Would you trick it out from the start?
Use the Beretta Chokes? Adjust the shims???
End cap weight????

OR Just shoot it as is for awhile???

Thanks

Shoot it for a bit and see what you need/want to increase your shooting enjoyment.

You need to adjust the shims so it fits you.
I found I needed to add mag cap weight for MY liking

I would shoot it for a while. I did the same thing last summer bought one before I shot it sent it off to Briley had it all tricked out and now I'm shooting a Browning 725 and the a400 is for sale and I know ill never get my money back.

How much for your A400?

I have it listed in the classifieds marked down to $1800. I have $2400 in it with all the Briley stuff done to it.

Funny-I may do the opposite. If I shoot the A400 well, I will sell the 725

"Tricked out": I would get the end-cap and two weights as well as the oversized bolt release and that's it. None of those require the gun to be sent off. The gun is light, the weights made the greatest difference in swing ability. The small factory button bolt release will get old very fast, get the Briley oversized well spent.
You might make a post to see if anyone has the cap and two weights for sale on this forum. I know we have an extra weight that won't get used.
The chokes work fine, shim so it fits you and then shoot the heck out of it. The only other thing to do is stock work if it doesn't fit. You do need to shoot it for 4-6 months prior to looking at that. Ideally if you ordered with an adjustable comb would be of benefit. Well spent money and Gun fit is everything in this sport, you have to be at one with our gun to maximize your success and enjoyment.

TY

And since it comes with those shims, you can make all sorts of minor tweaks with cast and drop to get it close if not spot on. That sure helped me decide on getting one because I am LH, and most guns come with RH cast or you pay a lot more for the LH stock.

Shim it to fit you and take it out and enjoy. The Beretta chokes are fine. Order a Briley bolt closure button. Order a weighted mag cap if you feel you need it after some shooting. The only other thing I would suggest especially if you alternate with an O&U is to send the trigger assembly to Coles for a trigger job. You can install the bolt closure button yourself, thanks to guidance on YouTube. The last trigger assembly I sent to Coles cost around $110. It was money well spent.

As stated above all the above help,the A400.
The paddle release and oversized bolt make the ergonomics/ mechanical aspect of shoot mulch easier. Have done the whole 'shmear'

Gun fit is paramount. The shims work well being left handed they were a life & $$'saver
Enjoy