or other after market manufacturer?

Thanks a lot,
Mak

Dear Mak,

I have a number of Brily X2 extended chokes that I use in my Beretta 303 gas gun right alongside the Beretta factory flush chokes which came with the gun. I can find no difference in the patterns between the two if the constrictions are the same. It seems to me that the main difference is the extended portion of the X2 chokes. They add a slight bit of muzzle weight and enable the shooter to change chokes by hand, rather than with a wrench, if he is so inclined. Personally, I always use a Royal wrench on my chokes, extended or flush. I find it faster than doing it by hand and I like the security of being able to snug a choke in and remove it easily. Another slight advantage of the extended choke compared to the flush choke is that the extended chokes have the choke designation clearly stamped on the collar where it is easy to read and you don’t have to count those invisible little notches in the rim of a flush choke.

Briley (flush or X2 extended) do have one big advantage over the stock flush Beretta Mobilchokes. If you deal directly with the factory, Briley will sell you a choke cut to a specific dimension. If you know exactly what you want, this is a great deal. If not, then it doesn’t matter.

I don’t currently own any guns with the Invector Plus chokes, so I can’t comment on those. When I owned guns with the older standard short Invectors, the same comments applied as to the Beretta.

You have to be very careful with the new Brownings and their choke markings. The Japanese Browning screw chokes have always had the reputation of using less constriction in their chokes than other makers. Both the old standard Invectors and the new Invector Plus chokes do this. With the old Invectors it really was a cause for complaint as the guns usually patterned more open than the choke designation indicated. You often had to go up one choke to get the proper performance.

The new Invector Plus chokes used in overbore (.743″ or so) bbls have muddied the water. In my experience the Browning overbore barrels do not respond to the same dimensional restrictions the way that standard bore barrels do. The Browning overbore barrels seem to shoot tighter with less constriction when dealing with the more open chokes, but require normal constriction when going up to the tighter chokes. The overbore Ruger I tested with virtually the same barrel I.D. did not exhibit this tendency. It’s a strange world.

Predicting pattern percentages based solely on choke constriction was always an iffy thing. With overbore barrels, it has become just that much harder. I hate to keep saying this, but there is absolutely no substitute for pattern testing.

As to the other choke makers, the products vary. Some of the more expensive choke makers offer claim careful machining and concentricity. You will need some sophisticated concentricity gauges to verify this. Others offer varying formulae of choke forcing cone length to parallel. Others use a full taper choke with minimum parallel. All that I am aware of work within the limitation having all their screw chokes of the same length.

Here’s what I mean by that: Let’s say that a give screw choke series is 3″ long. That means that the skeet choke tube is 3″ and the Full choke tube is also 3″. The skeet choke will simply have less constriction. In the world of solid chokes, that skeet choke with .005″ constriction would be about two inches or less long. The solid full choke of .35″ constriction might be six inches long because the greater constriction requires a more gradual forcing cone and longer parallel to stabilize the shot. Screw chokes of equal length can’t offer this. That’s one of the reason that most handicap trap shooters and virtually all pigeon shooters who want the best full choke at any cost stick with solid chokes.

In theory extended chokes would offer a slight advantage in the tighter constriction because they are longer and can offer more gradual tapers and longer parallels. Frankly, I don’ t think that the very slight increase in length between extended and standard chokes is enough to matter in this area.

One area where custom screw chokes could be a major advantage is in the area of skirt jump or gap. The rear of all screw chokes (the area called the “skirt”) is greater in diameter than the bore. Obviously, this is to keep the skirt below the bore line so that the shot charge doesn’t blow the choke out. Sometimes these gaps are quite large. Mass produced choke makers have to anticipate the largest possible bore variance from the gun maker and their own smallest possible choke skirt variance. It’s called a “ganging of tolerances”. The bottom line is that most mass produced chokes have an extra margin of safety built into the skirt diameter just to make sure it doesn’t stick into the bore and cause problems.

Unfortunately, this extra deep gap provides an extra jump for the shotload. The deeper the skirt, the greater the shock to the shotload as it passes over. A custom choke maker can tailor the choke to your barrel and minimize the gap. Teague in England is the very best at doing this. You can barely see where the choke skirt ends and the barrel ID begins. He does amazing work. None of the American custom chokes I have seen even come close.

Bottom line: to get the most out of custom chokes, you will have to know what you want in terms of constriction and resultant patterns and also be able to accurately measure your bore with a bore mike or send your barrels to the choke maker. Anything else is just guessing. There it is in the real world.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)

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One Response to Advantage To X2’s?

  1. Steve Jacobs says:

    Great answer. Thanks for knowledge and the ability to communicate it.

    Like

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