I have owned twenty nine Beretta 92 variants over the past 30 years... I have owned a Wilson Brig before. It is a nice gun, but wasn't my favorite. (I later sold it)
Realize it is still all done at the Beretta factory. They just add some Wilson parts. Wilson has admitted that they don't even open the boxes, once they are delivered to their location from Beretta... Not unless you order the trigger job from them. So, it's still a factory Beretta gun, just specced by Wilson.
Wilson originally specced the tighter frame to slide fit too. But after Beretta did that for Wilson, they tightened up their fit on all the other Beretta 92 variants. So, it doesn't matter what 92 you buy now - they all are tighter in that regard.
I personally like the M9A3 better than the Wilson Brig. And to this day, the M9A3 is my favorite 92 variant.
A long time ago, on another forum, someone was asking about whether they should buy a Wilson Brig vs another model. I remembered typing out a comparison about why I liked the M9A3 more... I went looking, and I found it. I had written it back in 2016.
Anyway, I thought I would past it here, as it may help you:
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Why I preferred the M9A3 over the Wilson Brig Tactical pistol:
1. I like the sight picture of a standard type 92 slide the most, which the M9A3 also has. The squareness of the front sight area on the Brigadier slides makes the front sight not as quick to pick up. The base where the front sight sits at is squared off on the Brig slide. It doesn't have that curve on it like a normal 92 does around the front sight area...
Also, the front sight IS a little bit shorter on the Brig slide (compared to the M9A3 slide). If you put the slides next to each other, you can see that. Taller sights always pick up faster for me.
I think it is much easier to see the front sight on a standard 92FS slide, with the curved area under the front sight... (this is 1 thing I like about a 1911 - the top of the slide is curved, and it makes it so quick to pick up the front sight). On this M9A3, the Vertec style slide (dovetailed front sight) still has the curve of a regular 92FS. I like this much more.
2. Also, the front sight (facing the shooter) on the M9A3 has about a 45 degree cut to it. The Wilson front sight has a 90 degree cut (shadows effect seeing that white paint more). The white circle around the tritium on the M9A3 pops out more - because of the 45 degree angle facing the shooter. It picks up more light since it's at a 45 degree angle.
3. I REALLY like the different angle of the safety levers on the M9A3. By raising the levers upwards a bit, it does cause less issues when tying to clear a jam (if need be). I've messed around with this, and the levers do what is intended by that slight change. But, you can always get the decock only version too, or install the conversion kit yourself.
4. The grip of the M9A3 feels better to me. Generally, I prefer standard serrations over the checkering Beretta uses. But, with the rear strap being covered by that Hogue conversion grip on the M9A3 - I don't mind the front strap checkering.
When I hold both guns (either with a loaded mag in each or no mag in each), I prefer the feel of the M9A3 in my hand more than I do the Wilson. Granted, I do NOW have Hogue grip panels instead of the VZ grips on the Wilson (I like them better than the stock VZ's)... But, the M9A3 feels much better to me in the hand.
5. The rear sight of the M9A3 is just perfect. I didn't think I'd like the lack of white circles on the rear tritium. But the silver rings work great around the rear tritium on the M9A3. The eyes still gets drawn to the white around the front dot - but you still have 2 rear dots on the rear sight.
I'd never use the Wilson, with the all black rear sight, as a home defense gun - as you have absolutely no way to see the rear sight in low/no light. Granted, I have solved that problem by having Trijicon replace that rear Wilson sight with a normal tritium rear. But, as I am talking about the Brig Tactical and how it comes FROM the factory with the all black rear... The M9A3 wins this IMHO. It's too bad the Wilson sight doesn't come with a single tritium rear dot - like Straight 8 sights.
Also, I wish the rear Wilson sight had a square cut instead of a curved cut (in the sight channel). I just don't like rear sights with a curved sight channel. Again, this was solved by me having Trijicon replace that rear sight on the Brig Tactical.
6. I shoot the M9A3 a little better than I do the Wilson with the factory sights - especially at 15 yards. Again, I think this may be because of that rear Wilson sight on the Wilson gun - with the curve in the sight picture.
Now, do I like the Wilson? Yes. But if I was offered a choice of just 1 of them... Between the 2.... I'd choose the M9A3, hands down... No real hard decision for me...