I am trying to find info on the military shotgun trial that were held in the mid or late 90's. What companies entered and with what shotgun and what specifications did they have to meet? What were the test criteria, how many rounds with what type / how many malfunctions? I have searched here and google and can't find an unbiased version of what happened. Has there been one since the 90's?

I have the PDF  "MILITARY SPECIFICATION SHOTGUN, 12 GAGE, RIOT–TYPE MIL-S-3443G (AR)
04 October 1993"

You have my interest. Do you have a link or can you e mail it to me?

You can download it at this link. i'm not sure if this is the latest version. There is nothing earth shattering in it. Remington never competed. Some say becuse they couldn't compete with the price so didn't bother, others say because of their non-ambi safety. There is no doubt in my mind an 870P is a solid performer. So is the 590A1.  I like them both and own both.

Shotgun Spec

that is the same one I have.

The Marines adopted the M1014  Joint Service Combat Shotgun based on 1999 testing

Keep in mind that the "trials" were not a head-to-head competition to determine what was the BEST shotgun.
The trials were a minimum pass-fail test.
The government published a set of minimum requirements a shotgun needed to be able to pass.
If your shotgun could pass the minimum requirements you could bid on the contract.  The lowest bidder would get the contract.

I think that Mossberg was the only company to enter a gun for the test.  
Everyone else understood that that no matter how good their gun was, the bid would go to the lowest bidder who could pass the minimum test and Mossberg was the cheapest gun to make.
Since there was no way Remington was going to be able to offer a lower bid on a forged and milled steel shotgun than Mossberg's cast aluminum gun, Remington didn't bother to enter the process.

All the Mossberg advertising about "Only Mossberg passed the grueling test", was rather deceptive advertising since they were the only company to enter a gun.

And even this "mil-spec" is getting ridiculous. A lot of non-mil-spec AR15 parts are surpassing mil-spec performance.

And none of this "mil spec" business is Mossberg's or Remington's fault. The 590 A1 and 870P are excellent shotguns.

Yes.

A lot of things have changed since 1999.   Mostly due to unprecedented civilian investment in firearms